Lethbridge has a large rental and student housing market alongside its older owner-occupied stock, and in shared housing the wall that gets complained about is almost never the exterior one. It is the one between two people. That is open-cell spray foam's job. Open cell spray foam insulation in Lethbridge is bought for the wall between two people, not the one facing the wind.
Soft foam, better sound
Open-cell is a low-density product - about 0.5 lb per cubic foot against closed-cell's 2 lb. It cures soft and open rather than rigid, and that structure absorbs airborne sound rather than transmitting it. On a demising wall between units, a bedroom partition, a stairwell or a mechanical chase, it outperforms the denser and more expensive product at the thing it is actually being asked to do.
The trade-off, stated plainly
Open-cell gives R-3.5 to R-3.8 per inch; closed-cell gives R-6 to R-7. Open-cell is vapour-permeable and absorbs moisture; closed-cell resists it and becomes a vapour retarder at about 38 mm. So the cheaper material is the right answer on the inside of a building and the wrong answer everywhere the assembly meets weather, ground or steel. In a wind-driven climate like this one the exterior air seal matters more than most places, and that is dense-foam work - open-cell does not substitute for it at any thickness.
Attics are the exception worth taking
Depth in a vented attic is cheap. Eleven inches of open-cell reaches R-38, the same target six inches of closed-cell reaches, for less money. About 59 percent of Lethbridge homes predate 1991, and in a lot of that stock the attic is both the biggest loss and the easiest access, so it is where a budget goes furthest. Air-sealing the ceiling plane properly matters more than which product sits on top of it.
The buildings this comes up in
The older core and areas like Varsity Village and Indian Battle Heights carry much of the multi-occupancy housing, while newer areas such as Riverstone, The Crossings and Garry Station tend to raise the question as a home-office or media-room request instead. Either way the specification is the same: interior surfaces, sound as the objective, dense foam left for the assemblies that face out.
Foam facing occupied space needs a thermal barrier over it - 12.7 mm drywall or an approved intumescent coating - with an ignition barrier permitted where access is service-only. Open-cell is covered by its own CAN/ULC standard rather than the S705.1 medium-density one.
Open-Cell Spray Foam Insulation Lethbridge: Common Questions
Why is it common in rental housing here? Because in shared housing the wall that gets complained about is the one between two people, and this is the product that addresses it.
Does it help against the wind? Not as an exterior solution. Wind-driven air movement is dense-foam work; open cell belongs on the inside of the building.
Is it worth using in the attic? Frequently. About 59 percent of Lethbridge homes predate 1991 and the attic is both the biggest loss and the easiest access, so a budget goes furthest there.
Size it with the spray foam calculator, then get a free Lethbridge quote. More on open-cell foam province-wide.