Canadian Winter building requirements

[Dana Walker]

Hi, I fashion a Canadian winter! Having really wanted to move to Canada for a while now, I am wondering what some of the extra requirements are to building in northern British Columbia. What are some of the added costs that tend to surprise first time northern builders? What are some of the added considerations? I feel the answers are going to be quite sobering!

[Roy N.]

Originally posted by @Luc Boiron:

Originally posted by @Roy N.:

@Dana Walker

As Jay indicated, building codes in Canada (as in the snowy parts of the U.S.A.) accommodate snow load.   Sadly, the minimum "code" requirements for insulation (R23 walls / R50- R70 attic) are inadequate and if building new in northern BC  (or northern anywhere), I'd be looking at a minimum insulation load of R50+ (walls) and R100 (ceiling/roof) along with second to none air sealing and mechanical ventilation (HRV).   On the fenestration front, triple glazed windows (casement or tilt-in-turn for the operable windows) with insulated fibreglass frames (if budget allows).   I would also consider using Swedish Framing rather than Western Platform framing (if stick building) or assembling the envelope using SIPs.

The small bit of extra you would spend to effectively insulate and air-seal the building envelope will pay itself back in operating costs in relatively short order.

The codes in this country should really require new builds to be much closer to (eventually at) a Passivhaus standard (perhaps Net Zero as a compromise).

 Wow I wish I could get these R values. I'm currently completely redoing a little cottage (1,000 sqft including walk out basement). Spending over $150,000 in reno's. We pulled out the old mouse infested pink fiberglass. We put an inch of rigid foam on the outside under the new siding. The exterior walls and roof line (conditioned attic loft) were true 2x4's, so we only would have gotten R 14 out of them with fiberglass. We strapped out the roof line with 2x2's but didn't want to strap the walls because we are so limited in space. We spray foamed everything. So we got about an R30 in the roof and about an R18 in the walls, plus the 1 inch of foam on the outside, so about and R23 in the walls. 

The only thing that makes be happy of this is that the closed cell spray foam is such a good vapour barrier and will really seal the house up well. Also had gas at the street so we're switching from baseboards to gas which will make a big difference. 

Still wish I could have gotten a higher R value in this property since we're keeping it as a rental.

Luc:

I used the same approach on a duplex a few years ago: 3.5" of spray foam on the interior and 1.5" of XPS rigid insulation on the exterior.   While it keeps the building very warm, I suspect I have shorted the life of the sheathing dramatically and may eventually have problems with mould in the wall assembly.

Closed cell directly on the underside of the roof deck or inside face of the exterior walls allows you to pack a lot of R-value into a 2x4 cavity (theoretically R22).  However, if you are using closed cell foam on the inside of your wall assembly, I would recommend using Roxul Comfortboard 80 (or an equivalent rock wool board from another vendor) rather rigid foam (XPS or polyiso) as you do not want a strong vapour retarder / barrier on both sides of the wall sheathing.

The other thing to keep in mind is the ratio of "inside" to "outside" R-value.  This ratio varies depending upon climate zone (I'll see if I can dig-up the table and link it in to this post), but in Canada - with the possible exception for parts of Vancouver Island and the lower delta in BC - the target ratio is 1/3 (interior) and 2/3 (exterior).  The objective is to keep the sheathing warm enough to ensure the condensation point always occurs to the exterior side.    If you were building from scratch, ideally all the insulation would be on the exterior of the wall assembly -;)

We are presently retrofitting a wooden, Italianate building (circa 1878 - 1880) and on this one, I am using rock wool in the wall cavities (R22 where I can strap the inner side of the exterior walls and R14 in the places where I cannot (a long narrow corridor, rooms with elaborate plaster crown moulding we wish to retain).  Once insulated, I'll use a variable vapour retarder (such as IntelliPlus or Membrain) on the internal side.  In a couple of years when we do the outside of the building, we'll apply 2" of rigid foam on all three faces and 2" of rock wool board on the fourth (it's a zero property line and non-combustable exterior insulation and cladding must be used).