Edmonton runs one of the longest heating seasons of any major city in Canada, and the arithmetic of that is unforgiving: every degree of envelope performance is paid for over more months here than almost anywhere else in the country. That is the case for closed-cell foam in this city, and it is a case about inches, not opinions. Closed cell spray foam insulation in Edmonton wins on R-value per inch where the cavity depth is already fixed.
R-6 an inch is a cavity-depth argument
A standard 2x6 exterior wall gives you about five and a half inches of cavity and no more. Fill it with a material at R-3.5 per inch and the wall tops out where it tops out. Closed-cell at R-6 to R-7 per inch puts a materially higher number in the same stud bay without anyone framing a thicker wall or furring the inside face. On a retrofit where the exterior finish is staying, that is frequently the only lever left. Roughly 59 percent of Edmonton homes were built before 1991, so the stock in question is large and its cavities are already fixed.
Below grade is where the material choice stops being preference
Edmonton basements are deep, the frost goes deep with them, and the wall you are insulating is concrete with soil against the far side. Closed-cell resists moisture rather than taking it on, which is why it is the material used against foundation walls and in crawl spaces where an absorbent insulation would slowly become a problem you cannot see. Two inches gets you roughly R-12 to R-14; three to four inches is the range for R-18 to R-28 where the cavity allows it. It also adds rigidity to the assembly, which is a secondary benefit rather than the reason to buy.
The industrial side of the city
Edmonton's industrial districts - Northwest Industrial, Winterburn, Davies, Roper, Coronet, Clover Bar and Refinery Row among them - are full of steel buildings where the failure mode is not heat loss but condensation on the underside of the deck. Closed-cell adhered directly to steel removes the cold surface that the condensation was forming on, which is a different job from insulating a house and is specified differently.
What has to be true before it goes in
The material has to meet CAN/ULC-S705.1 and be installed to CAN/ULC-S705.2 by a certified installer. In occupied space it needs a thermal barrier over it - 12.7 mm drywall is the usual answer, an approved intumescent coating the alternative. Attics and crawl spaces entered only for service can use an ignition barrier. Spray foam is also rated on long-term thermal resistance, so the number quoted is one the assembly is expected to hold rather than one it starts with.
Closed-Cell Spray Foam Insulation Edmonton: Common Questions
Why does R per inch matter so much here? Because cavity depth is fixed. A 2x6 wall gives about five and a half inches, so R-6 to R-7 per inch reaches a number that a product at R-3.5 simply cannot in the same bay.
Is it required below grade? Effectively yes. Edmonton basements are deep and the wall has soil against the far side, so the insulation has to resist water rather than take it on. Two inches is roughly R-12 to R-14.
What about the industrial buildings? On steel it is the only sensible choice - bonded to the panel it removes the cold surface that interior air was condensing on.
Size the thickness against the assembly you actually have with the spray foam calculator, then get a free Edmonton quote. More on closed-cell foam province-wide.