Ontario's building code (OBC SB-12) sets minimum insulation requirements based on climate zones. Most of Southern Ontario, including the GTA, falls in Climate Zone 6, which requires R-60 in attics, R-22 for exterior walls, and R-20 for basement walls. Meeting these minimums is mandatory for new construction and many renovation permits.

The right insulation type depends on your application. Closed-cell spray foam offers the highest R-value per inch (R-6.5) and doubles as an air and vapour barrier, making it ideal for basement walls and rim joists. Open-cell spray foam (R-3.7/inch) is more affordable and excellent for attics and interior walls. Fiberglass batts remain the most budget-friendly option for standard wall cavities.

Professional installation is recommended for spray foam insulation, as it requires specialized equipment and training. Fiberglass batts and mineral wool can be a viable DIY option for experienced homeowners, though professional installation ensures proper coverage and avoids compression that reduces R-value.

Frequently Asked Questions

What R-value do I need in Ontario?

Ontario Building Code (SB-12) requires R-60 for attic ceilings, R-22 for above-grade exterior walls, and R-20 for basement walls in Climate Zone 6, which covers most of Southern Ontario including the GTA. These are minimums — exceeding them improves energy efficiency and comfort. Our insulation calculator above determines the thickness and material quantity needed for each R-value target.

How thick should insulation be for R-60?

Thickness for R-60 depends on the insulation type. Blown-in cellulose requires 16–18 inches of settled depth. Blown-in fiberglass needs 17–20 inches. Closed-cell spray foam would need approximately 9 inches, but R-60 with spray foam alone is not cost-effective — it is typically combined with blown-in insulation on top.

How much does spray foam insulation cost per square foot?

Closed-cell spray foam in the GTA costs $4.00–$8.00 per square foot installed, depending on thickness, accessibility, and project size. Open-cell spray foam costs $2.50–$5.00 per square foot. These prices include material and labour. Our insulation calculator above estimates installed cost for all insulation types based on your wall area and R-value requirements.

Insulation Services R-Value Chart