Bonus Room Spray Foam Insulation Alberta

Why the bonus room fails

A normal upstairs room has heated space below it. The bonus room has an unheated garage below it, which means it is exposed on five of its six surfaces: the floor, two side walls, the ceiling, and the end wall.

That alone would be difficult. Three things make it worse.

The floor cantilevers. The bonus room floor typically extends past the garage wall, so part of the floor has outdoor air directly beneath it.

The garage is a cold sink. It is unheated, its big door opens repeatedly, and a car brings snow in. The space under the room is effectively outdoors with a roof.

The duct run is the longest in the house. The supply reaching the bonus room has travelled further than any other, often through unconditioned space, arriving with the least air and the lowest temperature of any register in the building.

The floor is where the job is

Insulation put between the floor joists as batt is nearly always what is there now, and nearly always the problem: it sags, it leaves gaps at the ends of the bays, and it does nothing about air moving through the assembly from the garage and from the cantilever.

Closed-cell sprayed into the floor bays, sealed at the cantilever and carried to the perimeter, is the fix. It is an air barrier and insulation in one, and it does not fall down.

Then the knee walls and the sloped ceiling

Bonus rooms usually sit inside the roof structure, which gives them short knee walls with attic space behind them and sloped ceilings above.

Those triangular attic pockets behind the knee walls are unconditioned and connected to the outdoors. Insulating the knee wall itself while leaving the pocket unsealed leaves an air path around it. The reliable approach is to bring the whole assembly inside the envelope by foaming the roof deck, which removes the pockets from the equation.

Do the envelope before the mechanical

The common sequence is backwards: people add a booster fan, a zone damper or a bigger register first, then wonder why the room is still cold.

A leaky, poorly insulated room cannot be fixed by pushing more air at it. Seal and insulate first, then rebalance - and often the rebalancing turns out to be unnecessary.

Bonus Room Spray Foam Insulation Alberta: Common Questions

Do I have to open the garage ceiling? Usually. The floor bays have to be accessible to spray them, and the garage ceiling is normally the access. That is drywall work to plan into the job.

Will insulating the garage itself fix the room? It helps, but the floor assembly is still the boundary and still needs to work. See garage insulation - the two jobs are often done together for one mobilisation.

Is the cantilever really that important? It is the part most often missed and one of the worst. A section of floor with nothing but outdoor air under it, in an Alberta January, is exactly where a cold floor comes from.

How thick? Commonly three inches or more of closed-cell in the floor bays, and more in the roof assembly. The site visit sets it.

Get the room fixed

Get a free quote and describe what the room does in winter and in summer - the pattern tells us where the loss is. See garages, ceilings and attics.