Most of what gets written about spray foam in Calgary is about closed-cell, because the chinook freeze-thaw argument is the loud one. Open-cell is the quieter product in both senses, and on a sizeable share of Calgary jobs it is the correct one - not the compromise. Open cell spray foam insulation in Calgary is the correct choice on a large share of jobs, not a compromise.
What half-pound foam actually is
Open-cell is a low-density foam, roughly 0.5 lb per cubic foot against closed-cell's 2 lb. It carries R-3.5 to R-3.8 per inch rather than R-6 to R-7, it stays soft, and - the part that decides most specifications - it is vapour-permeable. It is not a vapour barrier and it never becomes one no matter how thick it goes. That single property is why it belongs on the inside of a building and nowhere near a below-grade wall or an exposed floor.
Where it wins in a Calgary house
- Interior partitions and demising walls. Sound is the job, and the softer open cell structure absorbs it better than a dense foam does. Media rooms, home offices and the wall between a house and an attached garage are the usual candidates.
- Bonus rooms, for noise rather than heat. The bonus room over the garage is a closed-cell job underneath the floor for thermal reasons, and frequently an open-cell job in the partition walls for acoustic ones. The same room can want both products for different surfaces.
- Budget attics. R-38 takes about six inches of closed-cell or about eleven inches of open-cell. In a vented attic where depth is free, the cheaper material reaching the same number is simply better value, and any quote that refuses to say so is selling density rather than performance.
Where it is the wrong answer
Basement walls, crawl spaces, rim joists, exposed cantilevered floors, anything below grade, anything bonded to steel. Open-cell absorbs moisture rather than resisting it, so putting it into an assembly that will see liquid water or a strong vapour drive is not a saving, it is a future callback. In a Calgary basement the material that belongs against the concrete is the dense one, and the cost difference is the price of it lasting.
Code still applies
Foam facing occupied space needs a thermal barrier over it - 12.7 mm drywall is the standard answer, an approved intumescent coating the alternative. An attic or crawl space entered only for service can use an ignition barrier instead. Open-cell falls under its own CAN/ULC standard rather than S705.1, which governs the medium-density product; the installation expectations are no looser for being the cheaper material.
Open-Cell Spray Foam Insulation Calgary: Common Questions
When is open cell the right choice in Calgary? Interior partitions, media rooms, home offices and the wall against an attached garage - anywhere the job is sound rather than exposure. It is softer and open-structured, which is what absorbs noise.
Can I use it in the attic to save money? In a vented attic with headroom, yes. R-38 is about eleven inches of it against six of the dense product, and depth up there is free.
Where must it never go? Below grade, in a crawl space, on a rim joist or bonded to steel. It is vapour-permeable and absorbs moisture, so those assemblies need the dense product at any price.
Roughly 52 percent of Calgary homes were built before 1991, and in that stock the walls are frequently the noisiest part of the house long after the heat problem has been solved. Work out what thickness gets you where you want with the spray foam calculator, then get a free Calgary quote. More on open-cell foam province-wide.