Face Your Risks
Learn About Techniques
Many owners and builders don't know whether their land is in a high or low risk area. Find out! Wise builders save lives and prevent damage when they know what to plan for.
- Earthquake- The gshap (Global Seismic Hazard Assessment Program) maps cover the world. Red is high risk, green is low risk. Get more detailed information from university geology departments, earthquake engineering organizations or local governments- but find out!
- Strong winds- Small violent tornadoes happen in continental plains, larger hurricanes impact coastal areas, and high wind gusts occur in mountaintops and steep valleys. Ask or google about it.
- Floods- Sudden winter thaws, heavy rains, high storm tides and surges, or with tsunamis strike low-lying areas near rivers, lakes, or coastlines. Ask for maps of flood risk. Any land within a mile of the ocean and less than 25' higher than sea level is at risk of a tsunami.
- Landslides- Sites downhill from steep slopes of gravelly or heavy clay soil can be in danger if trees above are removed or more water is retained into the hillside (irrigation/ blocked gully).
- Fire- Wildfire is a risk that occurs periodically in dry regions. Be ready for it.
- Problem soils- Sticky clays break buildings, sands near mountains may settle. Find out more.
Use local, inexpensive materials that fit your climate and resist your local risks. Safe single story houses can be built cheaply of these materials:
Heavy earthen walls resist strong winds, fire, and are not damaged by insects or mold. They are comfortable in hot, humid and hot, dry regions. With careful designs and reinforcement earth walls can resist earthquakes. Thick walls may support a light wall second story. Reinforced earth site walls may even help to deflect landslides.
Earthen walls stabilized with cement or lime, or earthbag walls filled with gravel and sand can resist flood damage. In specially designed buildings they may even be able to survive some tsunami forces.
To understand why earth works so well for building: Why Build with Earth?
Lighter natural fiber walls are easier to reinforce for earthquakes and help retain heat in climates that have cool or cold nights. If reinforced and tied carefully to a heavy base they can resist strong winds. Lighter walls may survive problem soil locations better than heavy walls. Combined with breathable earth or lime plasters, they resist damage by mold.
Light plastic trash walls with cement stucco resist earthquakes well and may not be damaged by prolonged soaking in floods. They will not be damaged by insects.
Solid earthen walls usually require a lot of heavy labor. In the developing world they are very cost-effective when suitable soils are available on the building site. In frost-free areas they can receive cement stucco:
Earthbag- this reinforced geotextile technique includes both tube and bag construction of 15" (38 cm) thick wallsNatural fiber walls add some insulation value and/or some thermal mass when soaked with clay slip or plastered with earth. In damp climates they should be located above the rain splash height on a base wall of earthbag 12" (30 cm) thick or CEBs.
Rammed Earth- 18- 24" (45- 60 cm) thick walls
Compressed Earth Block (CEB)- 6- 12" (15- 30 cm) thick walls
Tire Walls/ Earthships- 24- 30" (60- 80 cm) thick walls
Reinforcing earth blocks- CEB or any adobe must be reinforced in quake risk areas. Mesh and plaster works, or small concrete columns can be poured after the blocks are built for confined masonry.
Some of these techniques are common as infill in wooden frames in areas with heavy snow loads. In frost free areas they can hold up the roof without a frame when used for small homes:
Natural mesh tube walls- 6 to 8" (15- 20 cm) thick plastic mesh tubes sewn and plasteredRecycled plastic trash walls can turn a problem into a resource, and work well with cement stucco.
Light straw or chip clay- 8 to 10" (20- 25 cm) thick packed into wooden forms
Ubuntu agricultural blocks- 8" (20 cm) thick of roots/straw/stems compressed and baled in a hand press
Ubuntu trash blocks- 8" (20 cm) thick foam, film, or recyclable plastics compressed in a hand press and post-tensioned with wire between vertical rebars. Structural and proven to survive quakes.
Structural trash walls- 12" (30 cm) thick recyclable plastics filled with sand and tied together. These are labor intensive.
Recycled mesh tube walls- 6" to 8" (15- 20 cm) thick plastic mesh tubes fill with hand-compressed plastic foam, film, or bottles
Recycled foam roof vaults- When mesh tubes are filled with lightweight plastics they can form a 3 m wide vault with no rebar support for regions without snow. Cement stucco exterior and clay plaster interior help to stiffen the structure.
Infill bottle walls- 4" (10 cm) thick layers of bottles filled with film plastics layered between chicken wire in a wood or concrete structural frame
Information about weather-resistant wall finishes for natural materials:Cement stucco works well on trash wattle or Ubuntu trash blocks. A strong layer of stucco on a fishnet mesh works well on earthen walls in frost-free regions. But walls of natural fibers and clay are not compatible with stucco.
Lime plaster- This historic exterior wall material is simple to use, has a low carbon footprint, and is easy to maintain and repair.
Earthen plaster- All-natural plasters can be bought in many beautiful colors. If local builders have access to some light color and non-dusty clay soil, this is the cheapest way to finish interior walls.