Letter Re: EcoBeam Construction for Ballistic Protection

Mr. Rawles,
I recently stumbled upon a magazine article highlighting a new home construction technique for people living in some of the most impoverished lands of Africa. It’s called EcoBeam.
The system uses very little lumber or concrete and gains most of it’s structural support from sandbags. Since the walls are essentially stacks of sand bags it has great mass (read: it will hold up in adverse weather conditions – doesn’t require a foundation) and has anti-ballistic properties. Since the bulk of the structure is sand and sand bags little if any heavy equipment is needed to build it . In fact, no power tools would even be required as evidenced by the test structures being built in Africa right now. See this site: EcoBuildTechnologies.com
Vertical i-beams made of wood and a metal zigzag web in middle are used to “stick build” the frame using what looks like approximately 36-to-48″ centers (or what looks like 2 , 3, or 4 sandbag [width]s.) Sand bags are filled and stacked in the space between the beams. The whole assembly is then covered with a mesh or expanded metal mesh and plastered. North Americans, having far more lumber resources, could probably substitute this wood/metal I-beam for some pre-fabbed plywood I-beams commonly used as floor joists in modern home construction.
This might make for a great construction technique for building retreats in remote or low access regions or as a method of construction for support structures like observation/listening posts, etc. I could envision the integration of indigenous stone, soil, brush, etc. on the plaster coating to aid in camouflaging the structure. The other great benefit to the system is it’s thermal properties. It retains heat and cold quite well.

I hope this serves as some benefit to the community. Thanks for bringing us all together. – Tanker

JWR Replies : For many years I’ve been a fan of Earthship construction, (compressed soil-filled tires) which has many of the same attributes a the new EcoBeam method. Sand and and gravel are better at stopping small arms fire than even reinforced concrete. This is because they shift and refill voids after they are created by bullet strikes. From a practical standpoint nothing stops bullets better!

Keep in mind one important proviso: Beware of any unreinforced construction method, especially in earthquake country. You will recall from news stories about earthquakes in many Asian countries that they have high death tolls. This is often because in many impoverished countries metal reinforcement (“re-bar”) is omitted, to reduce construction costs. In an earthquake, such buildings just collapse. Sandbag construction and Earthships must be reinforced. This is best accomplished by placing re-bar vertically on two-foot (or narrower) centers through the wall stacks, making sure that the top of each piece of re-bar passes through a wood top sill, or that it is at least firmly wired in place.