Earthbag Homes: Why they need a shield
Earthbag homes are created by stacking sacks filled with non-decomposing sand, clay or other native soils on top of each other until a wall is created. This technique has been used by the military for years to create strong, protective barriers or for flood control. These nearly bullet-proof walls can stand up to earthquakes, floods, storms and wind. The walls are also terrifically insulated and create thermal mass for solar heating.
Photo courtesy of Earthbag Building. This round earthbag home in Thailand is protected by native grasses and palms.
The bags are sometimes recycled feed or supply bags and they can be filled with native soils or lighter materials such as volcanic stone, perlite, vermiculite or rice hulls. The re-use of these items and the lack of the use of wood in this type of construction make it an environmentally friendly building option.
However, you’ve gotta protect those walls.
Earthbag walls, while they are strong and thick, are subject to decay from the sun’s rays and degradation from rain and water runoff. Many earthbag homes are also plastered on the outside with mud plaster or cement stucco. A strong roof with at least a two-foot overhang will protect earthbag walls for years.
Roofs for earthbag buildings can be built with many different types of construction materials including lumber rafters or trusses, timber beams, or bamboo rafters and trusses. One of the least expensive options is metal roofing since it can be made with minimal framing and recycled steel. For any roof you choose, earthbag walls must be anchored to the roof at their tops and using concrete bond beams on the tops of the walls with reinforcing bars is also recommended.
The Cozy Home Earthbag Shield
Cozy Home Plans sells an Earthbag Shield steel roof system that completely covers and protects an earthbag home. The Shield also comes with a kit that includes new polypropylene bags, barbed wire which is used for the “mortar” in-between the rows of bags and 20 1/2″ rebar stakes in 20 foot lengths for stability. A Shield (and the kit) for a 24 x 30 foot earthbag house costs $3,897, a 24×40 foot Shield and kit costs $4,497, and a 24 x 50 foot Shield and kit costs $4,997. Prices include delivery up to 250 miles from zip code 75201. The kits weigh about 3,000-4,000 pounds and several people will be needed to move the trusses.
Photo courtesy of Earthbag Building. This earthbag home in Haiti, named the “Sun House”, was built to house children needing help from the local church. The bags were poly bags that previously held rice, barley and wheat. The soil inside the bags was moistened sand and clay. Barbed wire was used as mortar between each row.