earthship

Building with Steel Reinforced Rubber Encased Earth Bricks

January 8th, 2012

There are a number of building projects at TSH which I have recently decided to tackle. Both of the projects I want to work on, a retaining wall and a cool storage cellar, are underground structures which will be in constant contact with the earth, and which will be subjected to considerable loads. I have been trying to work out the best building material to use for these applications and recently I think I have cracked it… Steel Reinforced Rubber Encased Earth Bricks otherwise known as used car tyres!

The use of car tyres as a building medium has been popularised by Michael Reynolds, the founder of earthship biotecture. Mike has used the tyres to create a new type of building known as Earthships (Earthships on Wikipedia); so named for their ability to form an almost completely self-contained human ecosystem. Earthships have active rainwater, greywater and black water collection/treatment systems, generate their own energy (though photovoltaics and wind generation), and are exceedingly well insulated due to the nature of their construction. And it is this final point that offers so much potential for the construction projects at TSH.

The major project that I am undertakng is building a cool storage room which will be underground for most of it’s wall height. This cellar needs to built strong, so as to withstand the weight of the soil pressing against it, and be well insulated. I think that the tyres meet both these requirements beautifully. In addition I think it is a great example of re-use rather then recycling. IE, the tyres re a waste resource that can be ground up and melted down to create all sorts of other products, however doing so requires addition of energy… lots of energy. But using the tyres for building like this doesn’t change them in any form and the only energy used is the human energy of packing them. I think I might be carrying sufficient energy for the task…

Basically the process is that the tyres are placed in-situ, and then filled with soil removed from the cut-out (spoil). This soil is then compacted into the tyre using a mallet and elbow grease. Finally another row of tyres is added in a stretcher bond format. There is no need for any reinforcing rods though when using then as a retaining wall a batter is definitely recommended. I’m using approx a 15-1 batter on this project which means for every 15 rows of tyres (in the vertical dimension) I am sloping them back into the soil by 1 width. Given the tyres very wide footprint I believe that this will be adequate.

It’s not exactly skilled work though it is physically demanding.

Below are a few photos of the beginning of the project, with more to come as the building progresses.