# Ontario Spray Foam Insulation: Open vs Closed Cell, Best Applications & 2026 Costs

**URL:** <https://home.renovation.reviews/t/ontario-spray-foam-insulation-open-vs-closed-cell-best-applications-2026-costs/46865>\
**Category:** Ontario\
**Created:** [April 26, 2026, 6:25pm UTC](https://home.renovation.reviews/t/ontario-spray-foam-insulation-open-vs-closed-cell-best-applications-2026-costs/46865 "2026-04-26T18:25:32Z")\
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**Author:** ![system](https://home.renovation.reviews/user_avatar/home.renovation.reviews/system/32/77_2.png) [@system](https://home.renovation.reviews/u/system)\
**Post date:** [April 26, 2026, 6:25pm UTC](https://home.renovation.reviews/t/ontario-spray-foam-insulation-open-vs-closed-cell-best-applications-2026-costs/46865/1 "2026-04-26T18:25:32Z")

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Spray foam delivers the best combination of R-value and air sealing in Ontario homes. Here is a complete 2026 guide.

**Open Cell vs Closed Cell**  
Open-cell (R-3.5/inch): Softer, vapour-permeable, less expensive. Interior walls and ceilings. Closed-cell (R-6/inch): Dense, rigid, vapour barrier. Rim joists, cathedral ceilings, basement walls, exterior applications.

**Best Applications in Ontario Homes**  
Rim joists: 2 inches closed-cell = R-12 plus complete air seal. Highest return spray foam application in Ontario basements. Cathedral ceilings: Closed-cell prevents moisture accumulation in thin roof assemblies. Basement walls: Closed-cell provides vapour barrier and insulation in one product. Attic penetrations: Seal around pot lights, plumbing, and mechanical penetrations before blowing attic insulation.

**Air Sealing Value**  
Air infiltration accounts for 25-40% of Ontario home heat loss. Spray foam creates an air barrier that batts and blown insulation cannot match. Air sealing at rim joists and top plates is one of the highest-return energy upgrades available to Ontario homeowners.

**Costs in Ontario 2026**  
Rim joists full perimeter: $800-$2,500. Attic air sealing at penetrations: $1,500-$4,000. Cathedral ceiling full spray: $4-$8/sq ft. Closed-cell wall application: $3-$6/sq ft.

**Safety**  
24-hour re-occupancy period required after application. All spray foam must be covered by drywall or fire-rated thermal barrier in finished spaces per Ontario Building Code.

Find spray foam contractors and discuss insulation strategies at home.renovation.reviews.