Spinning homes from straw

Kelly Gray and Rick Winklmeier are spinning their dream home out of straw.

The two-level 1,500-sq.-ft. house doesn't look that different from its neighbours from the outside, apart from being bigger than average. There aren't many surprises inside, either — scaffolds, drywall, wood and dust, like any other home under construction.

But if you'd been here last June, you'd have seen a strange sight: a huge crane lifting into place half-tonne wall panels made of straw bales and plaster.

It all started when Gray, an environmental biologist, heard about straw as a green building material. The young couple did years of research, and learned that it was a great insulator, renewable and chemical-free.

"The idea just kind of stuck with us," Gray says. "All the ideas kept snowballing from that."

Now they're building what is probably the greenest house in St. Albert. The Braeside home has super-insulated walls made from straw, Styrofoam and recycled cotton, solar hot water panels, and almost no toxic chemicals. It's also the first straw-bale house in St. Albert, according to city staff.

It hasn't been easy or cheap, Winklmeier notes. It's taken months of work, and they've already spent about $100,000 more than they'd hoped.

"Despite all the difficulties, I think we're still in love with the idea," he says. "It's going to be our little baby."

An old, new idea

The house might look like the one Stan and Marlene Albers built just southeast of Alberta Beach when it's finished.

Seated at their round kitchen table, the Albers say they built their 1,200-sq.-ft. straw-bale retirement home in Golden Glen Estates about seven years ago.

The home looks pretty ordinary: it's got tile, drywall, plants and sofas, plus the usual knick-knackery hanging from the walls.

"You wouldn't know it was straw apart from the windowsills being so wide," Stan says.

Stan and Marlene say they grew up around straw buildings living on the farm. "My father lined the calf pen on the farm with straw bales," Marlene recalls, and that kept the cows warm all winter.

But it wasn't until one of his neighbours raised the idea that Stan decided to build one.

"He lays up at night and dreams up these things," Marlene says. "He still wants to build a house out of used tires!"

Straw homes have been around for centuries, arriving in North America during the 1870s with the invention of baling machines, according to straw-bale guru Chris Magwood.

Straw-bale homes are essentially the same as regular ones, says Don Fugler, who has studied them extensively for the Canada Mortgage and Housing Corporation (CMHC), except they used baled straw for insulation. Most have wood frames with bales stacked in the gaps, but some are frameless, relying on the bales themselves to support the house. All are covered with a thick coat of plaster for support and weatherproofing. They're pretty rare in Canada, with most experts numbering them in the low thousands.

Peter Zuurdeeg has been working with straw-bale homes for about a decade. Five years ago, the Indonesian forester started Go Green Ltd. in Onoway to make pre-built straw-bale walls.

"This is the heart of the operation," he says, as he enters his warehouse. On one side, he's got a ziggurat's worth of rectangular straw bales. On the other, there's a house-sized wall of straw bound in a wooden frame lying on a tilted hydraulic table.

It's relatively easy to build with straw, Zuurdeeg says: you stack the bales, compress them, and cover them with plaster. "You can set up all the walls in a weekend easily," he says. "That's the beauty of straw-bale building: it's so simple that anyone can do it."

Spinning straw …

Straw-bale walls give homes excellent insulation, according to the CMHC — most have a rating of at least R28, compared to about R14 for a regular wall. (R-values rank a substance's resistance to heat transfer from 1 to 100. A R28 wall loses half as much heat as a R14.)

The thick, tightly packed straw combined with the plaster shell makes the wall an airtight slab, stopping most heat-sapping leaks.

The walls themselves are very heavy, Fugler notes — Zuurdeeg's weigh about two tonnes each — which gives them considerable thermal mass. That means they take longer to heat up and cool down, resulting in a home with a steady temperature.

The end result is less energy used, Fugler says. Straw-bale homes use about 20 per cent less energy than regular ones, according to the CMHC.

Straw is also renewable. Trees take decades to form, Zuurdeeg notes, and oil takes millennia. "You can grow straw every year." The straw itself contains no harmful chemicals, he says, and, unlike fibreglass insulation, has a tiny carbon footprint.

It's also fireproof. "If you put a match to this loose straw," Zuurdeeg says, grabbing a handful of it, "it will burn real fast." Loose straw is mostly air, which makes for quick fires. Baled straw, especially once compressed in a wall, has little air in it — you could take a box of matches to a bale and still not burn through it.

Add a layer of inflammable plaster, and you've got an essentially fireproof wall. Tests by U.S. labs suggest that the walls can withstand fires of up to 1,003 C for two hours without any burn-through.

And if you're worried about the Big Bad Wolf, you might like that the walls are windproof. A 1999 test by Texas Tech University found that the walls could stop a seven-kilogram two-by-four plank moving at 160 kilometres an hour — equivalent to a fierce tornado.

… into gold?

One of straw's big selling points is cost. A bale costs about $2, Zuurdeeg says, so you can save a lot of money on the cost of your walls.

But walls only make up about a quarter of the cost of a house, Fugler says — you still need a roof, interior walls, a foundation and labour. "There's a lot of the house that has nothing to do with straw-bale walls." CMHC research suggests that a straw-bale house will cost about as much as a regular one.

Stan and Marlene built their house for about $70,000, but that was because they did almost all the work themselves. "If you'd get a contractor to build the same house," Stan says, "it'd probably be double that."

A regular house would have only a fraction of the insulation of a straw one, Zuurdeeg says. An 1,800-sq.-ft. home with the same level of insulation as a straw house would cost about $30,000 more, he estimates.

Straw-bale walls probably cost more, Winklmeier says, but you get what you pay for. "We're going to have a healthy house with low chemicals, and it's going to be sustainable."

He and Gray ran into one of straw's other problems during construction: mould. Construction delays left their walls roofless during heavy rains, saturating some of them with moisture. "That was kind of our worst nightmare." They had to call in the manufacturer from Saskatchewan to carve out the wet bales and plaster in new ones.

Mould isn't that big of a problem for straw, Fugler says. CMHC studies of straw-bale homes found mould in some walls, but also found that the mould was due to design flaws that would also cause mould in a regular house.

"If you're building correctly and you build well, you shouldn't have mould problems in a straw-bale house."

Straw-bale homes are a niche idea, Winklmeier says, one that is now up against new technologies like insulated concrete. "It's more of an interesting idea that not everybody is going to latch onto." Still, he says he's met plenty of people who are considering it.

It comes down to what you like in a home, Gray says. "It's a very personal choice, I think."