A house made out of straw. Can be plastered or stuccoed straw bales, or "wattle and daub" - a mixture of mud and straw built up on frames. These houses are very well insulated, making them quite efficient. Straw houses use less wood, in favour of a product that is often burned for disposal. Thus, they are ecologically sound.
Straw bales are not to be confused with hay bales, which are edible; straw is all cellulose, and has very little food value. Although they tend to be more labour intensive, they often cost less money to build. Straw bale houses meet the Uniform Building Code in many areas.