Straw and clay
Build a sprayed Straw-Clay monolithic square, hex, or octagonal dome structures using inflatable forms and non-toxic, sustainable, local and recycled building materials.
Straw-clay slip is an ages-old wall infill technique that involves coating straw in a suspension of clay and packing it into temporary guide boards attached to timber framed walls. Originally used for post-and-beam houses, it is easily adaptable to modular inflatable form design. The straw provides insulation, while the clay holds the straw together and protects it from pests and the elements. Straw clay walls can be finished with plaster or adobe.
Best method is to spray Straw-Clay / lime slip into inflatable molds up to 18’ in several layers then remove mold and allow to dry. Spray stabilized adobe 4 – 6 in outer shell then Spray lime plaster inner outer structure. This will produce a super insulated extremely durable and secure structure that is very low maintenance, ecologically friendly, non-labor intensive, quick and ultra-low cost ! One of the chief advantages of building with straw and clay is that, in most places, locally harvested straw is easily available and clay can be dug at or near the building site. Thus, the embodied energy, or amount of energy used in producing and transporting the building materials, is minimal. Furthermore, the inflatable forms that are used to give shape to the walls during construction can be set up and taken down very quickly.
Straw-clay slip may be applied by hopper sprayer to increase speed and efficiency or it can be tossed on with pitchfork and lightly hand packed into place. Walls can also be reinforced with a bamboo “cage” for multi-story structures. Different mixes of straw, hemp or even coconut husk “coir” can be mixed with clay, lime, boric acid, natural latex, even fermented cactus pulp, depending on indigenous materials, to form a highly stabilized slip that is extremely durable, fire resistant, mold and pest free.