Spray Foam and the Building Code in Canada: What to Know

Spray foam is a high-performance insulation, but it is also a plastic, which means the building code treats it carefully. If you are planning a spray foam project in Canada, it helps to understand the main rules: foam in living spaces usually needs an approved thermal barrier, the material and installer must meet the CAN/ULC-S705 standard, and vapour barrier requirements still apply. Codes are written nationally and then adopted province by province, so the exact details vary a little between Nova Scotia, New Brunswick, PEI, Newfoundland and Labrador and British Columbia. This guide explains what to expect.

For the bigger picture on how foam compares to loose-fill, see our pillar guide on spray foam vs blown-in insulation. Here we focus on the code requirements that a proper spray foam installation must satisfy.

Why does spray foam need a thermal barrier?

Spray foam is combustible, so the code requires that foam in living spaces be separated from the interior by an approved thermal barrier. The most common thermal barrier is 12.7 mm (half-inch) drywall, which slows the spread of fire and gives occupants time to escape. This is why you cannot simply leave sprayed foam exposed on a finished basement wall or in a living area. The barrier must cover the foam on the room side.

In some spaces that people do not normally occupy, such as attics and crawl spaces, the code may allow an approved ignition barrier instead of a full thermal barrier. An ignition barrier is a thinner protective coating or covering tested to limit flame spread. Whether a thermal barrier or an ignition barrier applies depends on the space and how it is used, which is one reason a knowledgeable installer and your local building official should confirm the detail before work begins.

What is CAN/ULC-S705 and why does it matter?

CAN/ULC-S705 is the Canadian standard for medium-density closed-cell spray polyurethane foam. It comes in two parts: one part sets the requirements for the foam material itself, and the other sets the requirements for installation. Standards like this are developed within Canada's national standards system, overseen by the Standards Council of Canada (scc-ccn.ca). When a building official asks whether your foam meets code, they are essentially asking whether it was an S705-compliant product installed to the S705 method.

A major part of S705 is that closed-cell spray foam must be applied by a licensed or certified installer working under a quality assurance program. Certified installers are trained to mix the two foam components at the correct ratio and temperature, spray in proper passes, and document conditions on site. This is not red tape for its own sake: most spray foam failures, including the cure and odour problems that lead some homeowners to remove foam, trace back to off-ratio or rushed installs. Hiring certified crews is the single best way to stay on the right side of both code and quality.

What is a CCMC evaluation?

The Canadian Construction Materials Centre (CCMC), part of the National Research Council, evaluates building products and issues evaluation reports that confirm a product meets the intent of the National Building Code. For spray foam, a CCMC evaluation number gives building officials confidence that the specific foam has been independently assessed for properties like R-value, air leakage and fire performance. Natural Resources Canada (natural-resources.canada.ca) and provincial programs often reference these evaluations when products are used in rebate-eligible work. When you get a quote, it is reasonable to ask which product is being used and whether it carries a current CCMC evaluation.

Do I still need a vapour barrier with spray foam?

This is one of the most useful things to understand. Closed-cell spray foam at sufficient thickness acts as its own air barrier and vapour retarder, so in many assemblies it removes the need for a separate poly vapour barrier. Open-cell spray foam, by contrast, is vapour-permeable and usually still needs a separate vapour control layer where the code requires one. Because Canadian climates push moisture from the warm interior toward the cold exterior in winter, getting the vapour control right is essential to avoid trapping moisture inside a wall or ceiling. A qualified installer will design the assembly so the foam type, thickness and any vapour barrier work together.

• Thermal barrier: usually 12.7 mm drywall over foam in living spaces.
• Ignition barrier: a thinner approved covering allowed in some attics and crawl spaces.
• CAN/ULC-S705: the material and installation standard for closed-cell foam.
• CCMC evaluation: independent confirmation the product meets code intent.
• Vapour control: closed-cell can serve as its own retarder; open-cell often needs a separate layer.

How do provincial codes change things in Atlantic Canada and BC?

Canada publishes a model National Building Code, but it only has legal force once a province adopts it. Nova Scotia, New Brunswick, Prince Edward Island, and Newfoundland and Labrador each adopt and adapt the national model, and British Columbia maintains its own BC Building Code based on the national model with provincial changes. In practice the spray foam fundamentals, thermal barriers, S705 and vapour control, are consistent across these provinces, but minimum R-values, permit steps and inspection details can differ. Always confirm requirements with your local building department, since they enforce the version of the code in force where you live.

Code compliance also protects your home value. A documented, code-compliant installation is far easier to explain to a buyer or home inspector, which we discuss in does spray foam insulation affect home resale value. Before you sign anything, it is also worth reviewing our checklist in what to ask an insulation contractor so you can confirm certification, product evaluations and barrier details up front.

What do the energy code and air barrier rules add?

Beyond fire safety, the code also cares about energy performance. Modern Canadian construction requires a continuous air barrier in the building envelope, and this is one area where spray foam shines: closed-cell foam at adequate thickness can serve as that air barrier, sealing the gaps and penetrations that loose-fill cannot. The code also sets minimum effective R-values for attics, walls, basements and crawl spaces, and these minimums are generally higher in colder regions. Because spray foam delivers a high R-value per inch, it is often used where space is tight, such as rim joists, cathedral ceilings and shallow crawl spaces, to hit the required R-value without losing room. When your installer designs the assembly, they balance the fire, air barrier, vapour and R-value requirements together so the finished wall or ceiling passes inspection and performs for decades. Keeping copies of the certification, the product data sheet and the CCMC number with your home records makes future inspections and rebate claims much smoother.

What should homeowners do before a spray foam project?

Start by hiring a CAN/ULC-S705 certified installer and asking which CCMC-evaluated product they will use. Confirm whether your space needs a thermal barrier or qualifies for an ignition barrier, and how vapour control will be handled. Check whether a building permit is required for your scope of work, and keep the documentation, since provincial rebate programs and future buyers may ask for it. It is also worth confirming whether your work qualifies for provincial rebates through programs such as Efficiency Nova Scotia, Efficiency PEI, New Brunswick energy savings programs, takeCHARGE in Newfoundland and Labrador, or CleanBC Better Homes, since most require a code-compliant, documented installation. Greenfoot installs spray foam to code across Atlantic Canada and British Columbia, and we are happy to walk you through the requirements that apply to your specific project.