Those in straw houses

Owners of Austin-area homes built with bales of straw and other natural materials like the idea that they are having less of an impact on the environment, and they're getting health and economic benefits as well.

The bales for the 18-inch walls have been covered with stucco on the home's exterior and smooth adobe plaster on the interior, helping to keep the home earthy, comfortable and quiet. His average monthly utility bill is about $55. And the large, deep window sills are perfect for his two kids to sit and read their favorite books.

In addition to straw bales, green builders also are using rammed earth, or dirt compressed into building blocks; cob, a mixture of adobe and straw; and aerated concrete blocks.

The building project started last fall, with carpenters erecting the post-and-beam structure that would support the weight of the roof. Then on a sunny November day, people came to the Rainey's bale-raising party from as far away as Houston and Oklahoma. News of straw-bale raising workshops is spread through word-of-mouth and Internet message boards.

For six hours, everyone worked to raise the walls, using more than 300 bales of straw. Some stacked the bales, some droves stakes through the bales to anchor them together. Others tied bamboo stakes together on both sides of the bale wall, giving it stability until plastering.

Rainey estimates it will take three more months for contractors to finish the electrical wiring and plumbing. Then the Raineys will hold another workshop, led by a local contractor, this time covering the topic of plastering interior walls. Before the walls are plastered, Rainey must trim the edges of the straw bales to ensure a smooth wall surface. Small recesses will be cut into the walls for niches, and wood studs will be added in preplanned areas in order to have wall support to hang pictures.

So far, the biggest surprise in the building project was related to insurance coverage. In short, his insurer told him it wouldn't cover a straw-bale structure. But Rainey said he talked with other people in town who know about sustainable building and found a carrier who covered such homes.

Obregon said that many people wrongly think that straw bales are highly flammable, and that this leads some insurers to refuse coverage. But Obregon said that structural engineers have tested straw for fire safety and discovered that when properly installed, these structures do not burn easily.

"The heat transfer is not an issue. It's great," Obregon said. In fact, densely packed bales limit oxygen flow.

"The biggest concern for our area can be the moisture level in straw bales," he said. It's important to keep the bales moisture-free, especially before the wall-raising, he said. It's also important to waterproof the exterior walls, to create wide roof overhangs and to seal the doors and windows tightly.

Vicki Howard of Austin chose an alternative to straw-bale construction. She decided that living in a house built of dirt would be a clean, although counterintuitive, solution to her health problems. So she lives in what's called a rammed-earth home.

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