Spray Foam Insulation in Airdrie: Closed-Cell, Open-Cell & Hybrid Systems

How These Systems Differ

Spray polyurethane foam starts as two liquids mixed at the spray gun and expands into insulation that bonds to whatever it touches. That adhesion is what separates it from batts and loose-fill: it seals the cracks, joints and odd shapes that fibrous insulation leaves open, so it stops air movement as well as slowing heat. In a climate where most moisture damage starts with warm indoor air reaching a cold surface, that matters as much as the R-value. It also means foam is a combustible plastic that has to be covered by a thermal barrier in most places people use.

The two foams differ in almost every practical way. Two-pound closed-cell foam is dense and rigid, commonly about R-6 to R-7 per inch, resists water and at about two inches typically works as a vapour barrier, which is why it belongs on concrete, rim joists, crawl space walls and steel. Half-pound open-cell foam is soft and light, commonly about R-3.5 to R-3.8 per inch, and absorbs airborne sound well, but it lets vapour through and soaks up water, so in this climate it is limited to interior walls and carefully designed assemblies with a separate vapour barrier.

The rest of this family is about using foam intelligently. Flash-and-batt and flash-and-blow systems place a closed-cell layer only where air sealing and condensation control happen, then fill the cavity with less expensive batts or loose-fill. Under-slab insulation, usually rigid board with spray foam around congested plumbing, keeps a heated floor from warming the ground beneath it. Intumescent coatings such as DC315 give exposed foam in shops, barns and crawl spaces an accepted alternative to drywall when they are matched to that foam. Most projects need one or two of these, not all five.