Straw Bale Construction - what's old is new again

The use of straw as a form of insulation has been around for centuries. But it is now coming back into vogue as a sustainable, green and reliable means of insulating homes and other buildings.

Straw bales are readily available and provide cost-effective building materials, especially in areas where grains are grown. While additional precautions are required to build a straw-insulated house in regions prone to rain or humidity, there are many benefits to this type of construction. With an average insulation factor of R-35 or higher, straw-bale homes are ideal for locations where the heating, or cooling, of the home is an important consideration for comfortable living. In fact, the thicker the straw bale, the higher the R-factor. This type of insulation could decrease heating costs in homes by up to 75 percent. The 18-inch thickness of bales also provides significant noise reduction.

Straw bales are relatively easy to work with. Basic saws and other hand tools can be used to cut and/or shape walls and window openings. These bales can be sculpted to provide unique shapes within the home, such as window seats, or coved ceilings.

Another benefit to using straw bales for construction is the fire-resistance factor. During the building process, the condensed bales are coated with plaster or other substrates on both sides of the wall. If ignition does occur, the bales would smolder rather than burst in to flames, allowing residents to get out of the house safely until help arrives.

Keeping the bales dry is critical in building a straw-based home. If the bales are exposed to moisture content above 20 percent, the danger of fungal growth will arise and start the decomposition of the straw. However, if the bales are perfectly dry when construction begins, and stay that way, the walls can stay intact for centuries.

Optimizing your straw-bale home's insulation factor also includes the roof. Trusses must be placed close enough so the bales fit together tightly. Plastering - or otherwise coating - these roof bales is also important, not only for insulation but also for fire retardant measures.

One unique project in Washington State saw an organization provide funding for the construction of 11 straw-bale homes in an effort to offer housing for low- to middle-income residents. An additional benefit to the community occurred when a group of college students and young apprentices in the building trades were recruited to help the homeowners build their future homes.

A number of states have adopted straw-bale construction methods in their building codes. The government acceptance of this revised method of building has spurred some insurance companies and lenders to also give their stamp of approval, ultimately paving the way for more organizations to do the same.