Hesperian Health Guides
Building a Healthy Home
Homes designed with care contribute to communities that are safe and healthy. Putting a house in a place that takes advantage of sun and shade can help with heating, cooling, lighting, and ventilation. Choosing building materials right for your climate is also important.
Make best use of sunlight
When building a house or a settlement, consider where the sun will be at different times of the year in order to make best use of the sun’s heat. In hot months, the sun rises high overhead at noon and provides direct heat for much of the day. In colder months, the sun is lower in the sky, gives little heat, and travels a different path through the sky.
In southern countries, houses will be more comfortable if most windows and exposed walls face north, where the sun is. In northern countries, most windows and exposed walls should face south. This general rule will help the entire house capture and retain the sun’s heat.
|In the cold season, the low sun shining on exposed walls and windows helps keep a house warm.||In the hot season, trees planted on the side of the house where afternoon sun shines will help keep the house cool.|
Choose materials for warmth
In places that get cold, some building materials help capture and store heat in the house. Materials with more thickness store heat best. Stone, brick, and blocks made of mud and straw store heat better than wood or unfilled concrete blocks. Filling concrete blocks with earth or concrete helps them store heat better. Using any of these materials, the best wall thickness for storing heat is 4 to 5 inches.
|When the sun shines on the house, heat collects in the walls and floor.||When the sun sets and the air cools, the walls and floor release heat into the room.|
Protect against heat and cold
(to prevent termites from eating it).
|Sealing cracks in the walls makes a big difference in keeping cold out and heat in.|
If you cannot build double walls, cover inside walls with paper, foam, cardboard, or similar materials. This will add some insulation.
Thatch roofs give good insulation. So do floors of brick and compacted earth. To keep heat in or out of the house, seal cracks or holes around windows and doors. Cover windows to help keep the home cooler during the day and to retain heat at night. Windows that open will also allow air to flow for good ventilation.
Choosing building materials
The materials used to build a house can make the difference between an uncomfortable shelter and a healthy, beautiful one. But when forests and watersheds are damaged, natural building resources such as wood, thatch, and other plant materials are lost. And when large amounts of concrete and other “modern” materials become available, traditional materials and knowledge of how to build with them is lost, or is no longer valued by many people. The best building materials:
- come from the earth, and can be reused or returned to the earth when the life of the building is over.
- are harvested and produced locally, and fit the local climate.
- do not contain harmful chemicals or require large amounts of energy to produce.
Teenagers produce improved building materials
In the neighborhood of Santo Antonio on the outskirts of Brasilia, the capital of Brazil, most houses are built in a few days using clay bricks and concrete blocks that are bought outside the community. There are few skilled builders and no one has much money, so residents build their houses with the help of unskilled workers.
Because of this, materials are often poorly prepared, by adding too much water to make cement, or by leaving out reinforcing steel.
Rosa Fernandez, an architect, visited Santo Antonio and saw how the lack of skills led to poor planning and building. She set out to improve the situation. With the help of government funding, she trained a group of teenagers in Santo Antonio to make compressed earth blocks. These were made from 2 parts sand to 1 part clay, with a small amount of cement, and then were pressed in a simple hand-operated machine. After the teenagers had learned to make the blocks, Rosa taught others in the community how to build with them, and the teenagers began a business of making and selling the blocks.
Now, many new houses are built with this safer, stronger building material. The money people use to buy the blocks stays in the community and helps to build a stronger future. And with all the practice and training the teenagers received, Santo Antonio now has many skilled builders.
Traditional and modern building materials
Most traditional buildings use combinations of mud, sand, clay, stone, straw, wood, and plant materials such as bamboo, thatch, and vines for roofs and walls. These materials are strong, locally available, and cost little or nothing. But they also have some problems. Mud walls may erode in the rain, thatch roofs can become homes for insect pests, and buildings that use only these materials may not last long.
Factory-made materials such as concrete blocks and metal roofing have replaced traditional materials in many places. People often use concrete because it is easy to handle and a house can be built in stages, with additions built on as the family earns more money. For some people, building a concrete home means economic success and a modern lifestyle.
But houses built with factory-made materials may not be best for peoples’ health or the environment. Often they are not well insulated for cold weather. Making concrete requires a lot of water and a lot of energy. If they are not reinforced, concrete block buildings collapse easily in earthquakes. Also, these materials are costly, and often are only available to people in large towns and cities.
When planning to build a home, consider the good and bad qualities of different materials that may be available. Just because others build their homes in a certain way does not mean it is the best way for everyone.
How to make natural earth plaster
- Add sand and clay soil to water. Let it sit until clay and sand absorb the water.
- Mix by hand until there are no lumps.
- Add chopped straw and mix again until there are no lumps.
If you are plastering a mud wall, wet the wall. For adobe, straw bale, or other surfaces you may need to apply a layer of clay before applying the plaster. Apply plaster to a small section of wall with your hands and then smooth it with a trowel. When it dries, test it. Does it crack easily or crumble when you press it with your thumb? Does it break away from the wall easily when you pull it, or break down easily when you sprinkle water on it? If it cracks, add more straw. If it crumbles, try adding a paste made from wheat flour and water. If it breaks down easily in water, add longer straw. Once you have plaster that does not crumble, crack, or break down easily, apply it to your walls.
To plaster a floor, add more sand to this mix. Press down the surface to make it smooth and level before you start the new floor. Then apply plaster, smooth it, and let it dry for several weeks to prevent cracking later. If possible, seal the floor with linseed oil after it dries.
Earthquake resistant building
Many lives are lost every year because people live in houses that do not withstand earthquakes. Houses of unreinforced concrete block, or unreinforced brick or earth, and houses without solid foundations, are most vulnerable to earthquakes. Houses made of traditional and flexible materials, such as mud and sticks, wood, or piled earth mixed with straw (called “cob”), or straw bales stacked and tied together and covered with plaster (see Other Environmental Health Resources) are better able to withstand damage from earthquakes.
Combining traditional materials with improved building methods, such as foundations, cross-braces, and waterproof plaster, can make houses safer, more comfortable, and affordable. To reduce the risk of earthquake damage to earthen houses:
- Build low, single story, small buildings.
- Make walls curved if possible, especially at the corners.
- If you build in a square shape, reinforce corners with wooden cross-braces. If wood is not available, you can use wire.
- Build a foundation on solid ground using lime mortar or concrete with broken brick or large stones. Anchor the foundation materials together by including sticks, bamboo, iron wire or metal rods in the mix.
- Secure the wall to the foundation using rush matting, sticks, nails, metal, or iron wire cemented into the foundation.
- Use light materials for the roof (thatch or corrugated metal).
- To make brick or block houses safer, fasten the layers of brick or blocks together. Attach crossbeams from one wall to the other, and set horizontal braces between the beams to prevent the building from moving side-to-side. Attach the roof to the crossbeams.
|Light materials, like straw bales, make walls that are safer in earthquakes, and help keep inside temperatures mild.|