The building structure is made of walls of packed tires laid out on a 25’ x 30’ footprint. The interior space enclosed by the tire walls measures 410 sq ft. The tire walls are 9’ high and follow curved patterns creating a geometrically stable shape where no buttressing is needed. In addition, the lack of sharp corners helps in the event of an earthquake, as stresses would accumulate there and thus create weak spots in the structure. Additionally, some of these tire walls retain the earth located at the North side of the building.

Tires are filled with the earth taken out during the excavation stage, and non-biodegradable waste. The tires are stacked in a running-bond pattern to maximize interlocking between courses. Additionally, horizontal rebars are laid between two courses about halfway up the wall in order to stiffen it against lateral forces during the construction stage. A 8” deep concrete bond beam is poured on top of the last course of tires in order to tie the whole structure together.

Walls are founded on trenches filled with tamped down gravel and the courses of tires located below the finished floor level are filled with gravel. This foundation provides a solid footing for the walls while preventing any water infiltration via capillary action. Similarly, the ground floor slab is made of concrete poured on top of a 4” thick layer of gravel in order to avoid any contact between the concrete and ground water.

The roof slab is a 5” thick concrete slab supported by a concrete beam framing tying into the bond beam and concrete columns. This slab can be used for the creation of an additional level as long as most of the structure above sits on top of the surrounding tire walls.

The door openings in the tire walls follow the geometrically-stable arch shape to avoid the presence of lintels. The arch is created through the use of earth bags.

Wall finishes (interior and exterior) are made of cob (earth + sand + straw) applied against the tire walls where nails have been added to enhance the cob adherence. The cob fills the voids between tires and creates a flat surface. On the inside, it is covered by two layers of plaster: a form coat (cement + lime + coarse sand) and a final coat (cement + lime + fine sharp sand).