What is a straw bale home? On the outside, a straw bale home looks a lot like an adobe house in the southwestern United States. If you peeked inside the walls, though, you'd find 18-inch thick straw bales stacked like bricks and covered with a mesh reinforcement instead of the standard framing lumber, synthetic insulation and plastic vapour barrier. The walls are covered with a thick coating of cement-lime or earthen plaster, and a permeable interior finish and exterior water protection completes the seal.
There are two basic styles of straw bale construction: load-bearing and post and beam. While post-and-beam buildings feature a structural framework that supports the roof and upper storeys and uses the bales as infill, a load-bearing building uses the bale walls themselves for support.
Besides the walls, straw bale homes use mostly conventional construction techniques. The foundation, floor and roof are largely off-the-shelf components; the heating system can use standard or green technology and the electrical and plumbing configurations are similar to a typical custom-built house, with some modifications. Homes can be bungalows or two storeys and range in size from a few hundred square feet to several thousand. Most have conventional mortgages and insurance.
The similarity to convention ends here. According to Pat Marcotte, owner of Havencraft Homes, in Bancroft, Ont., straw bale building offers opportunities for creativity not otherwise available or inspired in standard construction. Archways, barrel vaults, niches and deep window benches are common features in straw bale designs. "The straw can be manipulated into almost any configuration," adds Wise. "The limits are in your imagination."
Dollars and cents The cost of building a straw bale home is comparable to building a custom home, averaging approximately $150 per square foot, though factors such as the complexity of the design and amount of voluntary labour affect the final price tag. For example, many projects involve a bale-raising weekend in which friends and family help build the walls. "It's very much like the olden days of the barn raising," says Tina Therien, a partner with Camel's Back Construction.
The biggest saving is in the reduced energy costs. Straw bale homes have an insulation rating averaging R-40, more than twice that of a conventional-built home. According to a Canada Mortgage and Housing Corporation, or CMHC, survey, straw bale homes use more than 20 percent less space heating energy when compared to conventional homes. They're naturally cool in the summer and retain heat in the winter. In fact, the more extreme the temperatures, the better they perform.
Straw is an abundant, renewable agricultural byproduct that would otherwise be used for animal bedding or be burned. It has a lower embodied energy than conventional building materials (meaning it takes less energy to produce a bale of straw than it does synthetic insulation or engineered lumber) and it's nontoxic, which improves the home's indoor air quality.
Even though straw bale building isn't new (the techniques were first developed by 19th century settlers in Nebraska), when you look at the FAQ section of any builder's website, you'll find the same concerns from prospective clients about fire, pests and rodents, wall strength and rot.
Straw bale homes get a better fire rating than conventionally built homes, passing a two-hour fire test. Straw doesn't attract critters because it has no nutritive value: It's the leftover stalk after the grain has been harvested and is made largely of cellulose and lignin (the same major components of wood.)
 Bale walls are stronger than conventional walls (many century-old buildings and churches in the southwestern United States are still standing today) and when properly maintained, last as long or longer. As long as dry bales are used and the plaster finish remains sealed, straw isn't prone to decomposition or decay.
Getting started While it's getting much easier to have straw bale building construction approved by a municipality today, it's still a good idea to check with local building officials before you buy a property. Most inspectors require architect or engineer approved plans before a permit is issued. Even if you do run into resistance, providing information from credible sources such as the CMHC and OSBBC usually helps with the permit approval process.
The best way to understand the appeal of straw bale homes is to visit one. Every fall, the OSBBC organizes a province wide tour of homeowners who open their doors to interested home builders. "It's an invaluable way of getting out and seeing different designs and talking to owners about what the building process was like," says Therien. "It's also a good way to get references for various builders."
If you prefer a virtual tour, the OSBBC has an extensive online gallery of more than 70 Ontario straw bale homes with notes on the construction method, time to build and even the cost. This site also provides information about upcoming classes, events and workshops, links to technical reports, and lists of member builders, architects and engineers who can help you plan your dream home.
 "I think we all give these grandiose ideas that we're doing this for the earth and the environment but I think we just really like them," says Marcotte. "They just feel nice, they're so comfortable and cozy and they have such a serene feel to them."
Fiona Wagner is a freelance writer in Georgetown, Ont.
-- Posted: April 12, 2007
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