Promoting power of design for straw bale houses
On first thought the idea of owning a straw house may bring an image of something that is sure to either fall apart or catch fire easily.
Not so, say some building experts.
When straw bales are compressed and designed to be 18-inch walls it is a challenge for any builder to find a material that is more sturdy and secure.
And many fire prevention experts in North America are of the belief that a straw bale and mortar constructed wall is exceptionally resistant to fire. Due to its tight compaction, there is little room for oxygen and almost nothing to fuel any potential fire.
Laura Tanner, a 54-year-old Didsbury resident, is an architectural designer who is convinced straw bale construction is a housing option that is set to take off in the region.
On July 19, she hosted a Straw Bale Building Basics workshop at Olds College during Hort Week.
“I think as sustainability is getting more important and mainstream it is going to be one of many options,” said Tanner of straw bale building. “It has been done all over the world.”
The first documented use of straw bales in construction was in Nebraska when a schoolhouse was built in the late 19th century. Because of its renewable nature, low cost and accessibility, as well as its high insulation value, straw bale construction slowly grew in popularity over the next century, particularly in North America and Europe.
It is still relatively unknown in this region, although Tanner says there is one home in Didsbury she knows about that was built from straw. She also noted there is a triplex in Edmonton that was also built with straw bales and subsequently won an urban design award.
Tanner said she has always been interested in the merits of straw bale construction. She has designed a duplex and a few other homes out of straw, although they have yet to be constructed. Tanner has also helped build two houses made from straw material. More recently she has designed and built a shed from straw bales, a structure that measures 15 feet wide by 18 feet long on the outside. She now uses it as a studio.
When talking about straw bale construction Tanner is quick to emphasize that a straw bale wall is not just straw bales but includes a plaster mix that completes its construction. She notes that a wall made from straw bale and plaster can be 18 inches thick, which she concedes is one disadvantage as it results in square footage loss of a home’s total area, like with her studio which measures only 15 feet by 10 feet on the inside.
She also acknowledges that straw needs to remain dry during construction, which she adds, can be challenging. But Tanner feels all the advantages of straw bale homes, including their insulation value, more than make up for the few shortcomings.
As for cost, the jury is still out with home builders on whether it is cheaper in the long run to build and live in a straw bale home. There is no doubt the premium insulation value brings huge savings but experts in the home construction industry say the cost of building a straw bale home varies depending on design, size and amount of hired labour.
“It is really hard to compare,” said Tanner, whose next project is designing a straw bale home in Boyle, Alta. “Every house is different in cost. It is comparable to a regular framed house but you are getting added insulation.”
For more information on Tanner and her work visit her website at www.dwellingspace.ca