ABOUT ALTERNATIVE WALLS

Straw-bale walls perform very well

Of the many alternatives to conventional wood or masonry walls, straw-bale construction has gained the most adherents in the U.S. Other methods mentioned below also have their supporters, but most are regional or used by few people.

Tight and warm

Because most straw-bale walls are plastered on both sides, they have very little air infiltration. As with all building types, junctions of dissimilar materials — particularly around windows and doors — are weak spots for air infiltration and can do much to undermine an otherwise high-performing wall system.

Straw-bale walls also resist heat flow, though just how much is still an area of contention. The results of laboratory thermal tests on straw-bale wall systems have varied widely. After studying existing data and funding its own tests, the California Energy Commission adopted a nominal R-value of 33 for plastered straw-bale wall systems. Although some enthusiasts cite a much higher R-value, R-33 still represents a significant improvement over most standard residential walls.

Straw-bale walls are susceptible to mold and rot if they get wet, so these homes should have wide roof overhangs, a good height above grade, and appropriate weather detailing. Rain-screen cladding may be an appropriate solution.

There are straw-bale structures in every American state. The oldest were built around 1900. The technique is supported by legislated guidelines or acceptance mandates in California, New Mexico, Nevada, and Oregon, and code adoption in several municipalities in those states, as well as in Texas, Colorado, Arizona, and Nebraska. For more information, see Straw-Bale Walls.