Canada’s steel garage construction sector is adjusting to tighter thermal performance rules after Ontario’s 2024 Building Code took effect January 1, 2025, introducing updated SB-12 compliance pathways with stronger airtightness requirements for accessory structures , a regulatory shift that industry observers expect other provinces to follow as the country pursues net-zero building commitments.
The code change has renewed focus on fibreglass blanket insulation, which remains the most widely used method for meeting energy performance targets in steel garage buildings across Canada’s harsh climate zones. Demand for proper installation guidance has risen as builders and homeowners confront both new code minimums and climbing energy costs.
Fibreglass blanket insulation, sold in rolls or pre-cut batts, delivers between R-3.0 and R-3.7 per inch of thickness, according to Natural Resources Canada. For a heated steel garage in Climate Zone 6 , covering most of Ontario and the Prairie provinces , contractors typically target wall assemblies of R-20 or higher and ceiling values of R-40 to R-60 to satisfy code minimums and comfort standards. The product works by trapping a layer of still air between the steel cladding and the building interior, slowing heat transfer in winter and heat gain in summer.
“With the Ontario code update now in force and other provinces watching closely, the decisions builders make at the permit stage carry more long-term weight than they did even five years ago,” said Herbert Broderick,CEO of Metal Pro Buildings . “Fibreglass blankets are still the right starting point for most steel garages , the key is getting the vapour barrier placement and air sealing right from day one.”
A critical early decision is selecting faced versus unfaced product. Faced insulation , blankets bonded to a kraft paper or foil vapour barrier , is the preferred choice for steel garage buildings because it controls moisture migration from the warm interior toward cold steel panels. Under the National Building Code of Canada (NBC) and provincial equivalents, vapour barriers must be positioned on the warm side of the insulation assembly. In steel structures, condensation on the metal is a leading cause of premature corrosion.
“In a steel building, the vapour barrier isn’t optional , it’s the line between a structure that lasts 40 years and one that starts showing rust streaks inside five,” Broderick said. Contractors staple faced blankets between secondary framing members with the vapour-barrier facing oriented toward the interior, then seal all seams with acoustical caulk or purpose-made tape before installing the interior liner panel or drywall.
Cutting is straightforward , a utility knife and a straightedge allow installers to score blankets to any width , but Natural Resources Canada’s guidance stresses that batts must fill the cavity completely, without compression or gaps. Compressing fibreglass reduces its effective R-value and can push a wall assembly below code-minimum performance even when the nominal product rating appears sufficient.
For roof and ceiling planes, blankets are draped over the purlin system before roof sheeting is applied. The steel construction industry commonly uses a “double-layer” system, in which a second run of insulation is installed perpendicular to the first, reducing thermal bridging through the purlins. In Alberta, Saskatchewan, and Manitoba, the NBC Alberta Edition requires RSI 3.08 (R-22) in wall cavities and RSI 10.43 (R-60) in ceiling assemblies, according to City of Calgary climate-readiness guidance. British Columbia’s Energy Step Code pushes requirements further, with some step levels demanding effective values beyond fibreglass alone, prompting hybrid systems that combine blanket insulation with continuous rigid foam.
Fibreglass and mineral fibre blanket insulation does not settle over time when installed correctly, according to Natural Resources Canada, giving it a long-term performance advantage over blown cellulose in wall cavities. Installers are advised to wear gloves, eye protection, and a dust mask during handling, as glass fibres irritate skin and lungs on contact.
Ontario’s code update signals a broader national trend. As Canada’s net-zero building targets advance, insulation requirements for accessory structures historically subject to lighter regulation than primary dwellings are expected to tighten further. Builders and permit applicants are advised to confirm climate zone requirements and any municipal amendments with local building departments before selecting insulation thickness.
