The room over the garage is the coldest room in most newer houses, and around Sundre it has a second problem that owners rarely connect to the first. The garage underneath it is not a garage. It is where a side-by-side, a sled, a quad or a horse trailer gets parked after a day out west of town, and all of that arrives loaded with snow and wet mud. The bonus room sits directly on top of a space that is both cold and extremely humid, and the floor between them was built to do neither job.
Two things are crossing that floor, not one
A normal bonus room floor assembly loses heat downward into an unheated garage. That is the complaint people report: cold feet, and a room that never holds a setting. What is also happening in a garage used as a thaw bay is that a machine covered in snow brings in many litres of water and releases it all as the ice melts. The air in that garage reaches high humidity for hours, and the nearest cold surface is the underside of the floor sheathing above it, on the far side of a batt that was friction-fitted into the joists and has sagged away from the subfloor.
Moist air that reaches that gap condenses on the sheathing. Done repeatedly over a winter, that is how a bonus room floor develops a musty smell and how the subfloor around the edges softens. It is not a plumbing leak and it is not the roof. It is the garage breathing into the floor.
Why batt in that floor cannot hold the line
Batt relies on being in continuous contact with the surface it protects and on nothing moving through it. In a garage ceiling it gets neither. Every penetration for wiring, every light box, the gaps at the ends of the joists and the space around the duct run are all open paths. The insulation is held up by friction and by whatever was stapled under it, and over a few years of door slams and vibration it drops. Closed-cell foam sprayed to the underside of the subfloor bonds to the sheathing and the sides of the joists, so there is no gap for air to reach, and above roughly two inches it is a vapour barrier, which stops the garage's humid air from getting at the wood at all.
The five surfaces the room actually has
A bonus room is enclosed on more sides than a normal bedroom. It has the floor over the garage, two knee walls with unconditioned triangles behind them, the sloped sections above those, and a flat ceiling with attic over it. Six surfaces in some houses. If a crew treats only the sloped ceiling the room will still disappoint, because the triangles behind the knee walls are open to the attic and the cold sits in them at the same height as your ankles. Treating those triangles as part of the envelope, rather than as attic, is most of the fix.
The gable end and the valley wind
These rooms usually have a gable wall with a window in it, and on the acreage builds around Sundre that wall often faces across open ground. Wind on that wall pressurises every gap in it, and in the floor-to-wall joint at the knee wall there are plenty. Sprayed foam at those joints does what no cut-to-size material can, which is fill the irregular gap where three framing members meet.
Who you are dealing with
Bonus room spray foam insulation Sundre gets handled by us from the walk-through onward. We quote and manage it, and our own installers apply the foam.
Bonus Room Spray Foam Insulation Sundre: Common Questions
The room smells musty but there is no leak. Why? Look at what happens in the garage below. Machines thawing out release a lot of water, and the underside of the floor above is the cold surface it finds.
Does the garage need to be heated to fix this? No, and heating it can make the moisture worse by raising how much water the air can carry. Sealing the floor assembly is the move.
Is the sloped ceiling the main problem? It is one of several. The floor over the garage and the spaces behind the knee walls usually matter more, and they are the ones most often skipped.
How much does bonus room spray foam insulation cost in Sundre? It follows the surface area treated and the depth each assembly needs, and access is the other driver, since reaching the knee wall triangles sometimes means opening a small section of finish.
How do I choose a bonus room spray foam contractor in Sundre? Ask them to list every surface they are treating. If the list does not include the floor over the garage and the knee wall spaces, the room will still be cold when they leave.
Size each assembly with the R-value calculator, then get a free Sundre quote. More on Bonus Room Spray Foam Insulation Alberta province-wide.