Roofs present a number of challenges, including how to provide adequate, affordable insulation so the home remains comfortable. Straw/clay, also called straw slip clay is one low tech, low cost solution. The basic process involves making thin slurry of clay and water and then mixing this with straw.
The following information is quoted from An Insulation for San Pablo.
“Our goal is to create a new roofing system that will provide better insulation properties than that of corrugated steel. This material should be:
• easy to construct
• fabricated from local materials
• supportive of the local economy
• environmentally friendly
Our Proposed Solution
We suggest that San Pablo improve the insulation of its houses by infilling its roofing system with slip straw. The slip straw would be stuffed between roof framing members, underneath the existing corrugated metal roof. Chicken Slip straw, is a natural building material that is made of loose straw coated minimally in clay slip, which is clay diluted with water to the consistency of a milkshake. Slip-straw is used as an infill panel built between framing members; it is tamped by hand or with a stick between “slip forms” and finished with plaster, which would act as a fire and moisture barrier.
Environmental and Cost-Benefit Analysis
As there is no environmental impact from our current insulation method, we compared the carbon footprint of the production of different insulation methods, including western methods, which include fiberglass insulation. There is no carbon footprint generated by using our insulation system.”