My husband and I recently bought a 120-year-old cottage on an island in the Atlantic. We thought it was a fixer-upper. Turns out, it was a tear-it-downer, according to the myriad experts we hired to look behind the horse-hair plaster walls coated in lead paint. With a rebuild looming, we’ve been considering more sustainable possibilities. These three increasingly popular options are an investment, but they’ll save you money in the long run.
Option 1: An Earthship (what the heck is that?)
Though they sound a bit sci-fi, Earthships are constructed from recycled and upcycled materials that rely on thermal mass and passive solar to be habitable (and sustainable).
Craig and Connie Cook built their Earthship near Lake Erie, Ont., out of 1,200 cast-off tires. The tires are packed with sand, which creates thermal mass, explains Craig. The sun warms the sand, then, when the temperature inside drops, the walls release the heat from the sand to warm the house back up. The southern wall of windows maximizes sunlight and creates a greenhouse, where the Cooks grow food year round, including coffee and bananas.
It’s a common misconception that Earthships aren’t suited for the Canadian climate, says Matt Code, another Earthship inhabitant near Georgian Bay, Ont. Craig agrees. “No matter what happens outside, it’s 70 degrees in our house. It can be minus 30 outside and it’s 70 degrees inside.” Earthships share a lot of design similarities: both Matt’s and the Cooks’ floors are poured concrete. The Cooks also added colour and stamped it to mimic flagstone. But the best part, says Craig, is that, thanks to a cistern to collect drinking water that runs off the metal roof, a handful of solar panels, and no furnace or cooling system, they have no bills related to running the 3,000 sq. ft. building. And Earthship owners can feel good about their footprint: “You’re making an entire structure out of stuff that most people throw away,” says Craig. “When I see a mountain of tires, I see a mountain of homes.”
Option 2: Rammed earth
Rammed earth is a process by which aggregate sand, cement powder, keystone, and silt is, yes, rammed into a constructed form—usually plywood with one coated non-stick side—to create your building. The raw material is put into the form damp, says Dave Spolnik, an architectural designer with Sprout Studios in Huntsville, Ont. “Instead of cement powder,” he says, “the ramming is what gives it strength.”
The process is done in stages. In goes your raw material, including insulation material if you choose. Ram. More raw material. Ram. Each layer is called a “lift.” The result is Pinterest-worthy, “a beautiful organic look, and all of the striations are the product of rammed layer after layer after layer,” says Spolnik. Then, he says, it hardens like concrete.
Though it’s a labour-intensive process, with your rammed earth walls, Spolnik explains, “you’ve got your exterior finish, your insulation, and your interior finish done.” And (here come the physics) because the wall is so big, it has significant thermal mass, says Spolnik, holding and retaining ambient temperature, whether hot or cold. Rammed earth also boasts other environmental bonafides, because most materials can be locally sourced. The challenge? “You have to plan everything,” says Spolnik. “There’s no adjustment if you make a mistake.” It’s that permanence, though, that offers advantages too. “You’re not going to need to replace it in five years or maintain your finish,” he says. “Plus, it’s healthy, with no off-gassing. It’s a super-efficient, super-insulated system.”
Option 3: Forget the fairy tale. Straw beats brick for sustainability
Though Earthships and rammed earth construction are relatively rare, straw bale homes have entered what Deirdre McGahern, the owner of Straworks in Peterborough, Ont., calls “a mature stage.” “Builders have worked out the kinks and developed pretty slick systems for building bale walls,” she says. “We’ve figured out how to make it less labour intensive, and how to make the walls air-sealed, which is key.”
Bale walls are straightforward—straw is tightly packed for insulation and then plastered over, creating an organic feel, with deep window sills. They’re also highly efficient with an R-value around R30, typically double that of more traditional insulation. Bale also earns green cred, because straw is an agricultural waste product that has already absorbed carbon in its growth. “It acts as a carbon sink,” says McGahern.
Misconceptions about bale homes, however, abound. “Moisture is people’s biggest fear,” says McGahern, “but bale walls are actually excellent at drying out should they get wet.” With some bale structures now at least a decade old, McGahern is able to show that moisture hasn’t been a problem. Fire risk is the other major concern people have, she says. But the straw is baled so tightly that combustion is difficult. In fact, bale walls offer a two-hour fire resistance rating. The facts don’t lie: for cottagers who may be considering their options, says McGahern, straw bale buildings are “tried and true.”
Okay, but let’s talk cost and permits
Costs will vary, depending on square footage and materials. The Cooks spent $70,000 on materials, plus added labour costs. Matt Code paid $360,000 (doing most of the work himself and only hiring out the trades). For rammed earth, architectural designer Dave Spolnik says expect to pay more than conventional framing, but costs will be similar to that of wood framing with stone exterior. Straw bale builder Deirdre McGahern estimates costs at approximately $45 per sq. ft. of exterior wall. In addition to your building permit application, be prepared to provide drawings stamped by a mechanical and a structural engineer, as well as plans from an architect, which can run $5,000 to $10,000 each. You may also require an Alternative Solutions submission to prove how your structure will meet code. Rules vary in each municipality—involve a building inspector early, even before you purchase land, if possible.—Alysha Vandertogt