A bonus room is the room that nobody can get comfortable. In Stettler it takes two forms: the modern room built over an attached garage, and in the older part of town the upstairs space above a lean-to or a later addition. They fail for the same reason, and on an exposed prairie lot they fail harder than they would in a sheltered subdivision in a city.
A floor is not a wall
The floor of a bonus room over a garage has heated room above it and unheated garage below. That makes it part of the building envelope, and it is almost never built like one. The joist cavities run from one exterior wall straight through to the other, open at the ends, so outdoor air entering at the rim or at a soffit travels the length of the floor underneath the finished room. Batt stapled up between the joists does nothing about that because the air is moving through and around it rather than being stopped by it.
Three exposed sides at once
The geometry is the problem. A room over a garage typically has exterior wall on three sides, a ceiling into attic above, and an unheated space below. Five of its six surfaces face something cold, where an ordinary bedroom has one or two. On a lot with open field upwind, the wind pressure on that assembly is sustained rather than occasional, and the floor becomes the single biggest contributor.
What the fix actually is
Closed-cell foam sprayed to the underside of the floor deck from inside the garage, carried out to the perimeter and sealed at the rim and the ends of every joist bay. That closes the air path, which is the thing that was never closed, and adds roughly R-6 to R-7 per inch while it is at it. The same pass should pick up the garage ceiling plane and the wall between the garage and the house, because those leak too.
Then the knee walls and the slopes
If the room has sloped ceilings, there are knee wall cavities behind the short vertical walls at either side. Those cavities are usually vented attic space with nothing but a batt leaning against the back of the drywall, so the room loses heat sideways into cold air. Sealing and insulating the knee wall back and the sloped section is often what finally makes the room usable.
The older-house version
Above a lean-to addition or a single-storey wing, the upstairs room has the same problem for a different reason: the floor was built as an interior floor and the space under it was never conditioned. The diagnosis is identical. Find out what is below the floor and whether outdoor air can reach the joist cavities, and treat the floor as the envelope surface it has become.
Who quotes it and who sprays it
We do bonus room spray foam insulation Stettler ourselves. We scope and quote it, we book it, and our own installers spray it -- one company, one point of contact.
Bonus Room Spray Foam Insulation Stettler: Common Questions
Why is the room over the garage always the coldest? Because five of its six surfaces face unheated space, and the floor cavity is usually open to outdoor air at the ends.
There is already insulation in the garage ceiling. Why is it still cold? Insulation does not stop air movement. If the joist bays are open at the rim, outdoor air is travelling under the room regardless of what is in the cavity.
Do the sloped ceilings need doing as well? Usually yes. The knee wall cavities beside the room are vented attic, and heat leaves sideways through them.
How much does bonus room spray foam insulation cost in Stettler? It is priced per board foot over the sprayed area, so the floor deck, the knee walls and the sloped ceiling each add surface. Access decides a lot of it, since spraying the floor from below in the garage is straightforward and reaching a slope from inside the finished room is not.
How do I choose a bonus room spray foam contractor in Stettler? Ask whether the quote includes the ends of the joist bays at the rim. That detail is the air path, and a quote that only lists the flat underside of the floor is missing it.
Size the assembly with the R-value calculator, then get a free Stettler quote. More on Bonus Room Spray Foam Insulation Alberta province-wide.