How does spray foam compare to batt and rigid board insulation for an Ottawa garage in terms of cost?

Each of the three main insulation types has a different price point and performance profile, and the right choice for your Ottawa garage depends on your budget, how you plan to use the space, and whether you are doing the work yourself or hiring it out.

Fibreglass batt insulation is the most affordable option. For a typical two-car garage in Ottawa with two-by-six walls and an unfinished ceiling, material costs for R-20 batts in the walls and R-32 batts in the ceiling run roughly eight hundred to fourteen hundred dollars. If you hire an insulation contractor, expect to pay between two thousand and four thousand dollars installed, including the vapour barrier. Batt insulation is straightforward for a homeowner to install, and it performs well as long as you achieve a tight fit with no gaps or compression. The downside in Ottawa is that batts alone do not provide an air seal, so you need to be meticulous with your vapour barrier and acoustic sealant at all seams and penetrations. Any gap in the vapour barrier allows warm moist air to reach the cold sheathing, which leads to condensation and eventually mould.

Rigid foam board, typically extruded polystyrene or polyisocyanurate, costs more per square foot but offers some advantages. Material for the same two-car garage runs roughly fifteen hundred to twenty-five hundred dollars depending on the product and thickness. Polyiso gives you about R-6 per inch, while XPS provides about R-5 per inch. Rigid board is excellent for reducing thermal bridging when applied as a continuous layer over the studs before you install drywall. Many Ottawa contractors recommend a hybrid approach where you fill the stud cavities with mineral wool batt and then add a layer of rigid foam on the interior face. Installed by a contractor, this hybrid approach for a two-car garage typically costs four thousand to seven thousand dollars.

Closed-cell spray foam is the premium option and the only one that provides both insulation and a complete air and vapour barrier in a single application. In Ottawa, spray foam contractors typically charge between two and three dollars fifty per square foot per inch of thickness for closed-cell foam. For a two-car garage insulated to R-20 in the walls, that translates to roughly three inches of closed-cell foam at approximately six to ten dollars per square foot of wall area. The total installed cost for walls and ceiling in a standard two-car garage usually lands between eight thousand and fifteen thousand dollars. Open-cell spray foam is cheaper at roughly one dollar to two dollars per square foot per inch, but it does not act as a vapour barrier on its own and has a lower R-value per inch, so it is less ideal for Ottawa garage applications where moisture control is critical.

For most Ottawa homeowners working within a reasonable budget, the hybrid approach of mineral wool batts in the cavities plus a layer of rigid foam board delivers excellent performance at a moderate cost. If budget is the primary concern and you are doing the work yourself, fibreglass batts with a carefully sealed six-mil polyethylene vapour barrier will serve you well. If you want the absolute best performance and are willing to invest, closed-cell spray foam eliminates almost all the installation quality concerns because it expands to fill every gap and crack, which matters enormously in a garage where framing is often less precise than in the house itself.

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