Strawbale Homes

     Although it may sound like something out of the childhood tale, “The three little pigs”, straw bales are effective natural materials in homes. Over a hundred years ago, people used bales of straw to build their homes. They found that these bales of straw kept the homes warm and well insulated. Once again, home designers are adopting this design to naturally and passively keep homes warm without the use of conventional energy.

     Building with bales of straw has become very popular in some parts of the country, especially in the Southwestern United States. Many localities in famous parts of New Mexico and Arizona have specific codes for straw bale construction, and some banks are willing to lend on this technique. Straw is a renewable resource that acts as excellent insulation and is fairly easy to build with. Care must be taken to assure that the straw is kept dry, or it will eventually rot. For this reason it is generally best to allow a straw bale wall to remain breathable; any moisture barrier will invite condensation to collect and undermine the structure. Other possible concerns with straw bale walls are infestation of rodents or insects, so the skin on the straw should resist these critters. Make sure the climate and ecology of the area can help support a straw home so that these don’t become an issue.

     There are two major categories of straw bale buildings: load-bearing and non-load bearing. A post and beam framework that supports the basic structure of the building, with the bales of straw used as infill, is the most common non-load bearing approach. This is also the only way that many building authorities will allow. While there are many load-bearing straw bale buildings that are standing just fine, care must be taken to consider the possible settling of the straw bales as the weight of the roof, etc. compresses them.

     Erecting bale walls can go amazingly quickly, and does not take a lot of skill, but the rest of the building is similar to any other wood frame construction. In fact, straw bale houses typically only save about 15% of the wood used in a conventionally framed house. The cost of finishing a straw bale house can often exceed that of standard construction, because of the specialized work that goes into plastering both sides of the walls. The result is often worth it though, because of the superior insulation and wall depth that is achieved.

     Straw bales are structurally sound. They are able to withstand an earthquake much better than some popular building materials. Being somewhat squishy, they work much like a shock absorber rather than being rigid and breaking. Just like wood framing there has to be a balance between strength and flexibility. Recently a straw bale cabin was put to the test on a shake table to get an idea of just how it would perform in an earthquake. It survived a simulated earthquake, passing the test with flying colors.

     If you plan to build a house and live in an earthquake prone area you might consider building it with straw bales. If the climate can sustain straw bales, it would be an excellent choice for a building material.