Please ... No ‘Three Little Pig’ Jokes : A Waste Product, Straw Is Being Used to Build Efficient, Affordable Houses
The small, earth-colored house tucked away in the pinon-covered hills outside of town looks like another of the myriad, expensive adobe homes that have sprung up here in the last decade.
Standing in the cool, antique-filled interior, owner Carol Anthony rejoices in its rounded, sculptural lines, describing her recently completed weekend getaway as “a real quiet sanctuary--you feel that you’re really part of the earth.”
But Anthony’s home is very different from those nearby: It was built from straw bales.
With the help of some building professionals, Anthony and her friends stacked the bales like bricks atop a concrete foundation, using mud plaster and stucco to finish the inner and outer surfaces. “It’s really grounded and solid,” said Anthony, a Santa Fe painter who has heard the inevitable “Three Little Pigs” jokes about her house made of straw.
Anthony is among a growing number of homeowners who have embraced the idea of using straw, an agricultural waste product that happens to have superb insulating properties, to build affordable, energy-efficient houses.
But as straw-bale houses have gone up in at least 17 states, including California, many owner-builders have been skirting state or local building codes, which have no provisions for the building technique.
Others, aided by a network of contractors, architects and environmental consultants, have persuaded building officials to allow straw-bale construction on an experimental basis.
In New Mexico, for instance, the state Construction Industries Division has issued permits for 10 experimental straw-bale houses, most of which are due for completion by the end of the summer.
At the same time, the U.S. Agriculture Department has just approved a two-year, $200,000 demonstration program in New Mexico to see whether straw-bale houses really are more affordable.
In California, meanwhile, the state’s first permitted straw-bale house has just been completed in Lone Pine, on Highway 395, in the Eastern Sierra. The 2,500-square-foot passive solar structure includes composting toilets and its own indoor marsh to process gray-water from sinks and showers.
And in the Southland, one highlight of this year’s Anaheim Home and Garden Show will be the 1,800-square-foot straw bale demonstration house being built inside the Anaheim Convention Center. The show is being held through next Sunday.
Despite the recent attention, straw-bale houses have an image problem. For starters, straw is a homely, unglamorous material. And regulatory agencies question the structural strength of straw bales and wonder whether they’re vulnerable to rot and insect damage.
Some of these concerns may arise because straw and hay are often confused.
Hay, which is highly nutritious, is made by cutting and drying grasses and grains, such as wheat, barley, rye, oats and rice. Straw is the dried-out, leftover stems after the grain has been removed and contains few nutrients.
The image problem is an obstacle that Santa Fe straw-bale consultant Tony Perry is determined to overcome.
Perry, a 62-year-old businessman and former British army officer, founded Straw-Bale Construction Management Inc. to assist people in designing and building affordable housing.
It was Perry who led the effort to obtain the experimental permits as part of a program to develop standards that could be incorporated into the building code.
Perry also was the one who approached the Agriculture Department about building demonstration houses, one of which will be put up in a northern New Mexico Latino village, with the other earmarked for an Indian pueblo.
On an afternoon late in June Perry tours a hillside construction site, seemingly oblivious to the shattering heat, discussing the merits of straw-bale construction.
The walls of the 3,200-square-foot home under construction are made of thick, tan bales of straw stacked between concrete-block pillars that will support the weight of the roof.
Perry says straw-bale construction will alleviate the nation’s affordable housing problem while reducing the air pollution generated by farmers burning waste. Straw bales are inexpensive and low-tech--perfect for inexperienced owner-builders, he said.
“Clearly, straw bales lend themselves beautifully to ‘sweat equity,’ ” Perry said. “It’s good for the economy all the way around.”
One of the nice things about straw is its insulating ability, Perry said. An 18- to 24-inch thick wall has an impressive R-54 insulating value. A typical 2-by-4 Fiberglas-insulated wood-framed wall, by comparison, provides about an R-14 insulating factor.
While researching energy costs for the housing proposal he made to the federal government, Perry found it would cost about $800 a year to heat a 1,000-square-foot frame house, but only $200 a year to heat the same size straw-bale house.
Perry got into the straw-bale business a few years ago after his wife, Polly, a local real estate agent, joined a community affordable housing task force.
When straw-bale houses were suggested, Perry immediately took to the idea.
Perry’s concept of “sweat equity,” which is integral to his demonstration models, calls for an owner and friends to contribute much of the labor, both in the wall-building phase (something akin to an old-fashioned barn raising) and in the finishing stages.
Using contractors to pour a foundation and to install electrical connections and plumbing, as well as having one experienced builder on site, Perry estimates an owner-built straw-bale house would cost $35 to $40 a square foot. That’s a substantial savings compared to the $140 to $150 per-square-foot cost of a custom-built adobe home in Santa Fe.
Robert M. Unthank, director of the Construction Industries Division, credits Perry with driving the process to get experimental permits for straw bales.
“If in fact it can be useful for affordability, then we absolutely want to promote it as a building material,” Unthank said. “If there’s anything you can do with this stuff other than burn it, you’re probably better off.”
New Mexico has asked the owners of the 10 experimental houses to have their plans reviewed by structural engineers. The CID is inspecting the houses periodically and is installing moisture-sensing devices inside selected straw bales to collect data.
The state also wants straw-bale proponents to have the structures tested for structural integrity, insect infestation, rotting and fire resistance--all concerns when it comes time to finance or insure a structure, Unthank said.
Perry is trying to raise $24,000 to pay for the testing the state has requested. Should the results prove satisfactory, the straw-bale building standards adopted in New Mexico could well prove to be a model for other states, Unthank said.
With all the attention straw-bale buildings are receiving at the moment, few people realize that they’ve been around for nearly 100 years, tucked in out-of-the-way places such as the sand hills of western Nebraska.
Matts Myhrman, a Tucson resident who with his wife, Judy Knox, operates a well-known straw-bale consulting business called Out on Bale Ltd., has made three visits to the treeless sand hills in search of old houses and barns.
Early settlers resorted to straw bales for their structures because lumber was so scarce, Myhrman said. The buildings they erected were remarkably durable. Of one 90-year-old house that has been abandoned since the mid-1950s, he said, “We could make that building livable again. It’s still going strong.”
There are two main methods of straw-bale construction, Myhrman said.
The first is to build load-bearing walls using the straw bales like giant bricks to form a running bond. The walls are knitted together with lengths of steel driven vertically through several courses, then topped with a bond-beam to attach the roof.
This was more or less the method used in the Nebraska structures, Myhrman said.
“It’s really a much purer form,” he said. “For smaller, more modest structures, it’s really the better way to go.”
The more conservative (and more expensive) approach is to build a post-and-beam wooden framework to support the roof load. Straw bales are then fitted into the gaps between the beams to form an insulation barrier, but they carry no weight. This is the method that New Mexico construction officials have required on all experimental homes.
A third technique that has been tried on occasion is to build a structure using conventional methods, such as wood frame or concrete-block, then “wrapping” it with a straw-bale outer wall.
With that approach, “They’re really using the bales for insulation,” Myhrman said.
In all three systems, layers of waterproof stucco are applied to the outer walls, much as they would be to adobe or wood-frame construction. Interior walls usually are finished in plaster.
Myhrman, a 55-year-old Maine native who is a hydrologist by training, first learned about straw-bale building in 1988 when he stumbled across a story about a straw-bale house in Gila, N.M., in a perma-culture newsletter.
He was especially intrigued by the story’s claim that the house had been owner-built for about $5 a square foot. He contacted the home’s builder, Steve MacDonald, for particulars.
“Within 10 minutes I was totally convinced it was the way I wanted to build,” Myhrman recalled.
Most important, he said, is the savings in labor and materials.
A three-string straw bale about 24 inches wide, 16 1/3 inches high and up to 47 inches long, weighs about 80 pounds and costs about $3.50, he said.
It would take about 300 such bales to create the walls for a 2,000-square-foot house that was rectangular or square in shape, he says. The total cost for materials: less than $1,100.
What’s more, with plenty of help, 8-foot-tall walls for an entire house can be completed in a day or two, he said.
“It’s a wall system that anyone who can pick up one end of a straw bale can help build,” Myhrman said. “It almost demands community, in the sense of a wall raising.”
But Myhrman and others in the straw-bale business caution that the cost of putting up a building’s walls account for only 10% to 15% of the total cost, so substituting straw bale for wood-frame construction does not by itself save that much money.
Other savings come from adopting simpler designs and encouraging owner-builders to join in putting the finishing touches on the house.
While straw-bale construction offers a host of benefits to owners, proponents say it also offers a solution to some thorny environmental problems.
David Bainbridge, a San Diego solar energy consultant who has written an informative manual on straw-bale construction, points out that if straw bales come into wide use, they could eliminate the need for much of the lumber currently taken from old-growth forests.
At the same time, Bainbridge said, farmers would not have to burn as much of their excess straw if they could bale some of it and sell it for home-building.
“The burning of the rice straw in the Sacramento Valley produces more air pollution than all the power plants in the state of California,” Bainbridge said.
Nationally, some 200 million tons of straw are burned in the fields each year, he said.
Bainbridge, who has networked extensively with other straw-bale advocates, says the first international straw-bale conference will be held in Arthur, Neb., this fall. He’s amazed by the speed with which straw-bale building methods have spread.
“For something that’s been basically unfunded by anyone, it’s doing pretty well for itself,” he said.
For More on Straw Houses
Sources for information on straw-bale houses:
--Tony Perry, president, Straw Bale Construction Assn., 31 Old Arroyo Chamiso, Santa Fe, N.M. 87505. (505) 989-4400. --Pliny Fisk III, Center for Maxium Building Potential Building Systems, 8604 Webberville Road, Austin, Tex. 78724. --Matts Myhrman, Out On Bale Ltd., 1037 E. Linden St., Tucson, Ariz. 85719. --David Bainbridge, Biology Dept., San Diego State University, San Diego, Calif. 92182. --Steve MacDonald, P.O. Box 58, Gila, N.M. 88038.
