Spray Foam Insulation near you

Both kinds of spray foam are polyurethane, but they behave differently once cured. Natural Resources Canada's retrofit guide describes closed-cell foam, also called two-pound foam, as a product that can serve as an air barrier and, at a thickness of 50 mm (2 in.), can sometimes act as a vapour barrier. Open-cell foam, also called low-density or half-pound foam, can serve as an air barrier but not as a vapour barrier, so in most Canadian walls and ceilings it needs a separate vapour control layer on the warm side.

Spray foam earns its place where a space is irregular, hard to seal or close to moisture. In simpler spots, such as an open attic floor, blown-in insulation is usually the more sensible fill, sometimes over a thin layer of foam that seals the leaks first.

In Canada, medium-density spray polyurethane foam, the closed-cell type, is covered by the CAN/ULC-S705 standards: one part deals with the material and another, CAN/ULC-S705.2, with its application. A product evaluation published by the Canadian Construction Materials Centre (CCMC) at the National Research Council requires that such foam be installed only by certified installers who carry a valid photo-identification licence and can show it on request, under a site quality assurance program with periodic inspections by an accredited third party. Ask to see the installer's card before the work starts.

Certification of the person spraying is separate from the licence of the company. In Quebec, a contractor doing residential insulation work must hold an RBQ licence with the specialized contractor subclass that covers insulation. Elsewhere, check provincial and municipal requirements.

Health Canada notes that MDI-based products such as spray polyurethane foam may cause breathing problems and skin sensitivities, and its advice centres on following the product instructions and safety warnings, including when to leave the area and when it is safe to go back. On a professional job, the installer should tell you in writing, before the work starts, how long everyone, pets included, must stay out of the work area and the house. NRCan's retrofit guide mentions a 24-hour curing and off-gassing period before occupancy resumes for closed-cell foam; the product's own instructions set the time for your job.

Spray foam is a plastic, and like other foam plastic insulation it must be protected from fire inside a home. NRCan's retrofit guide states that plastic-based foam insulation installed on interior surfaces must be covered with a fire-resistant material, typically 13 mm (1/2 in.) drywall. Building codes set out which coverings qualify and where exceptions apply, so the thermal barrier belongs in the plan and in the quote from the start.

This matters most in spaces nobody plans to finish. Foam sprayed on a rim joist or a basement wall and left bare may not meet the code even if the room stays a storage area. Ask the contractor what will cover the foam in each area, whether a special coating is acceptable in an attic or crawl space, and who installs it.

Sealing the rim joist, the basement walls and the roof junctions with foam can close many of the leaks that used to ventilate an older house by accident. NRCan's air leakage guide treats controllable whole-house ventilation and combustion air as part of any serious air sealing job, because humidity climbs as the envelope tightens. Plan the ventilation before the foam goes in, not after the first winter.

Vapour control needs the same forethought. Because closed-cell foam at sufficient thickness can already slow vapour, adding a polyethylene sheet over it can trap moisture between two layers, while open-cell foam usually needs that sheet. Ask the installer to explain which layer controls vapour in each wall. During the first heating season, frost on windows, a damp basement smell or mould in closets means the house needs more fresh air, and naturally vented appliances should be checked for backdrafting.