The current newsletter from CalEarth describes how they have been designing an earthbag shelter/home prototype for use in Haiti. This structure, consisting of a 10 ft. main dome surrounded by 3 apses (a 7 ft. sleeping apse, a 5 ft. fire cooking apse with storage below, and a 5 ft. apse that can be used for storage or as a sleeping area for small children) was designed to house six people comfortably.
From laying the footprint to applying the plaster, a crew of 9 people worked a total of 15 days to create this prototype. The cost of this structure, including earthbag tubing, barbed wire, cement, waterproofing materials, basic building tools, windows, and a door with a lock, came to under $3,000. According to the newsletter, “Although the cost may seem high, it is important to note that we made it a point to create a permanent shelter thus stabilizing with cement. After visiting Haiti and meeting with government officials, it became very apparent that for those families living in the tent camps, any relocation would be permanent, even if stated otherwise. So we built this structure with that in mind, and included all the amenities needed to live in this shelter for a long period of time. If we were to design a temporary emergency shelter, the costs would be significantly lower.”
How this dome will be waterproofed is still unknown. They are planning to experiment with using an elastomeric roofing compound. They have already tried using tar compounds, but are hoping that an elastomeric paint may be the simplest way of creating a reliable and serviceable waterproof membrane.
You can read their entire newsletter that describes all of this more fully on their website.