Straw bale houses have enormously good insulation values, and can be built with relative ease and speed. They may be load-bearing, but more often they incorporate a post-and-beam frame. The bales are finished with a coat of plaster – often earth or lime based.
The design issues are similar to earth buildings, but the need to avoid moisture and weathering is even more crucial. The bales must be dry before installation and remain dry throughout their life, as once wet they are more likely to compost than dry out. The construction detailing and plaster coatings make or break straw bale construction.
Straw bale houses were developed in America and are rising in popularity. Those wanting to build a straw bale house would need to engage an experienced designer, and do the analysis to apply for a building permit as an “Alternative Solution” under the Building Code.
Architect and EBANZ member Min Hall’s Master of Architecture thesis:
“Earth and Straw Bale: An investigation of their performance and potential as building materials in New Zealand”