Project Spotlight: Collective Carpentry
Craig Toohey finds prefab walls for a comfortable, cozy, and quiet Passive House in eastern British Columbia
Erik Olofsson of Erik Olofsson Construction has a vision of elegant and affordable design of the highest quality, reaching the Passive House standard for customers in his harsh Canadian climate. Erik enlisted the help of Vincent Siu of Siu Architecture for the schematic design, and sought to deliver a highly predictable result with the prefab process - delivered for the client, a former mayor of this former lumber mill town of 1,000 in picturesque Valemount, BC, Canada.
Erik selected Collective Carpentry located in Invermere, British Columbia, about a 3 hour drive from Valemount, to make the panels. Panelized enclosures are gaining ground in Passive House circles and Jan, Rane and the rest of the crew at Collective Carpentry are leading practitioners. We were happy to finally have 475's Craig Toohey get to visit Erik's building and the Collective Carpentry shop to get a closer look at their work.
Why a Passive House?
Valemount is located in eastern British Columbia, right near the Alberta border. It’s about 200 km northeast of Kamloops, and not far from Mt. Robson, the tallest mountain in the Canadian Rockies. It used to have a timber mill that produced dimensional lumber, but that’s long gone. Now, according to Andru McCracken, former mayor of this town and owner of the Valemount Passive House, it isn’t home to much industry per se – more so just whatever its residents bring to the proverbial table. His neighbours run a brewery, a Swiss bakery, and other local businesses. Andru came here and started a newspaper. And now prints a phone book. That’s right – prints. A paper phone book. Why? Because he believes in being connected by community, in the value of buying local, and one thing’s for sure: he definitely believes in mountain biking, as we can tell from the cover of the up-to-date, August issue of the publication, featuring a local pro rider who gives her praise of the new mountain biking infrastructure in the towering green mountains hills surrounding the small, sandy-soiled town located on an old aquifer.
In talking to Andru about what drove him to this type of construction, we were perhaps a little bit thrown off but not surprised when we learned about the number one thing Andru was looking for when he first learned about the Passive House methodology and wondered whether it would be for him: quiet. That sandy soil creates quite a rumbling noise with the constant flow of freight trains coming through Valemount. And with his super thick walls and triple-pane, Austrian windows, that’s exactly what he got. You can barely hear the trains from inside the 1,800 square foot house as they roll through town.
But in this house, Andru also achieved a number of other things. He was able to live by his belief in sourcing local materials as much as possible – as evidenced by the slate countertop from the old pool table from the local legion, and the soft pine cabinets in the kitchen. He now lives in a super efficient building thanks to an airtight wall system that's super insulated and 22" thick. He has a bright, open space, while maximizing the solar gains from efficient glazing in this town where -3.6 degrees Celsius is the average temperature. He went for a much smaller footprint than most new builds, which tend to be huge energy hogs in the hills, whereas the Valemount Passive House is right in the center of town, in a walkable location with plans to adorn the sandy soil with native vegetation instead of pumping needless gallons of water to keep up a “healthy” green lawn. And in a town where there’s no natural gas infrastructure and most homes heat with wood, he built an all-electric home which will cost a fraction to heat, and which probably won’t require any active cooling at all. On a toasty summer day in mid-August, the indoor temperature was a cool 75, with a nice consistent temperature throughout the house.
Taking construction off the job site
Obviously one of the most striking things about this house – especially in contrast to his neighbors’ more traditional homes – is its compact design, which allowed the designer to minimize thermal bridging. But if you were there for the on-site work, you would have noticed something else striking – it went up fast! But speed of construction wasn’t necessarily the number one motivator for bringing construction off-site and into a factory. For Rane Wardwell and Jan Pratschke, owners of Collective Carpentry, the decision is actually more about preferring to build inside. It means that their level of quality is higher, their number of interruptions and staff sick days lower, and their use of materials much more economical and less wasteful.
After Jan designs the panels in Cadwork and – using its optimization function – generates cut lists, Rane takes the process to the staging tables where the interior 2x4 structural wall is fabricated, followed by a layer of OSB sheathing (with seams taped on the outboard side) as an interior airtight layer, and an I-joist outrigger “insulation blanket” cavity is added to the exterior. (The interior 2x4 wall will act as a service chase, and in this project, Erik will also add Roxul batt insulation to fill the cavity).
Then, without adding another layer of sheathing, Pro Clima’s Solitex Mento Plus 10ft-wide monolithic, vapor open, airtight WRB membrane is stapled to the I-joists, seams taped with airtight, vapor open Tescon Vana acrylic adhesive tape. Behind it, they’ll use dense packed cellulose to fill the 16" cavity, with the Mento Plus’s reinforcement grid able to handle the pressure of the cellulose as it is blown directly behind the membrane, with holes later sealed with tape (see our ebook on High Performance I-Joist Construction here). This will give them an R-59 wall that's effective at that value because it's encapsulated with airtightness on all 6 sides. Finally, they add vertical 1x strapping for a ventilated rainscreen, and another layer of strapping perpendicular to that to allow for the on-site installation of the vertical Shou Sugi Ban siding. (We should mention at this point that Collective Carpentry builds many other wall types, sometimes for example using wood fiberboard as continuous insulation, depending on the needs of designers/clients).
As each panel comes off the production line in their modest warehouse in Invermere, it is stacked horizontally and tarped to await shipping to the job site. Once on the job site, the panels are put into place by a crane – you have to check out the video below to see this for yourself. Windows are then installed and taped, and finishes follow. With excellent quality control and a simple on-site process, the use of pre-fabricated wall components for the building envelope is a trend we certainly will be seeing more of. This is the future of construction.
Blower door tested at 0.2ACH50 and outfitted with a Zehnder ducted HRV, this is one tight, healthy home.
Spreading the good word.
So what does Andru think the future of Passive House buildings like his? He’s waiting for the ultimate test – the first winter – but is excited to share the philosophy of reducing heat demand with those in his community. With many folks switching from wood or propane to ridiculously expensive electricity bills at sometimes $400-$500/mo, he thinks it won’t be long before many start to see the value of a high performance home.
Andru has been enjoying the fall of 2016 so far:
I can also say the house is performing really well this fall. It's unusual to have a house so consistently warm in Valemount. Typically it's blazing by the fire (only when it is cold enough to warrant) and cool to cold everywhere else. Guests coming in out of the mild cold of October always comment on the warmth and comfort as they step in the front door. Someone asked if we had a wood stove the other day!
A funny story, the baby room was way warmer than the others in September. We didn't know why, was it body heat from the baby, that particular window? My wife was using a desk lamp as a night light by the crib (which may have been left on all day). We knew we got to the bottom of it when we swapped it out for a 0.2w LED night light and the room cooled off. The desk lamp was 20 watts.
Photo courtesy of Erik Olofsson.
~Shout outs go to Erik for connecting me with Andru, to Andru for giving me a tour of his house, Jan for showing me around their shop, Tomaz Stich (a local Passive House consultant) and his wonderful family for giving me a place to stay in Invermere, and the stunning Mt. Robson Provincial Park and the surreal Jasper National Park for a breathless backpacking trip to remember! - CT~
Find Collective Carpentry on Instagram to see what they're up to today:
I wrote this post after an unforgettable trip around the Pacific Northwest. While places I visited like Tofino, Kamloops, Nanaimo, and Seattle aren't included below, the photos I have included are just some shots of the area right near Valemount - a stunningly beautiful part of the world. Enjoy! -Craig