The Disney movie Bambi scarred me for life, but an earlier story from Uncle Walt did almost as much damage. The Three Little Pigs was the tale of two foolish porkers that built new homes; one from sticks and one from straw, and of course saw them blown to smithereens by one strong gust of wolf.
Well, who knew? Pig Number Two wasn’t so dumb after all. He was merely forward thinking, eco-friendly and seriously lacking in good engineering skills.
There are some green building techniques and materials out there that really are a bit on the fringe and building a home from straw is one. But this type of construction is gaining in popularity in spite of serious obstacles that have nothing to do with the soundness of construction or the wisdom of the technique.
As I recall from the movie, the pig’s house looked like a haystack (the first pig’s house of sticks resembled an unlit bonfire) and that isn’t at all the profile of a real straw house.
Straw bale construction utilizes the waste that remains in the field after the harvest of oats, barley, wheat, rice, and other grains. Unlike hay, it has no nutrient value as livestock fodder and typically farmers don’t want to plow it under either. Some of it is used as animal bedding or landscape material but much of it ends up being burned, contributing to air pollution. However, when machine baled straw makes a very green building block for constructing homes, barns, churches; virtually any building that could be built from bricks or two by fours. This is not some crazy new phenomenon, straw bales were used on the American plains in the 1800s and some of the buildings are still standing.
Today there are 634 homes in the United States listed on the International Straw Bale Registry (this may represent only a fraction of the total.) California, Texas, Colorado, and Arizona have about half of the total. Skipping through the list we found two bedroom homes of around 1,000 square feet and half-million dollar 3,700 square foot residences with cathedral ceilings and radiant heating.
The technique for building with straw bales is simple. The bales are stacked in offset courses like brick, either flat or on edge and mortared together or more often secured with rebar, or wood or bamboo stakes. Once the bales are in place they are covered with chicken wire or metal lathe and covered with concrete stucco. Roofs, windows and doors are framed as in traditional construction.
The final appearance of a straw and mortar house is similar to that of adobe or rammed earth houses in the Southwest.
A more traditional appearance can be achieved by using straw bales as infill in timber frame construction. This, however, does not have all the cost and environmental advantages of bales and mortar.
These advantages are many. First, a straw bale house can be a do-it-yourself project and a low-skilled one at that. Little heavy equipment is needed other than for lifting the bales which weigh between 50 and 100 pounds. Material costs are very low although the cost of the bales can vary during the year and transportation costs have to be factored in. The bales insulate to an R factor of 30 to 45, are highly fire resistant when combined with mortar and do not appeal in the least to termites.
Best of all, this type of construction uses totally sustainable material that would otherwise contribute to environmental problems.
So what could be the problem with straw bale construction? There are several, all institutional in nature and related to the novelty of the method.
Local building departments have no idea what to do when confronted with a straw bale building. Builders (who are nearly always the potential owners) have to be prepared to supply references from other towns with experience with such buildings who can offer guidance.
Many owners find that, once built, the homes cannot be insured. The ad hoc nature of the building codes is one problem and we can just imagine the reaction of some insurance agents to learning of the underlying materials; “Your house is built of what?”
And if you can’t insure a house you probably can’t get a mortgage. A few major banks, notably Wells Fargo, have written straw bale house loans but most owners seem to finance through private lenders, out of pocket, or through small-town banks and credit unions.
But acceptance is growing. Only five states do not have at least one house listed by the Straw Bale Registry Project and there are grassroots efforts to educate local code enforcement, insurance companies, and banks on the advantages of the construction.
If you are curious about straw bale houses check those on the registry (www.sbregistry.greenbuilder.com). Many are open to visitors by appointment.