Garage Insulation

The garage is an unconditioned space and doesn't need to be thoroughly insulated. However, to keep the rest of your home comfortable and energy efficient, you need to insulate the wall (or walls) that separate the garage from the rest of the house — whether you cover them with drywall or leave them unfinished.

You insulate them as you would any exterior wall, with insulation that includes a vapour retarder. Before installing, clear the area inside your garage of any obstacles.

An Attached Garage Affects the Whole House

An uninsulated attached garage is a large cold surface bolted to the side of a heated building, and the rooms next to it and above it feel the difference. The ceiling between the garage and any living space above is the highest priority, followed by the shared wall with the house.

• Garage ceiling below bedrooms or living space
• The wall shared with the heated part of the house
• The rim joist above the garage door header
• Around the garage door frame and man door
• The attic space above a detached garage

Making a Garage Usable Year-Round

If you want the garage as a workshop, gym or storage that will not freeze, the whole envelope needs treating rather than just the shared surfaces. Closed-cell foam works well because it adds R-value in a shallow depth, which keeps the walls thin, and it will not absorb the moisture that comes off vehicles in winter.

Air Quality Matters Here

Sealing the ceiling and shared wall also reduces the migration of exhaust fumes, solvent vapours and dust from the garage into the house, which is a health consideration as much as a comfort one.