Homes made of straw drawing new interest for environmental, energy benefits.

When Mike Evans and his colleagues at the Tree of Life Nursery near San Juan Capistrano, Calif., began constructing some of their buildings in straw more than 10 years ago, they had good reasons: The buildings would be environmentally friendly, using straw bales, a recyclable and organic product.

They would have excellent insulation. Straw bales provide a very high insulation rating of R-34 to R-50. That's roughly three times the insulation rating of most homes with conventional fiberglass batting in the walls. They would be relatively inexpensive and easy to build.

And straw bales would fit in well with the natural flavor of their business, which specializes in native California plants.
The number of people building homes out of straw is rising, with an estimated 500 to 600 such homes in California alone, and interest is growing nationwide for good reasons.

"The higher prices of energy and building materials are making this kind of construction much more appealing to everyone," said Maurice Bennett, who runs the California Straw Bale Association, a nonprofit trade group headquartered in Angels Camp, Calif.
"We've had a great deal more interest everywhere - even in Southern California - in building with straw bales," said Bennett's wife, Joy, who runs the group jointly with him.

Straw-bale construction of homes and other buildings has never taken hold in mainstream home construction. However, with construction-material prices starting to accelerate and the materials alone getting more difficult to obtain, more people are taking another look at straw bale.

The trouble is, most urban and heavily populated suburban areas that come under city government control have code requirements that straw-bale homes cannot meet. Most straw-bale homes and other buildings are in rural or semi-rural areas or are under county government control, which tend to be much more lenient on such alternative building techniques.

The Tree of Life Nursery, for instance, is several miles east of populated areas of San Juan Capistrano. So they didn't need special permission to build their five buildings with bales.

Building with straw bales isn't a new construction technique. What the Tree of Life Nursery people did was to continue a tradition that goes back a couple of centuries.

Essentially it's a simple method of stacking bales of straw, usually in what's called a "running brick" pattern - two end-to-end and one centered on top and straddling each half of those below. A layer of "earth plaster" is spread over the inside and outside of the bales so that the finished product looks like a stuccoed wall.

Typically, when people interested in straw-bale construction ask building firms and others about it, one of the questions they have is "Doesn't the straw make it easy for a fire to burn the house quickly?" The answer is an emphatic no. The straw bales are so tightly packed that there is very little room for oxygen. Straw bales will burn, but it takes awhile to get them going and continue burning.

What do you put on the interior and exterior walls of a straw-bale building? Whatever you use, say the experts, it should be a substance that "breathes." Earth plaster - a simple type of masonry - is often used. Plaster has a lower moisture content than straw so it tends to draw moisture from the straw bales.

It is possible to use something like wood siding on the exterior, but it should be "gas permeable" - basically, it should be able to allow air to pass through. That's one benefit many straw-bale homeowners say they like, the ability of outside air to slowly permeate the walls, especially if there is a plaster overlay.

Regular paint can be used on the walls. Much of the rest of the construction process is standard. You'd think such a building process would be much cheaper than conventional building construction. It can be if you do most of the work yourself, but it can also be somewhat labor-intensive. The cost of building and finishing the exterior walls of a straw-bale building might run as much as 15 percent more than conventional walls. However, balance that initial cost against the long-term costs of heating your home and you'll be way ahead with straw bale.

Want to finance your straw-bale home? It is best to get financing through the straw-bale builder. Either the builder will finance you directly or have arrangements through a lender of their own. Thinking about doing it yourself? Expect some heavy lifting, and a lot of it.

The bales come in many shapes and sizes, but a medium-size bale might be about 23 inches by 16 inches by 42 inches. It could weigh from 75 to 85 pounds.

The length of time it takes to construct a straw-bale building depends on the size and complexity of the building and how much help you have. If you do it yourself, with just a few friends to help, plan on it taking several months to a year. It is not unusual, though, for the straw-bale walls to be constructed on some homes in a day.

You can also pay a firm that specializes in straw-bale construction to do it for you. Again, prices depend on the size and complexity. The first of the Tree of Life straw-bale buildings was erected in 1993. "It really wasn't that difficult," Evans remembers. "We got some advice from a guy in San Diego who was connected to some people in Tucson who had the expertise."

Though Evans and his fellow nursery workers did much of the work themselves, they also had help from carpenters and electricians. Evans and the others liked the straw-bale building so much they eventually built four others over the years. One is an outbuilding (for storage), one is a barn, one a garden gazebo and one an office. The most recent straw-bale building they erected was their visitor center. That was built last year. "I like the way they feel inside," Evans said. "The sound quality inside is good and there's sort of an organic feel to them."

BY NICK HARDER The Orange County Register

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