If one product earns its place in an Alberta building envelope, it's medium-density closed-cell foam. At roughly two pounds per cubic foot, it cures hard, bonds to almost any substrate, and does three jobs at once that other insulations split between separate products: it insulates at R-6 to R-7 per inch, it air-seals, and at about two inches it becomes a vapour barrier in its own right.
Why density changes everything
Open-cell foam is mostly trapped air in a soft matrix - great for sound and interior walls, but it drinks water and can't stop vapour. Closed-cell's tight, rigid cell structure flips all of that: it resists moisture, adds structural rigidity to a wall or panel, and holds its rated R-value long-term (LTTR). That combination is exactly what Alberta's freeze-thaw, high-humidity-indoors, bone-dry-outdoors winter demands.
Where it belongs
- Basements & below-grade walls - 2" gives roughly R-12 to R-14 and shuts down the condensation that ruins framed-out basements; 3-4" reaches R-18 to R-28 in tight cavities.
- Crawlspaces - seals the cold, damp floor of the house.
- Rim joists - the single leakiest band in most homes.
- Metal & steel buildings - stops the sweating that drips off an uninsulated metal roof.
- Exterior walls, roofs, tanks, containers - anywhere moisture or structure matters.
Spec and standards
Closed-cell medium-density SPF is manufactured to CAN/ULC-S705.1 and installed to S705.2 by a CUFCA-certified applicator whose photo ID is renewed yearly. The manufacturer's product data sheet governs the exact spec on your job; a good installer specs thickness to your target R-value, not to a rule of thumb. In occupied space it's finished with a code-required thermal barrier.
Not sure closed-cell is what your project needs? Compare it with open-cell, or get a quote and have a vetted installer spec it.