Planning Sites and Buildings in Warm Climates v. 3.0

May 2016 Build Simple Inc.

www.BuildSimple.org

Above: Haitians building a dormitory of alternative materials, 2012

This information was first developed in 2008 as in-house training materials for Wycliffe Associates Construction Services, Orlando, FL, USA. Thanks to all the WA staff and volunteers for their labor of love in training novices how to deal with other places and cultures.

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Contents Chapter 1 Looking for Land 3

Regional Information- Warning Signs- Boundary Information- Site Photographs- Land Slope- Clean Water- Human Waste- Stormwater-

Chapter 2 Preliminary Soil Evaluation 14 Soils for Footings- Soils for Sanitation- Soils for Walls- Field Soil Tests-

Chapter 3 Watch Out for Problem Soils 25 Low Bearing Strength- Landslides- Dry Soil Problems- Humid Soil Problems

Chapter 4 Shaping Buildings for Hot Climates 34 Planning for Comfort- Ventilation- Shading- Insulation- Plantings

Chapter 5 Building Across Cultures 39 Communication- Form Follows Function?- Hidden Costs

Chapter 6 Choosing Building Materials 48 Lightweight Materials- Bamboo- Wood- Natural Fibers- Roofs and Insulation- Heavy Masonry- Humidity Control- Thermal Mass- Earthbag- Brick- CEB- Mud Block- Rammed Earth/ Cob- CMU Infill vs. Confined Masonry

Appendix Regional Hazard Maps 62 Seismic Hazard Information- Land Resource Stress- Carbonate Geology

Bibliography 68

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Chapter 1: Looking for Land

All land is not equal. You are looking for inexpensive land that is close to utilities and transportation. It must be big enough for the buildings you need. How do you choose between different building lots?

Steep or soggy land can increase building costs dramatically, or may not fit safe wells with septics. Land with high water levels during part of the year may make wastewater difficult to handle. Large proportions of the wrong kinds of clay in a soil (common in damp areas) or landfill may require expensive foundations. Other land may settle if groundwater levels are lowered by wells, or under the weight of buildings.

Get as much local advice as you can. This booklet has been developed for those who have difficulty finding local advisors in subtropical and tropical regions. It was first developed by the Wycliffe Associates Construction Services Department to help local program directors to decide about purchasing property for new buildings. Aid workers for many other organizations have similar needs. We hope this resource will make planning less costly and more productive by giving non-engineers some tips about what to look for.

Some of this information could be collected by a local volunteer. Science or social studies teachers or volunteers with a construction or technical background can help.

REGIONAL INFORMATION Regional maps like those in the appendix will help us to check for earthquake risk levels, the presence of limestone geology, and some other limiting factors for development.

Get local opinions on these hazard levels for your project site. Information may be available from local builders, city building departments, and regional universities or research centers. Important topics you must be aware of:

What problems with water and power supply are common?

What kind of rocks and bedrock are in the area?

Are there any caves or mines in the area?

Have there been any landslides, mudslides, or areas of collapsing soil in the region?

What kind of damage happens to buildings, roads, or bridges in the area?

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SITE WARNING SIGNS: Think very carefully and get a lot of information before you buy land with any of these characteristics:

· Large wet areas · Very soft or sandy soil in earthquake-prone regions · Very sticky clay soil · Dry, cracked soil areas, gullies, bare gravel or soil · A general hummocky appearance · Surface water that disappears underground · Leaning trees or posts on slopes

BOUNDARY INFORMATION If you are purchasing land from a future neighbor, they can show you the limits of the property. There should be some obvious locators like fences, walls, ditches, or rows of trees. If not, ask them to stack some rocks or place some stakes near the corners. People will need to visit the site several times to evaluate it, and everyone must be looking at the same piece of property. A legal survey will have measurements and compass directions.

Before paying for a survey you can find out the approximate lot size and shape. Use multiple roles of colored string if you have to. Mark each distance with a permanent marker and a strong loop of tape next to it.

Rectangles need angle measurement, which is hard to do. To be accurate without expensive equipment, break a lot up into triangle shapes. Mark their corners and draw a small sketch. Measure all 3 sides of each triangle, and a designer can sketch out the size of the lot.

Make sure you clearly show if your piece of string is the A-B property line or the A-D interior measurement. Then measure the string later with shorter tape measures.

SITE PHOTOGRAPHS Digital photographs of the land can remind you where trees and buildings in the distance are.

Left: Panorama photograph of land in Cameroon

Use a camera that takes panoramas automatically, or take separate pictures

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carefully, each photo overlapping the previous photo so that it is clear how they connect. Two separate series from each boundary line, one looking in and one looking out is very helpful. Take careful notes in a notebook so you can label them later (like: 'northwest boundary, looking outward, garden at the left’, etc.). Additional closer photos should show any existing structures, landforms (cliffs, ditches), special plants, surface water, as well as the kind of buildings in the neighborhood.

Above: Looking uphill in Cameroon If plants block the view of the site, try a ladder or climbing a tree to get better views before you remove all the plants to take photos.

ABOUT SLOPE Land that is too flat may be soggy in damp climates. Land that is too steep will require expensive retaining walls or higher building foundation walls. Remember, buildings are flat, and they need flat space around them.

You don’t need to know the exact 3-D shape of the land before purchasing it. But you need to know about how steep it is. The amount of slope is called the grade or gradient.

Use a 1 m long level stick and a tape measure to measure the grade. Hold the level so one end touches the ground and the tool is centered. Aim it straight down the hill. Measure how high the other end is above the ground.

Slope (also called grade) = Vertical change Horizontal distance

Land that slopes 1 cm in 1m (100 cm) of distance has a 1% grade. 1 cm/ 100 cm =1% This is very flat and may be hard to drain. Stormwater will puddle.

3-5% grade lets water run off, but is easy to develop. It is not too steep for roads even if you have freezing weather sometimes.

Land that slopes 10 cm in 1m (100 cm) of distance has a 10% grade. 10 cm/ 100 cm = 10% Some retaining walls will be needed to fit larger buildings or sports fields on these hillsides.

Land that slopes 20 cm in 1m (100 cm) of distance has a 20% grade. 20 cm/ 100 cm = 20% This is steep enough that it will increase building costs and may make it hard to fit buildings on. If you have freezing weather sometimes, roads should not go straight up.

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If you are using non-metric tools, then use this list for a 4’ long level: Half inch= 1% 1.5 inch= 3% 2.5 inches= 5% 5 inches= 10% 9.5 inches= 20%

Above right: Site walls around a building on a hillside Right: Water should run away from your building

Make sure that rain runs around and away from building walls. Rain always flows downhill, so on the uphill side a building needs a small swale or channel that will direct the water away. It is a good rule to have the land slope down away from the building on all sides. On the uphill side it might only slope down 10 cm in 3 m (4” in 10’). If you can, in humid climates locate the swale at least 3- 6 m (10- 20’) from the building.

SIMPLE SLOPE MEASUREMENTS Land with a uniform slope (when you look up or down or across the slope, the surface of the land is mostly straight lines, without dips or curves):

Measure the difference in elevation or height of at least 3 different locations. It is best if these can be the corners, but for a preliminary site evaluation, 3 typical spots will do, as long as we know the distances between them. A contractor can mark these with stakes or stones and take these 'spot elevations' with a helper using some water and a hose.

Land with curves or bumps may be harder to understand.

If it has a steeper part and a less steep part: The slope of the steeper part is important to know if it is a major part of the site. Measure the height of 3 different spots in the steep part. Also measure 3 different heights of the rest of it.

If the land curves: Surveyors usually locate and take spot elevations at a couple of high points on each ridge and a couple of low spots in each valley. For a preliminary evaluation some good photos with some rough estimates of height or depth may be enough.

Flat land with little slope:

Can you see where water flows, especially onto or off of the property? Look for leaves or debris missing where water flows, or lined up at the edge of a very slight channel. In some climates slight depressions will have darker leaves and soil. This is the lowest path where the water runs.

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CLEAN WATER Harvesting rainwater is one way to provide clean drinking water. You will need a cistern large enough to store water from the rainy season through the entire dry season. And you will large enough roofs or hard surfaced areas to collect enough water.

A well seems much simpler. But think about how the people in your area find and use water. Will your neighbors all expect you to share your water with them? Will they want to bring cattle to drink at your well? Wells in dry agricultural regions often cause environmental problems because farmers intensify their land use. In many places new wells for aid have caused serious land overuse and soil erosion. Talk this issue over with local people that you respect.

If you choose a well, make it a safe and healthy one. Wells are easily contaminated by pit toilets or septic systems that are too close. There may be no regulations at your location to prevent a neighbor from building one of these right next to your property line. Plan to have enough room so your well will be far enough from all property boundaries. 30 meters is a good separation distance for level ground.

How much land do you need to have a well and septic or septics? That depends on the shape and slope of your land, and on what your neighbors have.

If your neighbors don’t have any wells near their property boundary, you will need at least 0.4 hectare (1 acre) and must save the center of your site for your well.

Water deep underground or seeping through the upper soil usually runs from higher areas towards lower areas. If your land is higher than your neighbors, good for you. Their sewage water will flow away from your land.

Right: Minimum size to fit well and septics on flat land

If your neighbors have wells nearby, you will need more land. Keep your septic system or pit toilets far enough from their existing or future wells. If your soil is very sandy, more distance may be needed.

Locate a well further from neighbors who are uphill.

On sloping land you need at least 0.7 hectare/ 1.7 acres. Probably since your land will be a less than perfect shape, you will need more than this. This is why you want a survey or sketch of how big your land is. It is easierout how wells and roads fit in when you can draw them.

Right: Minimum lot size on sloping land

60 meters is a safer distance to separate a well from pit toilets or septic systems that are uphill. This means that if your land slopes down in one direction, your well should

HUMAN WASTE Remember, for any waste system to be successful it must be accepted by local people. They have to feelworth the effort to keep it working well. Discuss preferences and ask for suggestions before introducing something new. Always offer a real choice, so

In many parts of the developing world pit toilets are or wider. If the platform is old, there is real danger of it collapsing. A small child may feel more vulnerable to falling in. In many parts of the world small children refuse to use pit toilets a

Some civil engineers think that soakaways (deep infiltration tanks) agroundwater because they bring the septic liquids too deep underground. It may be safer to keep them onmeter or less below the surface. But how?

0.7 hectare/ 1.7 acres. Probably since your land will be a less than perfect shape,

This is why you want a survey or sketch of how big your land is. It is easier to find out how wells and roads fit in when you can draw them.

Right: Minimum lot size on sloping land

60 meters is a safer distance to separate a well from pit toilets or septic systems that are uphill. This means that if

rection, your well should be

located 60 m from the uphill side and 30 m from the downhill and all level sides.

Left: Large lot needed to protect a well in a low spot

If your land is the lowest in the area, you will need a very large lot. A long valley will need more distance between well and septics on some sides. If the center of your land is a low spot, you need almost 2 hectares/ 5

Remember, for any waste system to be successful it must be accepted by local people. They have to feel. Discuss preferences and ask for suggestions before introducing

w. Always offer a real choice, so people will feel more ownership of changes.

In many parts of the developing world pit toilets are standard. Pits are often 2.4 m/8’ deep and 1.5 m/. If the platform is old, there is real danger of it collapsing. A small child may feel more vulnerable to

In many parts of the world small children refuse to use pit toilets and contribute to polluting their area.

that soakaways (deep infiltration tanks) and long drop toilets (pit toilets) pollute groundwater because they bring the septic liquids too deep underground. It may be safer to keep them on

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located 60 m from the uphill side and 30 m from the

: Large lot needed to protect a well in a low spot

n the area, you will need a very ll need more distance between

f the center of your land 5 acres.

Remember, for any waste system to be successful it must be accepted by local people. They have to feel it is . Discuss preferences and ask for suggestions before introducing

1.5 m/5’ or wide . If the platform is old, there is real danger of it collapsing. A small child may feel more vulnerable to

nd contribute to polluting their area.

long drop toilets (pit toilets) pollute groundwater because they bring the septic liquids too deep underground. It may be safer to keep them only a

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A septic leachfield is a more complicated system, using a sealed tank (that sometimes needs pumping) and a series of perforated pipes that distribute the liquid just under the ground.

Western style flush toilets use too much water for many areas. Simpler slab or squat or ‘Turkish’ toilets can be manufactured porcelain or made by local craftsmen with tile. They can be flushed with a bucket, using less water.

Right: ‘Turkish’ toilet

A squat toilet can stay much cleaner than a western seat toilet if the users are accustomed to them. Many people used to Turkish toilets will squat on top of a western type toilet seat, dirtying or breaking it. The squatting position is also healthier and keeps legs strong.

Simpler alternatives don’t need septic systems. In the developing world, simpler is usually best.

The simplest way to handle human waste on a small scale is the ‘fill and cover’ arbor-loo.1 This shallow pit- 1 m deep and 1 m wide is the right size for one or two families.

Left: The arborloo process Below: PeePoo bags

A cast concrete platform is slightly larger than a Turkish toilet. A supply of leaves or straw or sawdust or ash sits by the hole. Each person adds enough to cover the waste. When the pit is full, then dig a new one. A single mother can accomplish this herself. She then plants a vine or tree in the old pit. The family has less disease and the plant grows better from the fertilizer.

Composting waste systems don’t need water either. Some concrete block pits are built with two openings. Every 6 months one is closed up and the other is opened. The waste is not removed until it has been left alone long enough to become safe to handle. Some of the most effective divert urine so the solid waste is not too wet. A squat toilet top is shaped to catch urine and lead it away, or a toilet seat has a

1 Sustainable Sanitation and Water Management, The Arborloo

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special diverter added to it. This has been accepted in Asia and the urine (germ-free among healthy people) used for fertilizer.

If you are working with slum tenants or refugees, some places don’t have enough room for any toilet. It may be possible to fund a system of sanitary waste bags. PeePoo bags are biodegradable and have a liner with enough ammonia to neutralize germs in human waste.2 They can be picked up within 24 hours (before beginning to smell) and placed in a sealed barrel.

After only a month the PeePoo barrel can be opened and used to grow plants. An organizer must collect and compost the waste, but in one Kenyan slum women earn a living selling the bags for 3 cents each. They refund 1 cent when returned for composting.

For best heath, near toilets without running water, add a tippy tap.3 This simple handwashing station is made out of a used plastic container and some string for a foot control. Germs aren’t passed on when feet work the ‘tap’.

Right: A Tippy tap made out of an old bottle or tin

Handwashing (scrubbing well) with either soap or ash can reduce deaths from diarrheal diseases by almost half.

GRAYWATER Much waste water from a household can be re-used. Bathroom sinks, tubs, showers, and laundry machines all produce slightly dirty water, called graywater. Usually this does not contain many germs. It can be run directly to feed plants. But where graywater from several houses joins up on the ground it causes erosion, and leaves sludge behind.

Left: Graywater running on the ground

If graywater is stored for a full day it can become contaminated as nutrients and bacteria multiply. Don’t store it. It is also better if graywater doesn’t run on the surface of the ground. In the developing world shower stalls are often used for washing clothes. Staff at a school may bring their laundry to wash at work. If

2 Sustainable Sanitation and Water Management, PeePoo

3 Check out www.tippytap.org

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they have small children, they will include diapers to wash. If you can, keep graywater underground. Do not let it ‘daylight’.

Right: Underground graywater outlets Below right: Testing a perforated pipe outlet

Drains from showers can run underground to a shallow leachfield- a perforated pipe set in gravel. Wrap this with landscape fabric and pour gravel or small stones around it. Then cover, and plant vines or trees or vegetables. For best health, don’t grow root vegetables like carrots or yams in this area.

Make sure that hair and other fibers don’t flow into perforated pipes. Or even cheaper and easier to clean out, run graywater to simple underground outlets made of buckets, clay flower pots, stones, bricks or blocks.

Try out your graywater system before you cover it up. The space in the pipe or buckets or under the blocks has to be big enough to hold the water until it soaks into the ground.

Kitchens either contain a lot of grease and juices from food and soap, or a lot of bleach as disinfectant. If this is true for your buildings, don’t try to water plants with sink water. Run kitchen water through a settling chamber where you can clean out grease and food scraps. Then run it underground.

STORMWATER Builders always made roads with curbs and used gutters to trap and collect stormwater. Special pipes had to direct it away from buildings. Often during heavy rains, it washed soil away and caused problems.

Newer low impact development (LID) ideas work better to prevent soil erosion even in the developing world. · Don’t collect water · Don’t speed it up · Let water soak in near where it lands · Less pavement, more porous surfaces · Plants hold the soil and clean the water

Right: Rain garden below lawns and roads, Maryland, US

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Find out how water travels on your land before you build. Help it continue to flow without disturbing buildings.

Locate hard surfaces above green parts of your land. Slope them so the water runs down to help plants. Provide good soil and start plants that your site users want. Vines or vegetables, or special herbs will get their attention if they are planted at the downhill side of the house. In dry regions, make a ditch and lead the rainwater to feed special plants. The more water that soaks into your land, the more reliable your well will be.

Right: Tropical plants catch runoff after the level pavement spreads it out

Keep plants growing on slopes so rain can soak in and soil stays in place. Strong grasses like vetiver can grow even in drainage areas. They can be planted in soil held in poly rice bags through holes in the fabric. Then the plants won’t be washed away before the roots are strong enough to resist the flowing water.

Don’t concentrate rainwater. Avoid solid, raised curbs. Don’t run gutters together, but let them pour out at many places. Where rain runs off of roofs or paved areas, make a level area that will spread the flow out.

On sloping land, you will need swales above buildings or roads. But at the end of a swale, spread the water out again.

Left: Spread water at the endof a swale Bottom left: How to build a level spreader

Use strong lawn or rough surface small rocks at the downhill side of the level area. This will slow the storm water so it soaks in.

Because roofs increase how quickly rain runs off, lead roof water to special drainage areas. Ditches that slope gently can be rain gardens, where water can soak in slowly and plants that need moisture can flourish.

Or even better, use your rainwater. Place drums or cisterns to save stormwater for use later. Keep it covered to prevent mosquito growth. Rainwater is much healthier than surface water from streams. Where

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groundwater is also polluted, saving and using rainwater carefully will improve health.

Above left: Cistern in Kenya Below left: Graywater and rainwater for a Kenyan fish pond

Where water is scarce, captured rainwater may allow more food plants or animals. The concrete tanks shown at left combine graywater used by 100 people with captured roofwater. This flows into a covered tank to settle for 2 days. It then flows through two slightly sloped beds that will grow a water-tolerant vetiver grass. As water takes 3 days to pass through the grass tank it loses nutrients and becomes cleaner. The deeper tank at the downhill side is where edible fish will be raised. They will be healthy and grow quickly in cleaner water.

There are many ways to use water. Keep in mind where water will be flowing and keep your options open.

Below: Vetiver grass planting in Kenya to stabilize a drainage channel

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Chapter 2: Preliminary Soil Evaluation in Warm Climates INTRODUCTION To choose a good building site someone must know a little bit about its soil. Soils with too much sand or clay or silt can make wastewater treatment areas and building foundations large or expensive. Good soil can be used as a building material. Water close to the surface of the soil or running onto your site from hills above can also make it a more difficult place to build.

The soil tests that follow may confirm what your contractor or local people already know about the site. They may also give you a clear indication whether you will need to ask for help from a professional.

Use these tests with the site questionnaire checklists and other information.

If you already have good footings and wastewater treatment that works ok, but want to check soil for earth building, please see the Soil Tests for Earthbag and Contained Earth series online at www.BuildSimple.org.

FIELD SOIL TESTS You may want someone to help with the digging.

Equipment you might need:

· shovel, pick-axe

· hand soil core tool or auger

· post-hole digger

· your site survey or location description

· a notebook, pens, a ruler and a contractor's tape measure

· plastic bags, masking tape or labels

Above: A hand soil auger with a shovel.

Sketch where the soil samples are dug from on a plan of your land. Call them A, B, etc.

If the weather has been dry, take some water with you. You may be able to finish most of the tests at the property. Label your samples by putting them in a marked bag. If it has been raining recently, the land is in a low-lying area, or near a lake or stream, you may need to dry some of the soil samples out to test them well.

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First check if the soil is very different in the higher or lower parts of the site. In places where you will want buildings or pavement use the auger or post-hole digger to get one or two samples of each kind of soil from at least 50 cm below the surface. In stony soil holes can be dug with a shovel. If there are small areas of different soil in a corner or along an edge of your land, don't worry about them.

These tests are to check for obvious problems with the upper layer of soils. Different soil layers below affect buildings. If you have an auger, dig deeper and find out if the soil changes below, and where the water level is. If you find standing water in any hole, measure how deep it is and note the location and date.

Scrape debris and topsoil away from each testing site. The top 40 cm (16 inches) of soil usually contains plant matter and humus. Topsoil is darker and smells musty, especially if damp. It is also a little springy when you squeeze it, and may have a slightly fibrous appearance. If you’re not sure how deep it goes, cover a handful with water in a bowl and stir. Organic material floats. Topsoil leaves dark stuff all over the top of the water.

Find out about the subsoil below it. You should be able to measure how deep the bottom of the topsoil layer is. Sometimes there is no topsoil or very little. If the soil is in a low-lying flat area (or one that used to be low) it may have very deep organic matter. If so, this soil won’t hold heavy buildings well, and may keep settling lower.

Rub some subsoil between your fingers. With all the pebbles, roots and sticks taken out, does it feel a little gritty like salt? Or does it feel smooth like flour? Sometimes a few drops of water on damp soil will make it easier to feel the sand. Clay is the smallest particle size, silt a little larger, and sand the largest and grittiest. If the soil feels even a little gritty it contains some sand.

If you are considering building with your soil, mix a couple of clumps or shovelfuls from each different area together to get an average sample. Take out any rocks, gravel, or debris. Put some of the subsoil in a labeled bag and note which part of the site it came from.

It is good if the soil is firm and requires some effort to dig. Loose soils are more expensive or dangerous places for buildings. If it can be dug by a shovel without using your feet, it is a very soft soil. When you need to use a pick to dig, the soil will probably have high bearing strength. If it is very hard to dig, but not rocky, check whether it is a lateritic soil that forms a hard layer at the surface up to several meters thick. Ask for local advice. It may make a very good support for a building, but you may need different testing methods.

Note how hard it was to dig, and the color of the soil, whether it is a light brown or reddish-brown, or if it is very dark or light gray. Notice if there are any colored or white residues in or on it.

Use Chart 1: Unusual First Observations (on the next page) if you find soft soil, topsoil deeper than 40 cm, some unusual colors, or very porous, light soil. A porous soil is unusual, but it will have 40% or more open spaces. It will feel light weight, and crush down to a smaller volume if you stamp on it or squeeze a clump.

For more ordinary soils start with the Pinch Test on page 17, then use Chart 2 or Chart 3 to evaluate your soil.

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Chart 1: Unusual First Observations

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Red:

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PINCH TEST: Take a pinch of soil. Add water until wet and mix it. Rub it between your fingers.

1. Does it feel very gritty and fall off your fingers? The top picture is sandy or light soil- go to Chart 2.

2. Some soils stick a little but more to your lower finger. When they dry they brush off clean. The 2nd picture is silt, a light soil- go to Chart 2.

3. Does it stick to your upper finger and make your hand dirty? The 3rd picture is clay or heavy soil- go to Chart 3.

4. Many soils are a mix of all three. If it is gritty but also sticks on your upper finger- go to Chart 3.

5. If your soil is not gritty, and holds together very well but is not sticky, it might be a tropical clay. Squeeze a ball of it, and use a table knife to cut a piece off. Is the cut piece shiny? Then it is clay and go to Chart 3.

Look for the photo on Chart 2 or Chart 3 (on the following pages) that looks more like your soil. Then follow that chart.

JAR TEST: If you have a very sandy soil you may want to see if it has different sizes of sand and how much clay it contains.

Take a small bottle with straight sides and fill it half full with soil. Add water to cover. Shake well and then leave it untouched for 24 hours.

When it has settled, look for different layers. You can see separate sand grains. They will be on the bottom. Are there different sizes of grains?

You can’t see silt particles unless you use a magnifying glass.

Even a magnifying glass won’t let you see clay particles. Can you tell how much is clay, silt and sand?

A ‘well-graded’ soil has some of each. It should have different sizes of sand particles also. The picture at right has a little clay and silt, but the sand is all the same size. This is in between well-graded and poorly-graded.

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Chart 2: Testing Light Soils

Green: Not likely to be a serious problem

Red: Find out more about this!

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Chart 3: Testing Heavy Soil Red: Construction may be expensive or likely to be damaged

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BALL TEST:4 Drop balls on a hard, flat surface. Take well-mixed soil just moist enough to hold together. Shape it into 4 cm diameter balls. Drop them one at a time from 1,5 m high.

1. Do your balls flatten out with few cracks? The top picture is soil with a lot of clay- it will not drain well for wastewater

2. Do balls crack, but also leave a wet mark? Use a drier mix and try again.

3. Do they split into several pieces? The 2nd picture has less clay, and will be less of a building problem. It is good for earth building.

4. Do the balls shatter? The 3rd picture shows a silty soil or a sandy clay. It may be weak for footings. Unless it contains a lot of sand, it won’t drain very well for wastewater.

RIBBON TEST:5

Knead moist soil well. Remove grit. Roll it on a flat surface or press it very carefully into a shape of uniform dimensions. Cut the roll off 4 cm long.

1. Can you hold a 6 mm diameter roll by one end? It’s a little plastic- probably safe to build on.

2. Hold up a 4 mm diameter roll. If it does not break, but a 2 mm diameter roll breaks, the soil is plastic. Check for expansive soil (see page 26).

3. If a 2 mm diameter roll does not break when held by one end, this is a very plastic soil. This soil is very likely to have expansion problems.

4 Minke, Building with Earth page 22

5 Schoeneberger et al, Field Book for Describing and Sampling Soils page 2-53

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PERC TEST: Percolation tests show if a heavy clay soil will make your wastewater disposal too expensive. Test where a truck with a water tank can be driven, or after a well is working on-site. The goal of this test is to see what the maximum continual rate is at which water can drain through the soil.

Dig a 30 x 30 cm (12” x 12”) hole 60- 75 cm (24- 30”) deep (or to the level of the bottom of soakaways if they will be used). Some small stones are placed in the bottom of the hole. It is then filled to the top with water. The hole is refilled with water so that the bottom 15 cm (6”) are under water for at least 4 hours. If the soil is a very fast draining sand or gravel, the percolation rate may not slow down. The hole should be filled several times.

The length of time it takes for the water level to drop 25 mm (1 inch) is recorded, until the water drops at the same rate twice in a row. This is considered the percolation rate of the soil. A perc rate of 30 minutes to an hour is long, and will require large wastewater treatment structures. In the US soil with perc rates of more than an hour are not used for wastewater. Perc rates that are too fast are also considered problems. A very permeable sand or gravel may drain in less than 1 minute, and cannot treat wastewater without contaminating the groundwater below.

SOIL STRENGTH Standard bearing capacities of average soils range from 2.5- 4 ksf (17- 30 psi).6 Many soils are not average. Engineering tests of soil bearing strength are expensive, so alternative ways to evaluate soil strength are helpful.

Soils of low bearing capacity cause problems and expense for construction. For one or two-story construction soils do not need to have very high bearing capacity. The soils that are most likely to require over-sized footings are poorly graded silts or sands or clays. Light and heavy soils are evaluated in different ways.

Sometimes soil footing problems result from a seasonal high water table, or weak or unstable layers buried beneath soil layers of adequate strength. Is there damage to structures in similar areas? Dig a little deeper.

24- 48 hours after a rain is a good time to test soil bearing strength. In a dry season, soils could be watered well once or twice and examined the next day. If this is not possible, write notes about how the soil looked and how long it was since the most recent rain.

6 Underwood, J.R. and M. Chiuini, Structural Desig, page 589

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STRENGTH TEST 1: Clay or silt soils Weak clays under normal footings may only start to settle after construction is finished, and 'significant settlement can continue for years...’7 Clays do not drain easily, and weight added to them can over time slowly squeeze moisture out from the soil pores, reducing the soil volume.

Weak clays or silts are often easy to dig. Clay that must be loosened with a pick may be twice as strong as clay that can be dug with a shovel.

If undisturbed and moist clay or silt soil can be penetrated by a fist or thumb, its bearing capacity is probably very low. Dig a test hole carefully- don’t loosen or compact the edges of the hole. You probably should repeat the test at several locations to be sure that this problem soil is everywhere you need to work.

This chart shows about how strong (with a safety factor of 3) many ordinary claylike soils usually are (if not compacted and without other unusual shapes).8 A stiff or hard clay or silt will probably not need oversized footings. A soft or very soft soil will.

Consistency Compressive strength

Characteristics SPT N: # blows/ 30 cm Ksf psi

Very soft <0.5 <3.5 Easily penetrated several inches by fist <2

Soft 0.5- 1 3.5- 7 Easily penetrated several inches by thumb 2- 4

Medium 1- 2 7- 14 Can be penetrated several inches by thumb with moderate effort 5- 8

Stiff 2- 4 14- 28 Readily indented by thumb but penetrated only with great effort 9- 15

Very stiff 4- 8 28- 56 Readily indented by thumbnail 16- 30

Hard >8 >56 Indented by thumbnail with difficulty >3

Note: SPT values refer to Standard Penetration Test described below.

7 Lindeburg, page 36-2

8 Gaylord, Structural Engineering Handbook, page 5-5

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STRENGTH TEST 2: Sandy soils Since sandy soils aren’t squeezed smaller with less water. If sand settles, it is more likely to settle immediately under the weight of the footing and wall. If this is slight or equal on all sides, little or no damage happens.

Sand gets weaker when wet with flooding or seasonal high water levels. With no flooding, dense sands that are coarse or well-graded are often strong. Densely packed grains and angular grains are stronger. A densely packed sand with clay or gravel probably has a good bearing capacity. Gravel and coarse sand in natural thick beds can have a safe bearing capacity of between 8 and 10 ksf (56- 70 psi).9

Sandy soil is most accurately tested on the site. If a promising site has sandy soil that seems to be fine or not very dense, do a simple approximate penetration test with a pipe and a hand-held sledge hammer. If it takes 10- 20 blows or less with a 15- 30 kg sledge hammer to drive a 50mm outside diameter pipe 30 cm into the soil (starting below the topsoil) the soil is fairly weak.

ADDITIONAL TESTS A pocket penetrometer is a tool a little bigger than a tire pressure gage that measures on an exposed layer of soil the amount of force required to move or press into the soil. This provides a reliable field estimate of soil bearing strength in soft clays and silts.

If these field tests or any surface conditions show there might be serious problems, call an engineer. They may know the area already to compare the site in the local geology, or take soil cores from deeper levels to discover where and how serious soil problems are. Often they need a backhoe to dig 2 m or more down to look for groundwater and changing soil layers. An engineer’s fee will be cheaper than a ruined building.

Contractors can make a standard penetration test (SPT) with a 65 cm (25.5”) long piece of pipe and a 63.5 kg (140 lb) slide hammer. It evaluates deeper soil layers well. The SPT is best for sandy soils. It may be less accurate results clay and gravelly soils, but can assess them if laboratory tests are not available.

The pipe must have an outside diameter of 50mm (20”) and an inside diameter of 35mm (14”). The slide hammer should fall a distance of 76 cm (30”). Drive the pipe 15 cm (6”) into the ground. Then write down the number of blows needed to drive it in each successive 15 cm (6”). The number of blows is called the 'standard penetration resistance' or N-value.10

If more accurate soil evaluations are needed when an engineer is not available, a dynamic cone tester can be made out of steel rod with a cone shaped tip according to standard specifications.11

9 Avallone, Baumeister, Mark's Standard Handbook for Mechanical Engineers, page 12-26

10 Wikipedia, Standard Penetration Test Accessed 12-4-2008

11 This helpful information is available at http://www.dot.state.il.us/materials/research/pdf/ptat4.pdf

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SOILS FOR FOOTINGS OR WALLS Soils high on hillsides tend to be shallower and coarser than those below. Very stony soils, and areas with boulders or rock ledge may be hard to dig or re-grade.

Exposed rock areas may complicate foundations. Most rocks have high bearing strength, but footings may need to be fastened to the exposed rock ledge.

Sandy soils may drain so quickly that they allow soakaways or septic systems to pollute groundwater. Sandy soils also dry out too quickly for sports fields or public lawns, although clay and humus can be added to correct this problem. Sandy or silty soils of uniform particle size may also 'liquefy' during an earthquake.

Deep soft soils can ‘amplify’ the effects of earthquakes.

Some poorly compacted materials do not provide a good base for buildings. This includes flood, landslide, and volcanic deposits as well as human debris.

Some low-lying soils that contain large proportions of plant material begin to compact when drained. Some low-lying soils of tidal areas can become highly acidic when drained, damaging structures and destroying plant life.

The stickiness of heavy clay soils make them harder to dig and re-grade. Construction in clay areas may be delayed by rainy periods, and plants may have difficulty growing. Soils that have a grayish color, or mottled spots of more or less intense color may be too frequently wet to process wastewater. Some clays shrink and swell with moisture changes and cause serious building damage.

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Chapter 3: Watch Out for Problem Soils This chapter gives a quick introduction to unusual problems. Glance through the dry climate or humid climate sections. You are in a dry climate if there is an extended dry season, or precipitation is less than 40 cm (16”) each year. Humid climates have more rainy than dry season, and receive more precipitation than 40 cm (16”)

Hopefully your land will not have any of these issues. If some of the pictures look like your land, then read carefully and follow the links to find out more.

Low Bearing Strength Soils In addition to problems from weak soils, any type of soil or rock that has been moved will settle after you build. Volcanic ash, and material deposited recently by floods or mudslides is often poorly compacted. Areas that have buried trash or agricultural wastes will settle as the materials decompose. Either re-grade these areas and methodically compact them little by little, or have footings that go through them to undisturbed soil layers.12

Landslides and Soil Creep Land and mud slides happen on hillsides, but also damage sites below. They are often caused by adding or removing soil or structures on the toe of a slope, or by the wetting of a weak layer. Sites prone to landslides include areas underlain by shale and other soft sedimentary rocks, and steep areas of clay soil. Regions with many seeps, springs, and small bogs are often subject to landslides or soil creep because a deep layer of impermeable clay prevents water drainage, and this increased soil water reduces friction between the soil layers above the clay.13

Right: Lumpy hill shapes from repeated soil creep

Tree roots provide considerable stability to steep slopes, and also reduce soil moisture levels. Trees and vegetation should be untouched and grading kept to a minimum on slopes in areas known for landslides. Slopes where fire or drought has removed vegetation may also become subject to landslide. Disturbing the base, or toe, of a slope can destabilize large amounts of soil and rock above. Sometimes small amounts of erosion at the base of a slope can begin much larger landslides.

12 Underwood, J.R. and M. Chiuini (1998) Structural Design p. 577

13 Chuck Gordon, Landslides p. 67 in Muckel, ed. (2004) Understanding Soil Risks and Hazards

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Signs of landslide activity include hummocky, dissected topography, abrupt changes in slope, trees or posts that lean, and debris in valleys and stream channels. Large scale aerial photographs may show the crescent shaped scarps and changes in vegetation created by past landslides. Stabilization measures may include replanting, redirecting runoff and/or providing drainage.14 Many slides are too large for restraining structures of concrete. Bio-stabilization measures have become standard practice using vegetation, natural materials like logs and brush, and geo-textiles.

The International Consortium on Landslides provides a world database of landslides at http://landslide-db.dpri.kyoto-u.ac.jp/landslide/simple.php which may give some indication of their frequency in different regions. More warning signs of landslides are available at http://landslides.usgs.gov/learning/prepare/.

PROBLEM SOILS OF DRY REGIONS:

Expansive Soils15 Soils high in plastic clays, and those located over some types of shale rock cause serious construction damage when their moisture levels change. Shales are layered rocks that weather and contain clay. They are commonly found in plains and on the sides of valleys, often on the best building locations in hilly or mountainous regions.16 Damage to buildings from expansive clay is common around the world.

Right: Cracked clay soil, New Mexico

Pure montmorillonite may swell up to 15 times its dry volume. Natural expansive clay soils seldom increase more than 50% of their volume, but any increase of 3% is damaging, and 10% causes severe damage to foundations, retaining walls, and other confining structures. Buildings constructed during dry periods may become cupped as the soils around the building swell and force walls to tip inward during the next wet season. Construction during wet seasons may later experience down-warping as the exterior walls slant down and out

14 Charles W. Harris, ed. Natural Hazards: Landslides and Snow Avalanches in Harris and Dine, eds. (1998) Time-Saver Standards for Landscape Architecture

15 Charles W. Harris, ed. Natural Hazards: Expansive Soils in Harris and Dine, eds. (1998)

16 Colorado Geological Survey (2004) Swelling Soils: Definition and Characteristics. Accessed 11-30-2008 at http://geosurvey.state.co.us/Default.aspx?tabid=392

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after the surrounding soil becomes more dry than the soil beneath the building. Point leaks from water pipes can cause one-sided swelling.

Existing structures in the vicinity of a new building site should be inspected for signs of damage which could indicate expansive soils, like crack lines running diagonally upward from the tops of windows and doors. Cracks in buildings and bridges, and 'rollercoaster' roads and heaved or broken utility pipes are also indicators.

Several of these soil warning signs would indicate a serious problem with expansive soils:

· The soft, puffy, popcorn appearance of clay soil when dry.

· Soil that is very sticky when wet.

· The presence of substantial open cracks in dry clay soil.

· Lack of vegetation due to heavy, clay soils.

· Soil that is very highly plastic and weak when wet, but rock hard when dry.

The problems of expansive soils are greater the higher the proportions are of expansive materials, the thicker the layers of expansive material, and the more fluctuation experienced in moisture levels. Soils that are 12% or more clay, and that have a high plasticity will be expansive. Areas that have obvious dry and wet seasons receive more damage than areas where moisture levels stay constant. Sometimes even shade cast by buildings or soil drying from plants causes heaving because of differing moisture levels.

Construction can be done safely on expansive soils, but it will usually be more expensive. Buildings on expansive clays may need expensive spread footings, or grade beams on drilled pier footings. Floor slabs are often disconnected from footings to allow vertical motion and are placed over void forms that allow the soil beneath to swell without raising the floor.

Foundations of loose rock may allow clay to expand into the spaces between rocks with less damage than a solid concrete foundation. Gravel can be used in strong plastic mesh tubes, or larger rock can be wrapped with plastic mesh fencing.

Buildings without basements are easier to modify for expansive soils than structures with sub-grade sections. Retaining walls are especially susceptible to damage. Retaining walls can be built if the expansive soil is covered with a waterproof layer, has extra drainage above, and the wall is completely backfilled with a different non-expansive soil. Stabilization plantings may be a more economical choice than retaining walls, although they require more ground area.

Another approach seeks to keep moisture levels consistent. Solid pavement one meter wide that pitches down from the building it surrounds may reduce fluctuation of soil moisture levels under the exterior walls. Consistent irrigation has also been used. But with these strategies underground utilities may require flexible connections to allow the pipes further from the house to be raised and lowered with the seasonal soil changes.

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Plants should be kept 1.7 m (5’ 6”)from a building wall, and trees at least 5 m (16’) away. Very careful treatment of surface runoff is also necessary to prevent water soaking into different areas during severe storms.17

Subsidence: Hydro-compacting Soils These difficult soils are located in arid or semi-arid plains at the base of hills or mountains, where material deposited by short but intense flash floods dried quickly without settling. These collapsible soils occur in fan-shaped layers where narrow valleys widen out. They are very porous and may be 40 – 60% empty voids. Often they form thick deposits located below more ordinary soil. When buildings are placed above collapsible soils, or the soil moisture level is increased, significant settlement can occur. Any very low density soils are cause for concern, or these signs in undeveloped plains below steeper regions:

· Small depressions in areas of fan deposits not associated with grading.

· Sinks where rainwater is gathered or retained (in areas without soluble soil or bedrock like limestone).

In developed parts of plains below steeper regions these signs should be investigated:

· Ponding and poor surface drainage.

· Curving cracks in soil or asphalt, misaligned or separated joints in concrete slabs and curbs.

· Tilted structures or evidence that cracks in structures or roads have been repaired.

Building footings cannot rest on these kinds of layers, and septic systems must be located far from buildings. Piles or posts must extend below the un-compacted soils to an undisturbed layer that has a good bearing strength.

One construction strategy is to pond or inject water or place an excessive load of fill to induce collapsing before construction begins. If the collapsible layer is not too deep, another option is to excavate and repack the material.18

Radon Gas This naturally occurring radioactive gas associated with uranium and radium occurs in glacial till and granitic rocks, and can be transmitted in groundwater. It can build up to levels that may cause lung cancer in tightly sealed houses that have basements or where showering with contaminated groundwater introduces the gas. Although sealed buildings and basements are uncommon in hot regions, buildings in rocky areas that include sub-grade construction could be tested for radon content, especially if the building will be closed sometimes for air conditioning.

17 Colorado Geological Survey (2004) Swelling Soils: Mitigation and Land Use. Accessed 11-30-2008 at http://geosurvey.state.co.us/Default.aspx?tabid=393

18 Scheffe, K.F. And S.L. Lacy (2004) Hydro-Compactible Soils p. 62 in Muckel, ed. (2004)

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Chemical Residues: Salt, Anhydrous Salts, and Gypsum Some bedrock in dry regions contains chemicals which are soluble. If groundwater is highly mineralized, or there is any record of caves in the region, sinkholes may be a possibility (see under Subsidence: Sinkholes in the Problem Soils of Humid Regions section below). Soils of bedrock areas that contain gypsum, table salt, or anhydrous salts may also contain these chemicals, which can prevent or limit plant growth and damage structures.

Right: Salty soil with white surface deposits and discolored runoff

Some agricultural regions are also developing areas of salty soil. This has been caused by modern agricultural practices that may not be common in developing areas, including using plant-killers to remove weed plants. This allows more water to penetrate past the root zones, concentrating natural salts in field runoff. In some areas where field runoff collects or subsurface drainage emerges, salt concentrations have become high enough that white residue can be seen, and standard crops cannot grow. These salty soils can cause damage to structures as well as limit agricultural use. Saline seepage can only be limited by reducing water flowing into the soil above or using salt-tolerant plantings that capture soil moisture and reduce seepage.19

Soil heaving and property damage has also been linked to the presence of special salts in the soils of mildly saline lakebeds in arid inland regions. When the temperature drops past a certain level, soils that contain anhydrous salts increase suddenly in size. They seem to require water to enable the chemical process that causes expansion, and damage can be prevented by avoiding irrigation, treating wastewater and storm runoff at some distance from structures, and monitoring for utility leaks.20

If as much as 10% gypsum is naturally present in a soil, it can dissolve and cause the soil to collapse. Gypsum can resemble white sand, but reduces the available soil fertility for plants, and deprives them of soil moisture as well. It is also caustic to structures. Abundant gypsum can cause a barren 'badlands' appearance.21

Vegetation is important to provide shade, reduce wind and wind-blown dust, and to moderate humidity and soil moisture in warm regions. If site soils do not already support a wide variety of plants, simple growing tests can be tried with the soil, using one or two quick-sprouting types of seed like radishes in soil samples, to evaluate how difficult it may be grow plants there after development.

19 Ford, J. (2004) Saline Seeps p. 83 in Muckel, ed. (2004)

20 Merkler, D. (2004) Chemical Heave and Expansive Salts, p. 11 in Muckel, ed. (2004)

21 Muckel, G. (2004) Gypsum in Excess p. 58 in Muckel, ed. (2004)

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PROBLEM SOILS OF HUMID REGIONS:

Subsidence: Organic Soils These problem soils are usually saturated peat or muck soils found in low-lying areas. Because they contain high proportions of organic plant materials, when drained these begin to decay.

Right: Rich peat soils continue to subside, including under the road

These soils will compact rapidly during the first few years after draining. Subsidence often continues at between 1 and 3 cm (1/3 to 1 inch) each year. These soils are the reason for so much of the vulnerability to flooding in New Orlean and in Holland.

Subsidence rates can be reduced (but not stopped) by allowing the soil to be saturated for longer portions of the year. Buildings require expensive piles or posts that extend below the organic material to a layer that has a good bearing strength. Connections to utility lines must also be flexible.22

Subsidence: Sinkholes Evidence of hummocky topography, or water flowing underground are cause for concern in areas with subsurface mines, lava tubes, or caves, such as karst regions.

Right: Narrow sinkhole in Kentucky, US

Karst is a type of landform found on limestone or dolostone bedrock, which includes few or sinking streams, caves, bedrock sculpted by solution, and dolines or round depressions. Humid tropical regions also include tower karst, where isolated steep walled hills are surrounded by a low-lying plain, and cockpit karst, where conical hills surround star shaped depressions. Regions that

22 Muckel, G. (2004) Subsidence of Organic Soils p. 87 in Muckel, ed. (2004)

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were covered by glaciers may have soils deposited above these characteristic shapes, but still have these groundwater systems below grade.23 See the world map of carbonate rocks in the Appendix .24 Regions with highly mineralized groundwater may also be areas of concern because similar sinkhole processes occur in areas with halite, anhydrous and gypsum bedrock, which are more common in drier regions.25

It is hard to predict where a sinkhole may appear, because they are often the result of very gradual subsurface processes that continue for long periods without visible effects. Subsidence has been caused also by the withdrawal of oil or gas in the past, but current extraction techniques reduce this risk by replacing materials with water.26 There is some evidence that heavy clay soils above caves, lava tubes, or bedrock with solution channels may be somewhat more risky places to build than lighter soils.

In some parts of the world areas with shallow soil deposits above soluble bedrock tend to gradually produce shallow and broad 'solution sinkholes'. Areas with deeper sandy soil tend to develop few and small 'cover-subsidence sinkholes', which also develop gradually. In Florida, US, areas with less permeable clay soils do not produce many sinkholes, but 'the ones that occur are deep and wide. These types of sinkholes are referred to as “cover-collapse sinkholes” because cohesive layers of sediment collapse into underground cavities when they form. The abrupt formation of sinkholes may follow extreme rain producing events...'27

Karst or carbonate bedrock areas are generally difficult to develop well. Wastewater treatment might need to be more carefully planned because bedrock solution channels are common. Karst regions often have generous supplies of groundwater, but they are vulnerable to contamination. In selecting land for development, sites with thinner or lighter soils may be more stable. But thinner soils will definitely provide less wastewater cleansing. Wastewater systems may require deeper soils than needed in areas where solution channels are uncommon.

Karst areas have been targeted worldwide for environmental preservation because their less acidic soils often support rare plants and animals. In addition these soils tend to form slowly and only support a narrow variety of plants. They are easily damaged under the drought and flooding cycles often caused by their subsurface drainage. Badly eroded karst farming areas may not recover even 20 years after damaging factors cease.28

23 Worthington Groundwater at www:worthingtongroundwater.com/karst.htm Accessed 12-4-2008

24 or online at www.sges.auckland.ac.nz/sges_research/karst.shtm

25 Hollingsworth, E. et al (2007?) Karst Regions of the World. University of Arkansas

26 Newton, D.L.(2004) Karst Landscapes p. 65 in Muckel, ed. (2004)

27 Florida Department of Environmental Protection (2008) Florida Geological Survey- Hazards- Sinkholes

28 Daoxian, Y., (1999) Rock Desertification. Institute of Karst Geology, Guilin, Guangxi, China

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Expansive Soils Expansive clays are also found in humid regions. They will require sturdier foundations and retaining walls, as well as great care with grading for drainage. These soils are not as destructive in areas that have rain all year long as they are in regions with a dry season. 29 See below under Problem Soils of Dry Regions.

Expansive soils may be available cheaply in a town under development. Although undesirable under footings or as a wall material alone, they can be used as a construction material with agricultural waste like straw. Light straw clay (LSC) is used as a thermal insulating infill wall material in areas without too high levels of termite activity.

Chemical Residues: Acid Sulfate Sediments and dredged material from the tidal edges of seacoasts are often high in iron sulfides, a material responsible for much surface water pollution from mining.

Right: Squares of barren acidic sulfate soils near mangrove forests in Guinea Bissau

Because machines enable larger land shaping operations than in the past, these soils are sometimes deposited on coastal sites. Land reclaimed from the sea may contain significant amounts. Because of the dark color of sulfidic sediments, they are sometimes confused with topsoil and mistakenly spread as a soil amendment on neighboring land.

After this chemical is exposed to oxygen, it changes from neutral to highly acidic within a few months. It is highly toxic to plants and animals, and causes erosion by killing plants that stabilized streams affected by its leachage. Aluminum and iron may be released into the environment, and sulfuric acid is produced in strong enough concentrations to damage metals and concrete in structures. 'Improper drainage of acid sulfate soils can, in effect, create an acid wasteland that is very difficult to reclaim. The soils commonly occur in nearly level, low-lying areas that are attractive sites for drainage and construction.'30 It is much simpler to avoid disturbing this type of soil than it is to repair the damage it causes.

29 Charles W. Harris, ed. Natural Hazards: Expansive Soils in Harris and Dine, eds. (1998)

30 Fanning, D.S. (2004) Acid Sulfate Soils p. 7 in Muckel, ed. (2004)

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PROBLEM SOILS OF EARTHQUAKE HAZARD AREAS:

Quake Liquefaction Risk Earthquakes can cause sand or silt to liquefy if they are saturated with water. Vibration causes the voids in the material to collapse, or the material to behave as a fluid and lose its bearing capabilities. 'Deposits most susceptible to liquefaction are... sands and silts of similar grain-size (well-sorted) in beds at least several feet thick...31 These kind of soils are common along riverbeds, beaches, dunes, and areas where wind-blown silt (loess) and sand are located.

The greatest dangers from liquefaction occur in marshes, wetlands or along shorelines where these soils are more than 60cm thick. Some areas may only have high water levels during part of the year, but earthquakes during this time can cause massive damage. Urban areas with dense construction near water bodies, and areas of reclaimed land are particularly liable to liquefaction.32

Other results of quake vibration can include lateral spreads and flow failures. Lateral spreading is most common in soils deposited in flood plains, and can cause movement of 3- 5 m (10- 15’) on nearly flat areas. Flow failures can be catastrophic, because large blocks of intact materials are moved on top of a layer of liquefied materials. They may be up to 1.5 square kilometers (0.6 square miles) , and can move at great speed. They usually involve layers of saturated sands or silts on slopes greater than 6 or 7 percent.

Some types of more expensive construction can be safe in quake hazard regions without saturated soils. These include lighter buildings with more flexible connections or squatter buildings with heavier reinforcement. But because saturated soils can undergo sudden loss of bearing strength and/or lateral movement, it is harder to design safe structures for these areas. One strategy is to attempt to improve the strength, density, and/ or drainage characteristics of the soil. If the susceptible soil is deep, (some extend as deep as 30 meters) modifying the upper 2 or 3 m (6- 10’) of soil may not be adequate.33

31 Wikipedia (2008) Soil Liquefaction Accessed 12-4-2008

32 Wikipedia (2008 ) Soil Liquefaction

33 USGS Hazards web site (2004) Liquefaction of Soils by Earthquakes p. 71 in Muckel, ed. (2004)

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Chapter 4: Shaping Buildings for the Tropics

INTRODUCTION Buildings for hot dry climates can be comfortable with thick, heavy earthen or stone walls. A 30 cm (12”) thick wall lets heat through in about 12 hours. This warms the inside of a building just as the outside is becoming cold.

It is more difficult to make buildings comfortable in hot and humid climates. The humidity is usually above 60% and often nearly 100% in many regions. With care, simple, low-cost buildings can be cool, dry, and mold-free.

Left: A breezy modern boukarou in South Africa

In hot, humid areas don’t try to shut out unpleasant weather. Electricity for fans or air conditioning is unreliable and condensation from humidity causes more problems than the heat. Open up to the breezes instead.

Peoples of hot, humid regions think of buildings as roofs and screens. Few rooms are completely ‘inside’. A sense of security and enclosure may come more from people or a compound or courtyard wall than the building walls themselves. True comfort comes from breezes which we cannot control, and the shade of a multitude of plants. Construction in hot, humid areas should cooperate with nature, use available materials, breezes and plants.

Below: Rooms with flow-through ventilation are best

Above: A screen-work corridor in India.

PLANNING FOR COMFORT Buildings in hot-humid climates need to be well ventilated, unlike those in hot-dry climates. In dry regions heavy buildings moderate the temperature. But in areas where there also is a rainy season, heavy

35

buildings of brick or concrete masonry are frequently damaged by mold growth caused by condensation.34

Often traditional local buildings provide superior comfort because of subtleties of how the materials react to temperature change or humidity.

Thick massive walls are very helpful for natural cooling when temperatures change 10 degrees Centigrade or more between night and day. Users open windows and allow cool breezes to cool off the building mass at night. During the day windows are closed and the house never heats up as much as the outside air.

Right: Rammed earth church in South Carolina, US

But hot-humid inland areas of the world usually have temperatures that rise and fall only slightly every day. Massive earthen walls do not help as much in these situations. But it can be very important to use materials like ‘raw’ (unstabilized) earth and lime plasters that do not support mold and that can moderate humidity.

Right: Chehel Sotun Palace porch, Isfahan, Iran

When large groups of people use a building in humid climates, ventilation becomes critical. Walls cannot compensate for moisture added to the air of an enclosed space by groups of people breathing and sweating. Breezes in high humidity allow people to feel cooler because of evaporation from their skin. This is why ceiling fans make people feel cooler. Breezes also replace indoor air with fresh, keeping humidity levels from building up as people exhale both moisture and heat.

Let people control their own environment, and they will feel comfortable in a wider range of conditions. Provide access to a window or vent for each person, and make shutters or blinds adjustable. Acclimatized people in hot regions tolerate hotter and more humid conditions, but cannot tolerate weather that is as cool. People from other areas living short-term in the tropics suffer more from heat and humidity than the locals.

In buildings for local users, always ask what they consider comfortable. 16 degrees Centigrade is considered a basic human need for comfort inside a building. A recent study of Nepalis living at high elevations showed that their standard temperature for comfort was nearer to 11 degrees.35 Think through your plans.36

34 Lauber (2005) Tropical Architecture. p. 101

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VENTILATION: ➔ Catch the breeze: Locate on a hill or raise above the ground, at a 20- 40 angle to the prevailing breezes.

➔ Don't block the breeze: Space buildings out, and add breezeways in them. Build a minimum of 18 m (60’) downwind from a 3 m (10’) height building or wall to allow breezes in.37

➔ Each room needs 2 exterior walls, with many windows or vents, including low openings.

➔ Verandahs with outside stairs obstruct breezes much less than interior halls.

➔ Make outdoor areas breezy: Place them on the breezy side of the building, but protected from storm winds.

➔ Porches can allow openings to windows in the center of the building.

Left: Porches ventilate

adjacent rooms.

Right: West walls can be screened with vent

block or louvers.

Right: Roof overhangs shade north and south walls at midday in the tropics

35 Hom Rijal and H. Yoshida, Winter Thermal Comfort of Residents in the Himalaya Region of Nepal, page 13

36 Many of these are explained in Koch-Nielsen (2002) Stay Cool, and in Brown and Dekay (2001) Sun, Wind and Light.

37 Koch-Nielsen (2002) page 120

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SHADING: ➔ Keep sunlight off of building walls: Try to face the long sides (with most of the windows) towards the

south and north so the roof overhang can shade walls and windows throughout the middle of the day.

➔ Shade in the afternoon: Keep west and east sides short or provide screens, vines, or shrubs to shade.

➔ Use white or light colors that stay cooler on sunny walls, roof, and pavement.

Best orientations for buildings to avoid afternoon overheating.

Above: Adjustable window screens keep sun out in Orlando, US and in Delhi, India.

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INSULATION: ➔ Keep attic heat out with a vented roof or a ceiling insulated with materials that don't soak up humidity.

➔ Use light-weight or well-insulated materials so the building won't feel hot.

➔ High ceilings let hot air rise above the people so the room feels cooler to its occupants.

PLANTINGS: ➔ Let tall, open trees shade roofs and shrubs and vines shade the ground or buildings to reduce the local

temperature. Plants cool by evaporating moisture as well as by shading, like natural air conditioners.

➔ Don't make sun traps of heavy walls around sunny paved areas. Plant between walls and paved areas.

➔ Funnel breezes with building walls or plants: Buildings close together can aim and speed up the breeze.

Right: Plants and walls can funnel breezes.

Best orientations for buildings in the southern hemisphere.

Primary goal: always avoid afternoon sun during the hottest season on building walls or windows

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Chapter 5: Building Across Cultures

COMMUNICATION Many people who help with building ideas in the tropics are from other parts of the world. This complicates understanding more than we realize. People can have very different ideas and values.

People routinely underestimate the importance of comments made by those who are not from their home culture.38 This may sometimes be from feelings of cultural superiority, but even the most humble may not understand simple connotations of statements by someone from a different cultural background.

Right: Construction training with Haitian emigres

Some people express opinions in such a mild way that more analytically-oriented people don't recognize these thoughts as important. In many cultures a 'no' answer is only polite if expressed indirectly, as 'perhaps'.39 A mild negative or a delaying tactic may actually in practice be a very definite 'no'. Try to be aware that people you work with may never express a negative in a way that you will easily notice.

Many of the peoples of the world are not analytical, don't plan ahead a lot, and focus more on who people are than what they do. Americans, other Anglos and some Europeans can seem to be materialistic and driven. Some cultures prefer simple or insubstantial building materials as a social statement of humility. Nationals may feel embarrassed for foreign designers, and avoid discussing this to avoid shaming them.

Having a neutral national friend who is willing to discuss issues and interchanges may also throw a completely different light on even official meetings that foreign helpers thought went well. Comments that may be negative or stressful could be better introduced by a third party and responses brought back by this mediator. In many places people prefer to use mediators to discuss sensitive issues with more respect.

Right: Ndebele houses show their strong identity

If nationals will be using a building, it would be best for them to supervise their own surveys about building needs or possible new shapes. They should develop a first, separate, plan for the building or buildings if possible. If buildings are to be shared, their needs and perceptions may not be well voiced once foreign helpers have begun commenting. 38 Messick, Mackie. 'Intergroup Relations' Annual Review of Psychology, vol. 40, pp. 45- 82

39 Lane, Patty (2002). A Beginner's Guide to Crossing Cultures. pages 64-66, 90-92

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The more that buildings can reflect local concepts, and be shaped by local people, the more useful, better loved and better maintained they will be. And those who participated in planning and making them will be empowered to build more in the future.

One way to build with people of other cultures is to first work with them to learn their techniques or to develop test structures. In discussions it is difficult to develop a level of caring and trust that leads to understanding. Actually getting dirty and watching and asking for help may build relationships. Anna Heringer, the architect of the Handmade School in Bangladesh (shown on page 37), started the building project by working with local craftsmen. One craftsman said: “It was good to do tests and experiment together before starting the real construction, so we could understand it although we did not know the language. And everybody learnt a lot from each other. I learned how to build strong walls, how to use measurement tools, and the foreigners learned that the best mixing machines are water buffalos.”40 Designers should desire to learn from national craftsmen and the building clients.

Right: This Cameroonian building reminds us of traditional shapes

CULTURES USE SPACES DIFFERENTLY Buildings influence us. Rooms and outdoor spaces determine our responses to each other. They can help or prevent daily interactions and the formation of friendships. If shared spaces are near entrances and main pathways, people will see and greet each other more often.

We work alone or next to others. We speak as equals or as boss and worker. We share or keep private information on papers and computer screens. Large or small groups share or restrict the use of tools, books, and work tables.

Everyone perceives intuitively the meaning of each space. The locations of the entrance, the furniture, and the windows show the hierarchical levels of the people using a room. Make sure you understand what the differences mean.41 In many cultures, showing respect is very important.

Left: Working close together often means friendship

40 Suresh, Bangladeshi loam worker, quoted at www.anna-heringer.com/index.php?id=31, Accessed 10-29-08.

41 Build Simple’s online booklet, Choose Useful Room Sizes includes sketches of different sizes and arrangements of rooms for offices and more

41

Some meanings of space are similar in many cultures. Often people feel uncomfortable sitting where others face their side. Someone seated where they look at the side of another appears to have responsibility for them. In public spaces, most people prefer to sit facing others directly.

Other ways of using space can be very different. How much space do 2 people need for a private conversation? This is different in different cultures.

Right: Working near each other or being helped Below: Meeting with someone you respect

In some groups people avoid touching each other. Americans in public spaces choose seats as far separated from others as possible. This is felt to be polite. This body language signals that they do not intend to intrude. Public etiquette is very different in other cultures.

Ask a lot of questions. What is too close? What furniture will be here?

Should desks face the door or face a wall or window? How far must a receptionist be from the waiting room seats so that she doesn’t have to chat all the time? Is there a need for a nice looking entrance and also a back door where messier activities will happen? If there are sleeping rooms, are friends ever

allowed inside? Will cooking or clothes washing happen inside the building or outside in a special space? What work spaces can be shared? Do people visit out on the porch? Will they put extra beds inside so relatives can stay with them? What uses need separate rooms or entrances for men and women?

FORM FOLLOWS FUNCTION? This famous slogan has been a driving force in design in the industrialized world for more than a century. It has been so popular because it expresses a basic assumption of many western cultures. As building designers we seek to understand what functions will take place, and develop separate shaped areas appropriate for them.

In vernacular buildings form does follow function- but the important functions may be not activities, but social exchanges or markers of status. ‘Historically, spaces in vernacular house types rarely assumed function names.

42

Actions and functions in the building were linked not to specific rooms… as much as to specific attributes … fireplace, type of window, doors…’42

Rooms or interior open spaces in buildings in many regions today are still rarely designated for a single function. In Indian houses kitchen activities spill over into the courtyard in the late morning, and in the afternoon other household chores. Cooking moves in the winter to an upper terrace, that serves as a sleeping platform in summer.43 Our orientation to rooms that are dedicated to a single function may be at odds with the frame of reference of those we are trying to build for.

Another important cultural divide is whether cultures define self-worth by achievement (function) or by status or social role. These very different orientations may motivate different room designs.44 In the efficient western office the worker often faces away from the door. Greeting and interchanges between people are more important in Asian offices where no-one sits with their back towards an entrance.

Much of how we think about buildings comes from culturally shaped presuppositions. Site planners and designers working across cultural lines should try to understand the reasons behind even simple conventions.

Cultural Building Forms Traditional Western-derived building design often emphasizes visual effect over climatic adaptation or social function. Classical symmetrical axial layouts, and Romantic or Modern assymetrical arrangements all aim for a pleasing visual composition. In many places traditional buildings and city layouts are fine-tuned to the culture and the climate in sophisticated ways quite different from those in the so-called developed countries.

Right: Colorful sunshades for a Ugandan school

Traditional buildings in many parts of the world are quite different from the west’s urban rowhouses or detached suburban homes. A courtyard or elevated dwelling compound often houses extended families in climatic comfort and privacy. Separate buildings on the sides of the site are connected by a privacy wall. The longer dimension of the site and the directions of larger buildings take advantage of desired winds or shade or sunlight. Ensuring comfort by climate-responsive locations is often a highly developed skill in vernacular buildings.

42 Habraken, N.J., (1998) The Structure of the Ordinary, page 133

43 Schoenauer, Norbert, (2000) 6,000 Years of Housing, page 182-3

44 Lingenfelter, Sherwood G. and Mayers, Ministering Cross-Culturally, 2nd edition, chapter 7.

43

Twisted, dense street networks also can provide important functions. In some places they provide protection from dusty winds. In others, an emphasis on developing a harmony with the existing land forms gives variety to cities with a geometric organization inspired by a strong ruler. Symmetrical designs sometimes occur, but building and street layouts first respond to social realities before visual ornament. A city’s streets may seem random, but often form a very sophisticated sequence of public, semipublic, and semiprivate spaces, interspersed with small squares that function as local neighborhood territory.

In the hot and dry climate of the African savannah regions traditional compact closed villages of multi-story buildings provide both protection from marauders and climate. Shade is ‘provided by tall buildings in the narrow lanes and squares and [a] barrier offered to sand and dust-carrying winds by the winding layout of the narrow routes.’45 Views are important, but involve framed glimpses that beckon into spaces beyond.

In hot and humid regions buildings were more often spaced out. In the mountains of West Cameroon compounds seemed informal, but the approach route always led through a belt of crops directly to a more public entrance courtyard, ‘guarded’ by the house of the head of the family. Passageways led between the corners of the dwelling houses to private courtyards screened on three sides by lightweight woven fencing.46

In Thailand, raised houses formed an extended-family compound. Instead of walls or fencing, elevation creates the important separation from public space. Separate houses were located around a central communal pavilion without walls. Spaces between the houses allowed access and ventilation without direct axial views into the central family space.47

Arabic-influenced cities surrounded their most important public buildings with a dense network of lanes containing shops and workshops. The mosque would be located at the intersection of two major traffic routes, but with only the mosques’ minarets or dome showing from a distance. Cities were ‘composed of squares and rectangles that can be added to indefinitely; symmetry and finality in town-planning were avoided as a challenge to that perfection which only Allah could attain’.48 Checkerboard city blocks are antithetical to the traditional cluster concept of closed precinct neighborhoods based on social affinities, not economic level.49

Right: Shaded Indian family cooking area

Entrances to compounds also reveal much about the people who live or work there. Classical western design loves axial views into the center of the building and site from an 45 Lauber page 62

46 Lauber page 43

47 Lauber page 59

48 Jellicoe, Geoffrey and Susan (1975) The Landscape of Man page 33

49 Schoenauer, page 150

44

impressive central gate. Most courtyard homes around the world turn blank walls or screened openings to the street. In some dense cities, separate shops form a street wall between simple gates into private family spaces beyond.

The primary entrance to most Asian building compounds is from a side or corner, which faces in an auspicious (and usually climatically superior) direction. The entry door faces a blank wall, which is called a ‘spirit wall’.

In many urban Chinese courtyard houses one enters the gate, and turns into an entrance porch or hall. Only if one is greeted and welcomed inside will the axial view down the center of the garden be revealed.50 The process of entering involves many layers of meaning which emphasize both privacy and formal greeting, whether an individual believes it shields the family from evil spirits or not.

An Indian house entrance may have a privacy wall blocking a direct view in, but opens into a spacious room that serves as a transitional area and a sitting room. From the far end of this room, views may open up to a courtyard, and porches, balconies, and rooms beyond. Some of the major spaces face across this axis of entry, de-emphasizing the actions of entry and leaving.51

African courtyard houses of Arabic influence also have privacy walls at the entrance. Regular internal spaces surround one or more courtyards with central water features. There may be two main axes of the house, one for public and one for private regions, but they usually are not that of the entry.52

Among sub-Saharan Africa’s tribal villages, walled compounds are common. These often appear to have randomly placed separate buildings. Obvious symmetry is not important, but because much daily life occurs in the open air, buildings define comfortable and appropriate spaces for outdoor work that reflect both physical needs and social position. The entrance to these African compounds appears somewhat random, often through a small entry space. Although the outside doorway or gate may directly face the opening into the private family area, it is never located opposite another family’s entrance, extending privacy to neighbors.

In Latin America a short covered passage connects the street entrance to the private courtyard. Privacy may be provided by wooden shutters in the double entry doors. The kitchen door is often located on axis across the courtyard to allow easy surveillance, but it does not align with the most important rooms of the house.53

50 Knapp, Ronald G., Chinese Houses, Tuttle, Singapore, 2005, page

51 Schoenauer, page 182-3

52 Schoenauer, page 150

53 Habraken (1998) page 186

45

CHANGING CULTURES Old buildings were cheap and didn’t last long. But they often reflected a deep-seated non-crisis orientation of a culture: ‘After it breaks we fix it’.

These ‘primitive’ buildings responded to the weather, the economy, and the people in many sophisticated ways. The relationships and work patterns of the people lasted longer than their buildings. The process of making buildings often taught young people how to behave and to understand their world. It was a basic personal skill, so houses seemed like a part of their own bodies.

Today people move, get different jobs, but expect houses to last. Few know how to build, many can’t afford the kind of houses they want. People spend more time inside, have more belongings, and need to lock up. Massive social and economic changes have occurred while first political and then cultural colonization have left people without much understanding of their historic culture. If your clients don’t know of viable local building styles, look for them. When someone else mentions them, they may suddenly remember. If you show they are valid, local users may be surprised and happy to think that some of their old styles are worth remembering.

In many city areas people of the tropics still spend a lot of time outside and want porches or pavilions that shade and shelter them from rain. In the countryside people still prefer to cook over wood fires, outside where it is cooler. They can afford their fuel and it works well for traditional recipes. Any designer with Western training may unconsciously overemphasize interior spaces.

Separate buildings instead of rooms are the standard in some areas, sometimes for climatic as well as social reasons. Separate wash buildings as well as toilets keep moisture and heat out of the main building. Squat toilets may be preferred in separate latrines, using more appropriate amounts of water than the flush toilet. Sometimes it takes work and creativity to discover valid cultural reasons for present day forms. The bottom line is that all buildings also have meanings. In some areas little steep roofs are only used on buildings of powerful men. Among some people piers on courtyard walls symbolize protection because they look like the ancient shrines called 'pillars of the dead' and the pinnacled mosques.54 To some, round buildings feel more like home, and remind them of their village background. Others prefer rectangular houses because they are the better 'rich people’s’ houses.

The only way to find out the meaning of buildings is to ask locals. Show photos of traditional building details or styles. Ask what these mean, and how these buildings make them feel. Ask about entrances and privacy, opinions of ornament and materials.

54 Crouch and Johnson (2001). Traditions in Architecture. Oxford: Oxford University Press page 27

46

Below left and center: Power symbols in northwest Cameroon. Below right: Mosque in Djenne, Mali.

The social structures of people in tropical areas will be either expressed in their buildings or hampered by them. It is easy to overlook the functions of space that are important in a different culture. Even if one desires to make a different statement from the one which the customary building makes, to inject a valuable new attitude or idea, only the people of that culture will be able to decide what that statement should be and how to express it.

Right: Earthen decoration by local craftsmen for India’s Hunnarshala Institute

HIDDEN COSTS Even if helpers know how to build 'better' than local people, it is best to use only a few method innovations or quality improvements in each project.55 Using complicated skills says: 'you can't do this'. Using expensive techniques says: 'your ways are poor'. It also shows a lack of concern about the very delicate economic balance that most people manage. Throwing more money into a building may mean that a family can't buy enough food during the next difficult season, or any medicine for the next sick person. This would be a tragedy compared to the much lesser problem of poor shelter in a warm climate.

Too many accidental lessons have been taught, like: 'fixing buildings is shameful'; 'nothing is worth building unless it is big;' or 'everyone needs to be alone'. It is hard to plan housing for both national and foreign staff. Foreigners too often are unable to share spaces or adapt to new ways. Nationals do deserve as good as the foreigners, but is what foreigners need good if they are (compared to the local culture) poorly socialized and overly individualistic?

Buildings should still be built as simply as possible so more can be built with limited money and local workers can copy the building styles. Laurie Baker applied a Quaker ethic to his construction work in India. His desire to 55 Coffey, Matthew (undated). Making It Stand. Colorado Springs, CO: Engineering Ministries International

avoid the showy allowed him to recreate much that was timeless in the local buildings. This resulted in work of “uncompromising simplicity; delight in the naturalness of local materials andto be boldly experimental in pursuit of cost reduction.”

Perhaps if the work is simple and uses common supplies, ordinary people may find ways to work together on their own projects. Among the Creek peoples of the US inproportionate in size to those needed for the proposed building. Several months later, when everyone had brought their share, the leader prepared them. Then all gathered to put them up and finish the buildmaterials on-site. Communities working together like this on buildings would be a good thing.

Buildings in tropical areas can be built well and beautifully and without great cost. Some new ideas can be combined with ancient traditions of responding to weather. New buildings can shelter people in ways that they need without abandoning all the beauty of their traditional building shapes. Asking about the past can enrich the future.

We want to build structures that in each local dialect, say:

‘You are welcome. Enter. Feel at home. BecomeCreator desires you to be.’

Right: Traditional decoration in Cameroon.

Below right: Non-traditional for New Mexico, this limedecoration uses an African symbol that means ‘Love will

56 Spense, Robin 'Laurie Baker- Guru of Low-Cost Housiretrieved 10-23-2008 from BDOnline at www.bdonline.co.uk/

avoid the showy allowed him to recreate much that was timeless in the local buildings. This resulted in work of “uncompromising simplicity; delight in the naturalness of local materials and craftsmanship,… and a willingness to be boldly experimental in pursuit of cost reduction.”56

Perhaps if the work is simple and uses common supplies, ordinary people may find ways to work together on their own projects. Among the Creek peoples of the US in the past a leader would pass out sticks that were proportionate in size to those needed for the proposed building. Several months later, when everyone had brought their share, the leader prepared them. Then all gathered to put them up and finish the build

together like this on buildings would be a good thing.

areas can be built well and beautifully and without great cost. Some new ideas can be ing to weather. New buildings can shelter people in ways that they

need without abandoning all the beauty of their traditional Asking about the past can enrich the future.

local dialect, say:

come all that the

: Traditional decoration in Cameroon.

traditional for New Mexico, this lime-plastered decoration uses an African symbol that means ‘Love will

triumph’.

Cost Housing' (2007). The Architect's Website. 13 April, 2007 www.bdonline.co.uk/story.asp?storyCode=3084818

47

avoid the showy allowed him to recreate much that was timeless in the local buildings. This resulted in work of and a willingness

Perhaps if the work is simple and uses common supplies, ordinary people may find ways to work together on the past a leader would pass out sticks that were

proportionate in size to those needed for the proposed building. Several months later, when everyone had brought their share, the leader prepared them. Then all gathered to put them up and finish the building with

areas can be built well and beautifully and without great cost. Some new ideas can be ing to weather. New buildings can shelter people in ways that they

13 April, 2007

48

Chapter 6: Choosing Building Materials Find out what kinds of materials are available right near your building site. Transporting materials can be very difficult in the developing world. A material that is sometimes available will slow construction and cause many delays.

Also, find out what types of skills are available as well. Workmen may not be able to travel far.

Right: Thatched Ugandan tomb monument

If you want to use a newer or alternative construction technique, pick one that is similar to some local building types. Be prepared to invest time to teach and then mentor and then supervise carefully any new or revived old technique.

LIGHTWEIGHT MATERIALS Next to cost and permanence, one of the most important goals for humid climates is usually to build of lightweight materials that don’t store much heat.57

Traditional building materials like wood, grass, palm, and bamboo are cheaper as well as cooler than masonry. But because they rot easily or are eaten by insects, they are seldom used. They could be used more often above the ground level.

Even located on upper levels, wood or bamboo posts covered by wood boards or sheetrock may rot too quickly because they never can really dry out. A less vulnerable construction technique for wood or bamboo uses a single layer of wall with exposed structure.

Some traditional and some new masonry materials are lighter and cooler than stone or concrete. Compressed earth block, open bond brick, and adobe hold less heat and suffer from less condensation damage than concrete block. Light earth is a new combination of older materials used as infill that combines the solid surface of

masonry with light, cool thermal performance.

Bamboo Bamboo is cheap since it grows quickly, being ready for building after 3- 6 years. Bamboo roof rafters can also span much further than wood. If bamboo is dried well and then given a simple smoke treatment it can last a very long time as long as it is not rained on.

Left: Desi Training Center in Bangladesh of bamboo above earth58.

57 Koch-Nielsen, p. 112

49

Bamboo works best inside, or under a wide roof overhang. It can easily be bolted if the inside is packed with a little concrete and let dry before the bolt is tightened all the way.

Wood Even if wood is not chosen for structure or walls it can be used for breathable wooden louvers, shutters, or railings. Ask older people in the villages which local woods are more durable. Wood can also be smoked to discourage

termites and mold.

Above: Breezy wood louvers for walls in a Yaounde, Cameroon church.

Wood may be available in unusual forms. Waste shipping pallets have been used to produce shutters and low-cost roof truss structures.59 Small diameter wooden poles may also be freely available or less expensive because they do not require milling. They are stronger than milled wood per cross-section area, and can be more resistant to rotting and termites.

Several types of construction in northern India, Pakistan, and Afghanistan

use frameworks of wood filled with stone and/ or earth. This patchwork or timber-laced construction is most successful in dry regions where the important wood framework does not rot inside damp stone walls. It offers important strength to survive quake vibrations.60

Left: Patchwork or dhajji dewari construction Below left: Wood basket-weave shutters.

But wood can also be used as openwork screening, or light basket work.

58 Anna Heringer and Eike Roswag, Aga Khan Award, http://www.akdn.org/architecture/pdf/3392_Ban.pdf

59 von Bachmayr, Alfred (undated). The Pallet Truss. Retrieved from Builders Without Borders Web site: www.builderswithoutborders.org/PUBLICATIONS/PUB6.htm

60 Langenbach, Rudolf (2009). Don’t Tear It Down! Preserving the Earthquake Resistant Vernacular Architecture of Kashmir, Unesco, New Delhi.

Natural Fibers Other lightweight materials are useful for upper stories or to screen large openings in exterior walls.These can include natural reeds and grass, or agricultural waste like roots.

Traditional thatch tied reeds or grass on walls. Wand daub used some straw mixed with clay on frameworks of wooden poles.

Modern versions use an insulating straw mixture inside of a latticework (bahareque), or straw stuffed into strong mesh tubes and soaked in clay (straw wattle). These can both receive smooth earthen and lime plaster.

Above right: Traditional thatched house in CameroonBelow right: Straw wattle dormitory in Haiti

Light Straw Clay (LSC) is used in North America and Europe as an infill material in high end wood-framed homes. It can have a high r-value, and is often built 10” thick for cold climates.

The clay-soaked straw sets up quickly after being lightly pressed into simple forms. In warmer regions it is used with light wood poles as interior non-load bearing walls.

Below left: LSC infill for a wood-framed house

are useful for upper stories or to screen large openings in exterior walls.

tied reeds or grass on walls. Wattle on rough

Modern versions use an insulating straw mixture , or straw stuffed

straw These can both receive smooth earthen and

ight: Traditional thatched house in Cameroon ight: Straw wattle dormitory in Haiti

Light Straw Clay (LSC) is used in North America and framed

value, and is often built

soaked straw sets up quickly after being lightly pressed into simple forms. In warmer regions it is load bearing walls.

framed house; Below right: Rolls of LSC in burlap for roof insulation in India

50

soaked straw sets up quickly after being lightly pressed into simple forms. In warmer regions it is also

; Below right: Rolls of LSC in burlap for roof insulation in India

51

ROOFS AND INSULATION Traditional reed thatched roofs are cool, quiet, and last up to 40 years. Some people have begun making thatch in modular units assembled on the ground, which are more easily installed. This might be best for only moderately humid areas, since moldy thatch can cause health problems.

Many people prefer galvanized metal roofs because they won't burn and keep rain out more completely for longer. Metal roofs are relatively inexpensive although they can be very noisy in a heavy rain and hot in sunny conditions. White, if available, is much cooler.

Natural materials can be used inside buildings to provide sound or heat insulation. Sea grass or rice hulls have potential because they don't absorb much humidity. Any of these can be used in breathable common poly rice bags.

Rice hulls, left over from growing rice to eat, don't burn very easily, and have an R-value of around 3 per inch.61 But any loose fill can have rodents invade, and is only useful in well-sealed houses with shutters and/ or screens.

Coconut fibers also do not absorb a lot of humidity. They are sometimes made into thick mats, but need to be treated with a simple fire retardant like borate.

Any of these may work well under a metal roof. Wire or plastic mesh can be fastened between collar ties or under roof trusses to hold insulation in bags. Woven grass mats or fabric fastened below them would make an inexpensive, attractive ceiling.

Above: Rice hulls in bags to insulate, with woven mats hung below bags for ceiling.

Right: Traditional Danish eelgrass roof

Sea grass is a type of seaweed that is harvested from beaches where it washes up and can be made into batts or pellets. Its natural high salt content is a fire retardant. Other types of seaweed, including eelgrass, have been used in colder climates to form water-resistant roofs and building walls.62 A small island deforested centuries ago by fuel for salt production,

61 Geiger, Owen and Kelly Hart (2008) Using Earthbags as Ceiling Insulation. Accessed 12-12-08 at www.earthbagbuilding.com/articles/ceilings.htm

62 See Byg’s work on the island of Laeso in Denmark, online at http://www.dezeen.com/2013/07/10/the-modern-seaweed-house-by-vandkunsten-and-realdania/

52

Laesǿ in Denmark has some roofs that are 400 years old. Modern architects have also used eelgrass for insulating walls.

HEAVY MASONRY People want houses that last, don't burn, and keeps insects, rodents, and thieves out. Stone and brick walls have been used for beautiful buildings worldwide. Many people build with concrete now, because these buildings seem modern, last a long time, and are cheaper and easier to build than brick or stone. They keep mosquitoes out better than wood buildings.

For some people “Their dream house is of concrete, like the houses they see belonging to the rich. Even if they know they will sacrifice comfort and coolness during the day, or that they will never be able to afford that dream house, they do not care. They will wait for the day when they can have a 'real house'...” 63

Unfortunately, the cost of concrete buildings is very high in the developing world. Although US laborers can work an hour to earn a bag of Portland, African laborers may have to work one or two days for each bag. Developing world builders are often tempted to use thinner mixes or less reinforcing steel because of the high costs of these manufactured materials. This watered down building material is the main cause of many disasters world wide.

Right: Damaged reinforced concrete, Haiti

Right: Multiple story earth buildings in Yemen

If you are building in a seismic risk zone, making heavy masonry strong enough will limit the types of construction you can use. Find out about confined masonry64 and other types of reinforcement.

The majority of permanent buildings through-out history have been built of earth. It doesn't burn, keeps pests and thieves out, is inexpensive and widely available. This flexible and beautiful material is being revived and becoming more generally accepted partly because of its excellent thermal

63 Steen, Bill and Athena. 'Straw, Clay and Carrizo' in Elizabeth and Adams (2005). Alternative Construction. NY: John Wiley and Sons.

64 Mario Rodriguez, Confined Masonry Introduction, World Housing Encyclopedia, http://www.world-housing.net/major-construction-types/confined-masonry-introduction

53

performance.

There are many ways to use earth. Buildings can be made of raw unbaked earth alone in massive cob walls or in individual mud blocks (also called adobe). Plain earth or earth with a little lime or cement or bitumen can be used in rammed earth walls or compressed earth blocks (CEBs). Or earth can be poured into sandbags and stacked for earthbag walls, in what has been called the cheapest building method on earth.

Above: New earth building in Thailand.

Earth buildings last well when maintained. Raw earth buildings need to be protected from rain and flooding to work well in humid climates. A good roof and a dry base of stone or concrete are very important. Outside walls of raw earth that get rained on should be re-plastered every few years unless they have special coatings. But most important is raising earth construction 50 cm or more above the ground in rainy areas, and using a good vapor barrier.

Humidity in Earth Buildings Many people don't realize that raw earth buildings are healthier than concrete in high humidity regions.

Earthen buildings never absorb enough water to let mold grow on them like concrete does. The most dampness they absorb from the air (5- 7% by weight) is not enough to let insects or mold grow (which need between 14 and 20%).65

Very humid air is often near its dew-point in tropical regions. Every time that damp air warms up just a little more than a building, moisture in it condenses on the slightly cooler surface. Heavy concrete walls in very humid areas become frequently damp from condensation, causing algae or mold growth.

Thick walls built of ‘raw’ earth and stone materials can absorb humidity. But earthen walls never become damp enough to support interior molds or allow embedded protected wood or metal to decay from moisture.

Right: Rammed earth stores solar heat, New Mexico, US

Museums use this characteristic to equalize humidity changes for delicate collections. Libraries and computer equipment rooms have recently begun to take advantage of these qualities of thick earthen walls. Earthen walls without a

65 Minke, 2006, pp. 14- 15

cement stucco coating can reduce maximum humidity levels inside a building. For humidity reduction, it is important that all plasters and paints be of materials that can ‘breathe’. Do not use modern latex or other sealants. Historic lime-based plasters used throughout the mediterannean, and Europe for interior and exterior surfaces allow humidity to pass through. Lime plaster is also alkaline enough that it is antiseptic and kills molds. Lime surfaces grow stronger over

time, and is easy to repair. Small cracks self-heal, and liquid limewash can be used to improve surfaces worn by weather.

Above right: Earthen plasterBelow right: Textured lime plaster

Gypsum-based interior plasters also allow walls to breathe and moderate humidity. Modern clay-based earthen plasters and ‘alis’ paints are another alternative. If local people think that earthen plasters for interior walls are low quality, they should see someexamples, like the photos on the American Clay company website, at http://www.americanclay.com/.

Many countries are beginning to include earth buildings in their building codes.apply unnecessary rules and make buildings morcode, you are free to build strong but cheaply. The earth buildings common in wet countries, like the UK and Germany, have lasted hundreds of years without following building codes.

Earth buildings can be finished with traditional windows and doors.

66 New Zealand and the Ivory Coast, among others, as well as states like New Mexico in the southwestern US.

cement stucco coating can reduce maximum humidity levels inside

For humidity reduction, it is important that all plasters and paints terials that can ‘breathe’. Do not use modern latex or

based plasters used throughout the mediterannean, and Europe for interior and exterior surfaces allow humidity to pass through. Lime plaster is also alkaline enough that t is antiseptic and kills molds. Lime surfaces grow stronger over

heal, and liquid limewash can be used to improve surfaces worn by weather.

Above right: Earthen plaster Below right: Textured lime plaster

based interior plasters also allow walls to breathe and based earthen plasters and ‘alis’

paints are another alternative. If local people think that earthen plasters for interior walls are low quality, they should see some examples, like the photos on the American Clay company website,

Many countries are beginning to include earth buildings in their building codes.66 Unfortunately, some codes apply unnecessary rules and make buildings more expensive without being safer. If your area does not have a code, you are free to build strong but cheaply. The earth buildings common in wet countries, like the UK and Germany, have lasted hundreds of years without following building codes.

ings can be finished with traditional windows and doors. Although they may feel much more comfortable, modern earth buildings may not look any different from structures built of brick or concrete or stone.

Left: Wood window forms in Haitian earthbag

Thermal Mass Hassan Fathy tested equally sized buildings inmoderately humid climate of Cairo, Egypt in 1964. On a March day the temperature varied between 12 and 28

New Zealand and the Ivory Coast, among others, as well as states like New Mexico in the southwestern US.

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Unfortunately, some codes e expensive without being safer. If your area does not have a

code, you are free to build strong but cheaply. The earth buildings common in wet countries, like the UK and

more comfortable, modern earth buildings may not look any different from structures built of brick or concrete or

Left: Wood window forms in Haitian earthbag

Hassan Fathy tested equally sized buildings in the hot, in 1964. On a

March day the temperature varied between 12 and 28° C.

New Zealand and the Ivory Coast, among others, as well as states like New Mexico in the southwestern US.

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A building of 50 cm (20”) thick mud block with a vaulted mud block roof only stayed a comfortable 21 to 23° C inside. A similar building of 10 cm (4”) thick precast concrete walls and roof became 9° C hotter inside than out. Overall it was within the human comfort temperature range for only 5 hours out of 24. Because the mud block held more heat, it warmed up slowly in the morning, and cooled off slowly at night. It also insulated much better than the concrete, and may have reflected more sunlight (depending on surface finish).67

Materials work well in hot, very humid weather if they don't hold much heat and are well insulated.68 Fathy’s type of heavy earthen masonry building will be better than a concrete block building for humid inland regions of the tropics. But light weight materials may be better. CEBs have become widely popular because their lighter construction holds less heat than fired bricks and concrete CMUs, while also insulating the building better from outside temperature changes. This results in a cooler daytime temperature as well as less condensation during the early morning hours.

How common building materials compare at holding heat, insulating, and cost: Material- thickness

Holds less heat than earthbag (btu/in/8F)

Reflects more sunlight than bricks/ CMU

Insulates better than solid concrete (R val.)

Costs Less than solid concrete

Solid poured concrete- 15cm

2.7 times better (15) Smooth: 35% Insulates the worst (0.5)

Greatly > materials + skilled labor

Fired bricks- rat trap 20 cm

4 times better (10) Regular dark: 20% 2.8 times better (1.4) > materials + mason

Hollow conc. block- 20cm

5 times better (8) Rough stucco: 20%

2.2 times better (1.1) Standard with mason

CEB- 20cm 2.4 times better (17) Light: 40% 4.4 times better (2.2) <materials + mason Mud block or cob- 40cm

1.2 times better (33) Light plaster: 40%+

8.8 times better (4.4) 33% materials? + mason

Earth in earthbag- 48 cm

Holds most heat- (40)

Light plaster: 40%+

10 times better (5.3) Cheapest: site mat’ls + unskilled labor

One alternative can make earthen walls hold about as little heat as CEBs, but be much better insulated. This is when light gravels (naturally occurring volcanic scoria) are mixed with earth. This material, called light earth, combined with the low cost of earthbag construction techniques, may be the best material for humid tropics.

Only bare CEBs will perform exactly according to this table. These figures are for the basic materials, not including reinforcement or plasters. Clay plasters needed on the exterior of mud block and both sides of earthbag do not hold much heat. Cement stucco usually applied to hollow concrete block (CMU) holds a little 67 Fathy, Hassan (1986), Natural Energy and Vernacular Architecture. In part 3, Building Materials. Available online at www.nzdl.sadl.uleth.ca

68 This table has been assembled from data in Stay Cool, Building with Earth , and the Passive Solar Energy Book

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more. Since CMU walls are sometimes installed partially filled with cement and rebar, or more often as infill with solid concrete bond beams and posts, they may not perform as well as these figures indicate.

An actual test of small comparison buildings should be made in the humid tropics, similar to Fathy’s test. Interior air temperatures could be compared to wall surface temperatures. Some indication of the amount of condensation received would be extremely helpful. The performance of different surface finishes should also be made for condensation in interiors and reflectance of sunlight on exterior walls.

COMPARING SUSTAINABLE WALLS The costs of earth building materials are very low. A single story school built in the Philippines using earthbag with a reinforced cement vaulted roof cost 40% of the standard building costs for CMUs.69 But construction materials may be chosen because of the availability of related materials, supplies, tools, or skills.70

Adobe CEB Earthbag Light Straw Clay

Rammed Earth

Compressed Trash Blocks

Skilled workers + ++ + ++ Costly tools/ Equipmt ++ + ++ ++ Sand + Sandy soil + + + + Clay soil + ++ Immediate process + Thick walls + + ++ Reinforced Can be Confined + + Can be + Insulating + + Structural wall + + ++ ++ + Need plaster + + + Water-resistant if: Stabilized Stabilized Sand or

gravel fill Stabilized Water-

resistant stucco

69 Built by Abakada at Barabgay, Phillipines from www.earthbagbuilding.com/projects/school.htm

70 Some information from Owen Geiger of www.naturalbuildingblog.com

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Stabilized earth materials’ costs are controlled mostly by the cost of the stabilizer. Although earth construction of cement stabilized mud block or CEB use only 20% as much Portland cement as poured concrete and CMUs, they still use about 5% cement by volume. For buildings with porches and/ or roof overhangs, exterior walls of pure unstabilized earth are both practical and inexpensive.

EARTHBAG Earthbags are a simpler way to build with earth, using the strength of woven fabric bags while the earth dries. Because it is tamped, it has some of the properties of rammed earth without the need for heavy forms. Earthbag is finished with a plaster layer of earth materials and/ or cement or lime.

Right: Barbed wire adds strength to earthbags.

Earthbag building works well with a greater range of soils than most other earth techniques, between 5% and 30% clay.71 Earthbags can also be built of sand, gravel, or soil without clay, if they use some bamboo, wood, or steel reinforcement, or have a plaster of cement stucco.

Brick, concrete block, poured concrete, and earth blocks are much more expensive than earthbag. They also require more accurate mixes of materials and better trained labor than earthbag. Because earthbag is placed in large units (standard bags are 48x60x15 cm or 19X24X5”), construction proceeds quickly. Three untrained people take about an hour to lay one square meter (11 sf) of wall.72

BRICK Common fired bricks are the most well-known earth material. They can make versatile thin walls. Solid brick works best where walls are shaded by plants or other buildings, because they do not insulate well. Rat trap bond

stands bricks on edge around a hollow center. It uses 25% more brick than a solid single layer wall, but because it creates a hollow wall, in parts of India it is known to keep building temperatures inside 58 C lower than outside.73

Above: Brick openwork 71 Hunter, Kaki and Kiffmeyer, Donald (2004). Earthbag Building., page. 17

72 More information on building with earthbags for humid regions is available at www.earthbagbuilding.com /pdf/earthbagbuilding2.pdf. For buildings in seismic risk regions, check www.BuildSimple.org for information on contained earth walls that use engineering wisdom for safety in risky areas.

73 Sanghi, Preeti (2006). 'Rat-Trap Bond for Walls'. Architecture for Development, 2 November 2006 at www.archidev.org/articles

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Brick can be formed into beautiful openwork “jali”, as Laurie Baker created in India. Jali lets in subdued light, allows ventilation and glimpses out, but keeps the inside private and secure. Small scale jali keep driving rain out, but may cost only 10% as much as a window.74

Low-fired bricks absorb more water than common fired brick. They are cheap, often fired with waste rice hulls. They can be used for inside walls, or outside with special finish coats.

COMPRESSED EARTH BLOCK Compressed earth blocks (CEBs) use earth with about 5- 10% clay. They are usually 2.5 times thicker than fired bricks, but they insulate better and moderate humidity better than fired bricks. These smaller blocks require more time for construction than the larger concrete CMUs.

Right: A CEB school in Burkina Faso. Below right: A CEB press.

Because CEBs are less expensive than fired brick, and can be produced by individuals with simple equipment, these blocks are improving living conditions in many countries. In humid regions they must be either stabilized or protected by a substantial roof overhang.

CEBs produced with bitumen or cement cost more than raw blocks. The quality of individual production should be pre-tested before use in exposed areas, because poorly stabilized CEBs can be damaged by absorbing too much moisture. Stabilized CEBs can be coated with cement plaster.

MUD BLOCK Unbaked mud block (or adobe) is usually built by masons, but is twice as thick as CEB walls. It is inexpensive because it does not require fuel or sophisticated equipment.

Because of mud block’s historic usage, basic rules of strength for unreinforced construction are well accepted for regions not subject to earthquake hazard. In regions with medium or high risk of earthquakes, some sort of reinforcement may be necessary. Mud block can be used there as infill between concrete posts. Historic structures of mud block have been built up to 8 stories, but is usually only used today up to 2 stories. It

74 Baker, Laurie. Rural House Plans. www.laurie-baker.net/work/work/booklets-and-writing-by-laurie-baker.html

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is strongest if built of short wall segments that include piers or corners. Windows should be spaced at least 1m (39”) from corners, and 1m (39”) apart unless a pier is located between windows. Corbelled window openings can be built without lintels.

Right: Buttresses and walls that jog brace earth

buildings. Far right: Piers between

windows.

Mud block requires water resistant mud plaster on exterior walls that must be renewed every few years. Like all raw earth construction, mud block should not be covered with concrete stucco. The concrete retains too much moisture and will decay the mud block. This material is a good choice for interior walls and furnishings, especially in buildings where reduced humidity is needed to preserve materials, like museums, libraries, and computer centers. Mud block walls are easier to clean and still retain much of their humidity-modifying properties if finished with a lime-plaster or tiled surface, or coated with a natural oil finish.

RAMMED EARTH Solid earth with the right mix of particle size can be rammed to higher strength. The fill is only lightly dampened.

Rammed earth walls are traditional techniques in some regions. Hand tamping has been used on the Great Wall of China. Machine tamping (with pressure hoses) is used in modern France.

Rammed earth walls require a carefully tested soil mix, and large forms to hold the earth. Often rammed earth is built fully stabilized so that no plaster is needed for exterior walls. Rammed earth walls are often strong enough to build in multiple stories.

Right: German rammed earth building from the late 1800s Rammed earth walls can be reinforced with included vertical steel rods for seismic risk areas.

COB Clay soils can be built as cob. These massive walls are built wet and dry slowly. Usually only 90 cm (3’) in height can be built before stopping and letting the wall cure and harden.

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Cob walls are traditional in many parts of Africa. They are built of hand sized loafs of mud, mixed with straw. These loafs are applied without forms. The hand building process lends itself to curving walls and applied decorative shapes.

Below right: Cob wall construction

Since cob walls must be thick to be strong they may receive more condensation than CEBs.

CMU INFILL vs. CONFINED MASONRY The most common solution for those with enough money in warm, humid areas is to use weak, hollow concrete masonry infill between poured concrete posts and beams. These buildings don't heat up as much as solid masonry, and if painted with waterproof paints the inside walls can be scrubbed.

In the US and Europe hollow CMUs are made strong enough for structural use, or poured solid with concrete. The lighter, weaker blocks available in hot regions, sometimes called sand cement blocks, are better at insulating than at holding up roofs. Very strong columns and beams are needed for a safe building.

Right: Smooth concrete columns poured first Below right: Concrete blocks built inside the columns

Increasing prices of steel and concrete, and unreliable concrete supplies complicate this type of building. In Africa, South America and Asia cement may be too valuable a commodity for common use. In the US a laborer works about half an hour to earn a bag of cement. In other countries it may take a laborer 3 days or more to earn the same bag.

Maintenance costs of repainting and scrubbing interior walls need to be considered before building with concrete. Additional intangible costs will also include discomfort from hot buildings, belongings ruined by mold growth, and health damage from living with mold. Overall, concrete buildings may not be the best choice for hot and humid climates.

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It is common practice in many places for workers to use less concrete in the mix, and save bags out to use at home or resell. Concrete may not be right for places where public officials expect gifts, workers often 'borrow' supplies, and people are accustomed to more forgiving rule-of-thumb type work than high precision measurement.

Left: Confined masonry construction Below right: Tie columns and beams in confined masonry

Confined masonry uses moderately strong bricks or blocks. It adds more but smaller tie-columns and tie-beams.

For confined masonry the blocks are built first by skilled masons, leaving gaps for tie-columns. The gaps have zig-zag edges, making the walls connect well to the columns and help hold up the roof weight. After the block work is done, forms are added outside the walls and steel reinforced concrete columns and bond beams are poured in between .

Confined masonry is more cost-effective than poured concrete or reinforced concrete post and beam structures in areas subject to earthquakes. Guidelines have been created about using confined masonry with brick or concrete block in many languages.75

75 World Housing Encyclopedia, Confined Masonry Introduction, http://www.world-

housing.net/major-construction-types/confined-masonry-introduction

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Appendix: Regional Hazard Maps

Seismic Hazard The first hazard to check is seismic risk. The US Geological Survey’s GSHAP maps (shown below) are somewhat out of date, but a quick glance can tell you whether you need to do further research. White or green denote areas of very low seismic risk. Yellow or orange are moderate risk. Red is high, and brown to black are very high risk.

Regional maps can help you to see which level of risk the GSHAP shows for your area. See images at right and on the following page.

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Higher risk areas are likely to experience larger earthquakes sooner than low risk areas. Yet the costs to build safely enough to survive any possible event may prohibit building.

Aid planners should try to improve on the currently accepted level of construction quality. Yet often it is important to let local users gain real or assumed ownership of a building. Construction technologies that are so expensive and/ or complex that local clients could never conceive of building tends to prevent this.

People may not have heard that they live in an area with seismic risks. They may have a cultural background that does not

plan for future possibilities, and no experience with this way of thinking. Ask whether their area has had problems from earthquakes in the past. Sometimes showing them information about past events in their area can be helpful.

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If a project site is located in areas shown on the GSHAP maps as yellow, orange, red or brown, it is critical to know the exact level of risk. Look for hazard maps developed by the national government. One other resource is to use the USGS’s current online web data, their Global Seismic Design Tool. This is located at http://earthquake.usgs.gov/hazards/designmaps/wwdesign.php.

Click to launch the tool. You can either enter the coordinates, or if you zoom in to grab their place marker, you can move it around.

Information is listed in a small chart in multiple formats. Numbers that are in a green box are more recent than those in a red box. The Ss numbers relate to one and two story buildings.

Types of Buildings for Seismic Risk Levels Engineers can give you much more accurate information than what follows. Also, please realize that the shape and locations of openings can make buildings unsafe or safe for earthquakes.

Any values less than 0.3 indicate that low-strength buildings like local earth and unreinforced brick or stone should be safe.

Values between 0.3 and 0.6 indicate that careful planning and some reinforcement can allow you to build safely with low-strength materials. In New Zealand, some basic plan requirements for two story moderate size buildings have allowed the use unreinforced earth. For this level of risk New Zealand requires a good reinforced concrete footing and a strong wood or concrete bond beam on top of the building. New Zealand is mentioned, because their code has a unique system for designing buildings without engineers. Severe recent earthquakes have also confirmed that their code provisions save buildings.

Values greater than 0.6 show that light-weight or stronger buildings are important. In these areas it’s worthwhile to do a little research and get some help.

Wood buildings with light roofs that are built carefully resist earthquakes well. Confined masonry is a cheaper way to reinforce bricks or compressed earth blocks (CEB) than the standard western reinforced concrete building. There are many ways to reinforce other materials.

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Other Hazards What is the limiting factor in the area of your project? This information may be so basic to life for local residents that they wouldn’t think of mentioning it.

Is there enough rainfall for crops? Is the heat so intense that people stay inside during sunny days? Are rains so heavy that buildings are often damaged? Are soils so hard that they can’t be dug?

The map above from the US Natural Resources Conservation Service (NRCS) is available in a large file size online at http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/use/worldsoils/?cid=nrcs142p2_054020. Have a glance at this information. More detailed maps of regions may be available online, like the map of Africa on the next page.

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Limestone-derived bedrock can cause difficult conditions for plant growth, as well as occasional sinkholes. When surface water trickles into underground passageways, once in a while it decays the subsoil and rocks in a large area. You may want to have an idea of whether that might happen in your region. The map of carbonate rock occurrence below may give you a hint of whether to look for a more detailed map for your areas.

Any large scale map may be helpful if it gives an outsider some clues about life in a region. Climate averages, rainfall intensity, hurricane winds, natural vegetation. Don’t forget that simple topography is also important. Do your research before you recommend buildings on a visit to a distant location.

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BIBLIOGRAPHY

Chapter 1: Looking for Land Harris, C. W. and N. T. Dines. Time-Saver Standards for Landscape Architecture,second edition. Mc-Graw-Hill Publishing Company, NY, 1998.

Websites:

Catholic Relief Services developed the arborloo- see http://crs-blog.org/world-toilet-day-arbor-loos-do-double-duty/. More Arborloo information is online at http://www.sswm.info/category/implementation-tools/water-use/hardware/toilet-systems/arborloo#reference_book7934

Peepoople.com has simple information on the PeePoo aimed at users. www.peepoople.com

Soil is an NPO that has been working with the ecosan composting toilet in Haiti. See information on https://www.oursoil.org/

Sustainable Soil and Water Management has information about many sanitation issues at www.sswm.info , including the Arborloo, the PeePoo sanitation systems, and more

Tippy Tap.org has a simple how-to pdf for this simple hand-washing station at http://www.tippytap.org/wp-content/uploads/2011/03/How-to-build-a-tippy-tap-manual.pdf.

Engineering Ministries International has many resources under their volunteer links. Their Developing World Design powerpoint is a great place to start. Look through all of their architectural and engineering resources at http://www.emiworld.org/volunteer_resources.php

Chapters 2 & 3: Preliminary Soil Evaluations and Problem Soils Avallone, Eugene A., and Theodore Baumeister III, Mark's Standard Handbook for Mechanical Engineers, 10th edition. Mc-Graw Hill, NY, 1996.

Bell, F.G., ed. Ground Engineer's Reference Book. Butterworth's, London, England, 1987.

Bohan, Heidi, Quick and Easy Habitat Education Activities: Soil Assessment 1- Composition. Starflower Foundation, http://www.wnps.org/education/resources/documents/garden_links/5-7_soil_assessment.pdf accessed 10-21-15.

Gaylord, Edwin H., Jr. and Charles N. Gaylord, eds. Structural Engineering Handbook, 3rd edition. McGraw Hill, NY, 1990.

Lindeburg, Michael R. Civil Engineering Reference Manual for the PE Exam, 9th edition. Professional Publications, Belmont, CA, 2003.

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Minke, Gernot. Building with Earth: Design and Technology of a Sustainable Architecture, Birkhauser, Basel, Germany, 2006.

Muckle, Gary B. (ed.). Understanding Soil Risks and Hazards: Using Soil Survey to Identify Areas with Risks and Hazards to Human Life and Property. US Department of Agriculture, Natural Resources Conservation Service, National Soil Survey Center, Lincoln, Nebraska, 2004 Available online at http://soils.usda.gov/use/risks.html

Schoeneberger, P.J., Wysocki, D.A., Benham, E.C., and Broderson, W.D. (editors). Field Book for Describing and Sampling Soils, version3.0. Natural Resources Conservation Service, National Soil Survey Center, US Department of Agriculture, Lincoln, NE, 2002 Available online at http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/research/guide/?cid=nrcs142p2_054184

Underwood, R. and M. Chiuini. Structural Design: A Practical Guide for Architects. John Wiley & Sons, NY, 1998.

Websites:

Florida Department of Environmental Protection http://www.dep.state.fl.us/geology/geologictopics/

US Department of Agriculture Natural Resource Conservation Service Technical References: http://www.nrcs.usda.gov/wps/portal/nrcs/main/soils/ref/

Chapter 4: Shaping Buildings for Climate Brown, G.Z. And Dekay, Mark, Sun, Wind & Light: Architectural Design Strategies, 2nd edition. John Wiley and Sons, NY, 2001. A valuable desk reference for building design in all climates.

Fathy, Hassan, Natural Energy and Vernacular Architecture: Principles and Examples with Reference to Hot Arid Climates, UNU, 1986. Available online in the Community Development Library of the University of Waikato at www.nzdl.sadl.uleth.ca

Goad, Philip, Troppo Architects Periplus, Singapore, 2005. Work by Glenn Murcutt and office in Australia.

Koch-Nielsen, Holger, Stay Cool: A Design Guide for the Built Environments in Hot Climates. London, UK: James and James, 2002. This small, practical book is helpful for both hot humid and hot dry regions.

Lauber, Wolfgang, Tropical Architecture: Sustainable and Humane Building in Africa, Latin America and South-East Asisa. Munich, Germany: Prestel, 2005. Traditional climate-responsive buildings and new unresponsive.

Stouter, Patti, Shaping Buildings for the Humid Tropics: Climate, Culture, Materials, web publication, 2008. Available at www.earthbagbuilding.com/pdf/shapingbuildings1.pdf

Websites:

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The Gando schools and other projects by Diébédo Francis Kéré are posted on his office website http://www.kere-architecture.com/projects/

Chapter 5: Building Across Cultures Coffey, Matthew (undated). Making It Stand. Colorado Springs, CO: Engineering Ministries International

Crouch, Dora P. and Johnson, June, Traditions in Architecture: Africa, America, Asia, and Oceania. Oxford, UK: Oxford University Press, 2001. Essays on some cultural issues of vernacular buildings.

Habraken, N.J., The Structure of the Ordinary: Form and Control in the Built Environment, MIT Press, Cambridge MA, 1998.

Jellicoe, Geoffrey and Susan, The Landscape of Man: Shaping the Environment from Prehistory to the Present Day, Van Nostrand Reinhold, NY, 1982. History of cultures and landscape design including Africa and Asia.

Lane, Patty, A Beginner's Guide to Crossing Cultures. Intervarsity Press, Downer's Grove, IL, 2002. Tips for working across cultures, with some comparative information on values common in different countries.

Lingenfelter, Sherwood G. and Marvin K. Mayers, Ministering Cross-Culturally: An Incarnational Model for Personal Relationships, 2nd edition, Baker Academic, Grand Rapids, MI, 2003. Discussion of working with basic cultural differences of goals and worldview.

Schoenauer, Norbert, 6,000 Years of Housing, W.W. Norton, NY, 2000. Sketches and discussion of houses.

Steen, Bill and Athena, and Eiko Komats, Built by Hand. Gibbs Smith, 2003. Vernacular buildings of the world.

Stouter, Patti, Choose Useful Room Sizes, free ebook, 2012. Sketches and discussion of space use and sizes needed in offices, schoolrooms, and other spaces. Available at http://buildsimple.org/resources/Choose%20Room%20Sizes.pdf

Chapter 6: Choosing Materials Baker, Laurie. Rural House Plans. These and other booklets are available free at his website at www.laurie-baker.net/work/work/booklets-and-writing-by-laurie-baker.html.

Bengoechia, Isabella. Sustainable Architecture in Burkina Faso, The Culture Trip accessed online 10/27/2015 at http://theculturetrip.com/africa/burkina-faso/articles/di-b-do-francis-k-r-sustainable-architecture-in-burkina-faso/.

Chugh, Rashi. Works of Laurie Baker. Slide show http://www.slideshare.net/rashichugh52/works-of-laurie-baker

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Elizabeth and Adam. Alternative Construction. John Wiley and Sons, NY, 2005. Discusses earth and straw.

Fathy, Hassan, Natural Energy and Vernacular Architecture, UNU, 1986. Available online at http://unu.edu/publications/books/natural-energy-and-vernacular-architecture-principles-and-examples-with-reference-to-hot-arid-climates.html

Geiger, Owen, Earthbag Building Step by Step: Vertical Walls. Online ebook. http://www.naturalbuildingblog.com/owens-book-dvd/

Hunter, Kaki and Kiffmeyer, Donald , Earthbag Building. New Society Publishers, Gabriola Island, 2004. In-depth how-to manual for earthbag construction.

Minke, Gernot (2006). Building With Earth: Design and Technology of a Sustainable Architecture. Basel: Birkhauser. Comparison of the technology of mud block, rammed earth, cob with some earthbag.

New Zealand, Materials and Workmanship for Earth Buildings: Volume 3- NZS4299 Earth Buildings not Requiring Specific Design, 1998

Stulz, R. , Appropriate Building Materials: A Catalog of Potential Solutions, SKAT, 1998. Available http://collections.infocollections.org/ukedu/en/d/Jsk01ae/

Websites:

Builders Without Borders at http://builderswithoutborders.org/resources/index.htm

Build Simple Inc. includes manuals and testing regarding geo-textile alternative construction techniques and information about site planning and culturally appropriate aid building. http://buildsimple.org/resource-lists.php

Earthbag Building posts examples of earthbag work around the world at www.earthbagbuilding.com.

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PHOTO CREDITS All photos and computer graphics are by Patti Stouter except these images which are used with permission:

Alternative Dorm in Haiti- Haiti Christian Development Project cover and page 52 2nd from top and page 56 bottom Turkish toilet- Magnus Manske (Mintguy) on Wikimedia Commons page 9 Arborloo graphic- SSWM, Sustainable Sanitation and Water Management page 9 PeePoo photo- Emmanuel Boutet (Supermanu) on Wikimedia Commons page 9 bottom Tippy tap illustration- Tippy tap.org page 11 top Graywater drain and cistern and fish pond- Sustainable Sanitary Alliance, pages 10 bottom, 11 middle, 13 Vetiver planting- Dr. Blofield (Treesftf) on Wikimedia Commons page 13 bottom Soil creep- Nigel Chadwick on Wikimedia Commons page 27 Salty soil- Commonwealth Science and Industry Research Organization (CSIRO) on Wikimedia Commons page 31 Peat fields- Hugh Venables on Wikimedia Commons page 32 top Sinkhole- Bryan Mackinnon on Wikimedia Commons page 32 bottom Liquefaction- Martin Luff on Wikimedia Commons page 35 Boukarou- Joseph Kennedy for Next Aid from www.earthbagbuilding.com page 36 top Screened corridor and curving wall- designed by Laurie Baker, photo by Seema K. K. page 36 middle and 59 left Rammed earth church- Dave (Pollinator) on Wikimedia Commons page 37 top Chehel Sotun Palace, Iran- Fabienkahn on Wikimedia Commons page 37 bottom Screen at Hamayun’s Tomb- Naik Pratik page 39 bottom right Ndebele house- Yanajin33 on Wikimedia Commons page 41 bottom Primary School- Francis Kere in Burkina Faso, photo by GandoIT on Wikimedia Commons pages 44, 60 top Indian cooking- P. C. Varte (Yann) on Wikimedia Commons page 45 Djenne mosque- from www.archnet.org/library/images. Page 48 right Earthen decoration- Hunnarshala Institute page 48 bottom and page 52 bottom right Ugandan thatch- Maleika2006 on Wikimedia Commons page 50 top Desi Training Center- Naquib Hossain on Wikimedia Commons page 50 bottom Patchwork construction- World Housing Encyclopedia page 51 middle Rice husk ceiling- greenhomebuilding.com page 53 top Seaweed roof- public domain on Wikimedia Commons page 53 bottom Damaged concrete- Alan Bowing page 54 top Yemen earth buildings- Jialiang Gao on Wikimedia Commons page 54 bottom Thai earth building- Owen Geiger page 55 top Haitian earthbag- Maria Benasa for Haiti Christian Development Project page 56 CEB hand press- Tdas13 on Wikimedia Commons page 60 bottom German rammed earth- Elias Grove on Wikimedia Commons page 61 bottom Cob technique- Fountains of Bryn Mawr on Wikimedia Commons page 62 Concrete post and beam- Paul Dubois page 62 middle and bottom Confined masonry photo and sketch- World Housing Encyclopedia page 63