Willows builder harvests success using rice straw

Two of the large buildings Benchmark constructed for the Desert Living Center were built of rammed earth, a process taking quarter-inch particles of rock from a gravel pit, and mixing it with a small amount of dry cement and enough water to where it will hold together when it's packed. Green said he has also added beach sand to the mix on a project on the coast.

The mixture is then dumped into wooden construction frames, similar to concrete forms only stronger, and pounded into short layers. Benchmark developed special equipment for the process.
Green said he can do a lot with rammed earth because of the colors of various materials. The final effect is that it looks like concrete, only it's slightly rougher and contains wavy, multicolored patterns after it has dried.

One of the challenges Green faced was transplanting all his equipment and crews to Las Vegas, along with the truckloads of straw bales. Working with large pieces of equipment and with more than 100 subcontractors in the area at once also meant he had to spend a lot of time scheduling and planning ahead.

Building with straw bales or rammed earth is more expensive, Green said. Rammed earth takes roughly four times as much labor to build with as concrete does, he added. Straw bale buildings are also more time consuming and expensive to build with than a normal stick-frame house because the framework also has to be built. More materials and time are also used to cover the straw bales with plaster or stucco, inside and outside.

Straw bales have an advantage in that they are self insulating. Green said most bales are rated at R-54, though it performs considerably beyond that. It also cools so well that at the Desert Living Center, air conditioners aren't needed, he said.

He also said it's fire safe once its built, especially after it has been covered with stucco or plaster on each side. He compares it to trying to burn a phone book all at once. It isn't easy to ignite because the bales are so compacted, and fire can't get much oxygen. A typical bale is 75 pounds of tightly compacted straw.

To illustrate how tough it is to burn a straw bale structure, he told of a police building in Visalia he built that someone attempted to burn down by pouring gasoline on it. Green said they tried three times, and either the fire went out or it didn't burn enough to cause much damage.

He said the only time he has heard of a straw bale structure burning was a home in an area that was caught in a fire storm. The fire in that case was so hot, houses exploded from the inside, out.

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