13. Straw Bale Building and the Foundation By Andrew Morrison Slab and Basement Foundations There are many different options for foundations. Concrete stem walls and footings, piers, monolithic concrete slabs, rubble trench with concrete bond beam, and sand bag and rip-rap stacks are all possibilities. In general, foundation systems contain one or more of the following: footings, piers, stem walls, and/or slabs.
The 2-foot thick walls of the Roble Road house soak up sunlight during the day and radiate heat at night. They provide at least 3 times the insulation value of a typical Bay Area home. Photo: DSA Architects / SF
These foundation walls are constructed with ICFs (Insulated Concrete Forms). They are the sensible, cost-effective alternative to standard walls of wood frame and cinder block. These forms pop out of the box as you see them here; you only have to fasten each section together in the configuration indicated by the blueprint, insert rebar, and fill the forms with concrete. The obvious advantage is that an ICF foundation can be built in a quarter of the time it takes to build a traditional wood…
"At the present time, the cost of labor to build a straw bale house is what drives the overall initial cost of new straw bale homes 20% higher than conventionally built homes." However if family, friends, or community can volunteer with bale stacking or plastering, costs can be dramatically reduced.