Edmonton's older neighbourhoods are laid out on a grid with rear lanes, and that means a very large number of detached garages - a different job from the attached garage that dominates newer suburbs.
Which one you have changes the answer completely.
Detached garages
A detached garage is its own small building. Nothing you do to it affects the house, so the only question is what you want the space to be.
If you want to heat it and work in it, you are insulating a standalone structure with a large door in one wall. Sealing matters more than depth, because a detached garage is typically built more loosely than a house - single-layer sheathing, unsealed penetrations, and a big opening that dumps the air every time it is used.
There is a limit to what insulation can do about the door, and an honest installer will say so. The goal is a building that holds temperature between openings and recovers quickly, not one that never loses heat.
If it is unheated storage, insulating it may not be worth much at all. An unheated garage with no heat source will sit close to outside temperature regardless of what is in the walls. Insulation slows heat transfer; it does not create warmth. We would rather tell you that than sell you a job that will disappoint you.
The exception is if you are heating it occasionally - then you are insulating so it warms up quickly and holds it, which is a real and reasonable goal.
Attached garages
An attached garage is a different problem, because it shares walls and often a ceiling with heated space.
The priority is the shared assemblies, not the exterior walls of the garage:
- The common wall between garage and house.
- The garage ceiling, if there is living space above it.
That second one is the most common complaint in the city: a room above the garage that never warms up. It sits over an unheated space, usually with framing that leaks air on several sides. See bonus room insulation.
There is also a safety dimension. The assembly between a garage and living space is a fire and gas separation, and vehicle exhaust and fuel vapours should not be able to migrate into the house. Sealing that boundary properly is worth doing on those grounds alone, before comfort enters the conversation.
The covering requirement
Foam in a garage generally needs an appropriate thermal barrier over it, and a garage is exactly the kind of space where people skip that because it feels like a utility building.
Get it specified in the quote. See thermal barrier vs ignition barrier.
Edmonton's deep cold
Because Edmonton stays cold rather than swinging, an unheated attached garage sits as a large cold surface against the house for months. If there is a room above it, that is why it is uncomfortable, and it is why the ceiling assembly is usually the highest-value job on the list.
What we do
We are a referral service. We do not install. We connect you with vetted installers - certification, insurance and WCB standing checked.
No price without a site visit. Get a quote, and say whether the garage is attached or detached, and whether you intend to heat it.
See also garage spray foam insulation province-wide.