By Paul Hearsey —
Well, we’ve been here in Horsefly for seven years this month already. How time really does fly! In the June/July issue of TheGreenGazette we told readers all about our gardens, greenhouse, and root cellar. Today, we’ll talk about the house we have been building in our spare time.
Never again. That’s what we said to each other when we first arrived in Horsefly. Building a house on the coast over six years was a tough thing to do, while we both worked full time and raised kids. But while we now owned forty acres (of scrubby, weedy, marginal farmland) our little log cabin was just a few feet from the road. Heavy truck traffic was waking us up at night and making us crazy. So … within months we started looking for a new building site.
I had always wanted to build an off-grid, high-performance home, so we started researching and sketching ideas. We came up with a fairly simple plan, just—1,080 square feet on one level, facing south on an almost unobstructed ridge. Since our funds were limited we had to be smart about this. We designed it in multiples of two feet, so that drywall, siding, and roofing waste was minimal. Simple also meant less labour.
In Canada we build some pretty poor homes. They may cost $400 or more a square foot, with granite countertops and hot-tubs, but they are very, very low performance homes. Energy costs in this country are still too modest. I’m serious: we really don’t pay enough for energy (or water!) to want to try harder. And our “leaders” in Ottawa are so lacking in vision and so focused on themselves, they cannot see that conservation and renewables are vitally important. So we need to take the lead.
We took our inspiration from the Passivhaus program in Germany, where physicist Wolfgang Feist took crude 1970s Canadian ideas about high performance and elevated them to a science. So, since energy conservation must come before fancy high-tech gadgets we designed a home with double wall construction. An outer wall of two by fours would support the roof and ceiling joists, while an inner wall would support the drywall. A space of five inches between inner and outer walls would give us a twelve-inch wall thickness and R38 when insulated with blow-in cellulose. Compare that to standard two by four construction, where thermal bridging and sloppy insulation practices typically result in an R12 wall. Even two by six construction is only slightly better.
Access to our site was not great so after much thought we settled on a shallow frost-protected pier foundation, to avoid the need for concrete deliveries. Ah, the joys of hand-digging hard clay. Twenty-four pressure-treated posts sit on concrete pads just three feet below the surface, and built-up wood beams sit on those posts. A conventional wood framed floor was assembled on top of that. A frost protected foundation uses foam board insulation below the surface to hold both ground warmth and “lost” heat from the house and prevent freezing. No freezing, no frost heaving. No heaving, no cracked drywall. The foamboard was armoured with galvalume metal roofing, which looks far better than it sounds here. Ten inches of Roxul mineral wool insulation minimizes heat loss through the floor, at R36.
Today, a well-designed home uses “smart framing.” This requires thinking. Everything is on two-foot centers and aligned top to bottom, so that loads are transmitted from roof rafters directly to wall studs to the foundation and from there to the ground. This requires less lumber, and allows for more insulation. Many times I’ve seen three to five wall studs in a cluster, just because a builder didn’t know what else to do. Dumb—a permanent cold area in your wall. And what’s with full-size headers over doors and windows in non-load-bearing walls? Is this the 1960s? It’s important to remember that good design doesn’t need to cost extra, and your own research is essentially free. Start by reading Fine Homebuilding magazine at the Williams Lake library.
Our home is a passive solar home, with generous south-facing windows and substantial roof overhangs. Since we put so much effort into super insulating the walls, floor, and ceiling, we installed triple glazed, low-e, argon-filled windows from All Weather Windows in Edmonton. Both Central Builders Supply and Wise Windows are local dealers. Our windows are vinyl framed. Aluminum is far too cold and wood too high-maintenance, and we couldn’t argue with the energy efficiency of these frames so vinyl it was. We installed standard units on the east and south sides, where the higher solar transmittance would ensure maximum solar gain and Sunstop units on the west and north sides where little sun lands. These have a slightly higher R value.
Only three of the 11 windows open, because fixed windows are tighter windows. Although it was a lot of trouble, we splayed the sides of the window openings outward 30 degrees so they felt larger and admitted more light. After much research we settled on 42-inch overhangs to prevent full summer sun from turning our home into an oven.
Lots of thermal mass, typically concrete, can really minimize temperature swings too, but we don’t like living on a concrete floor, even if tiled. Too solid and unforgiving, quite hard on the body. The 7,000 pounds of cellulose surrounding us provide some thermal mass and the drywall provides some too; the house has always remained cool in the hottest summer weather. We installed common galvalume metal roofing up top. Inexpensive, highly reflective in the sun, easy to work with, it was a great choice for a house that would not be getting air conditioning.
Although we used ordinary half-inch drywall on the walls we used five-eighths firestop drywall on the ceilings. The standard drywall would have eventually sagged under the weight of all that insulation (18 inches and R68). Those sheets were about 90 pounds each, so we splurged and bought a drywall lift to make overhead work do-able. We employed the airtight drywall method, with every sheet carefully glued to the framing, and every perforation (electrical boxes, mostly) sealed and re-sealed. Sealing is possibly the most important part of a high-performance project because all the insulation in the world cannot make up for infiltration losses. We caulked and taped and triple-checked every inch afterwards. This was tedious but necessary. Twin four-inch earth pipes some 70 feet away bring fresh air underground to the center of the house. The pipes rise up to the kitchen and bedroom, and because they are buried deep they warm incoming air in winter and cool it in the summer. This is a sort of poor-man’s heat-recovery ventilator, without the power consumption.
For the exterior we went with four-by-eight-foot sheets of HardiePanel, a wood and cement composite product that is insect and rodent proof, and very fire resistant. I like the fact that paint goes further and goes on faster, and should last longer than paint on wood because seasonal movement is almost nil. Vertical battens every two feet will give us a board and batten look while hiding the nails.
Space limitations force me to mention only in passing that we have local wide-plank aspen flooring, no formaldehyde-spewing plywood, particleboard, or MDF, only non-toxic low VOC glues and finishes, fire sprinklers, and LED lighting throughout.
So, we have followed all the modern home-building rules: modest size, heavy insulation, very tight envelope, and passive solar. Total material costs will reach $45,000 or $42 per square foot when we’re finished. In this world of high-tech it’s nice to know that these simple, affordable ideas still make the largest impact when aiming to build a high-performance, low operating-cost home.
In a future issue of The Green Gazette we’ll talk about the off-grid photovoltaic system, our solar hot water, rainwater catchment, and water-conserving appliances.
Paul Hearsey and Sandy McNie live in beautiful, snowy Horsefly. Their interests range from farming and gardening to building design and all things solar. They welcome feedback, questions, and visits. Email them at firstname.lastname@example.org.