About 16 percent of Cochrane homes were built before 1991, so most of this stock is recent, and recent building in the foothills means a lot of vaulted and cathedral ceilings taking advantage of the view. Attic spray foam insulation in Cochrane therefore runs into a situation the word attic does not describe: over a vaulted room there is no attic. There is a rafter cavity a few inches deep with the room on one side and the roof deck on the other.
Why a vaulted ceiling is the hardest part of the house
In a normal attic there is space for as much depth as you want, and air can move through it. Over a vault there is neither. The cavity is shallow, so the insulation value is limited by geometry rather than budget, and if it is vented it needs a clear air channel from the eave to the ridge that the insulation must not block. Get that wrong and the deck condenses in a space nobody can inspect.
The two legitimate assemblies, and the one that fails
A vented cathedral assembly keeps a continuous air channel above the insulation, from soffit to ridge, with no interruptions. An unvented assembly brings the deck into the envelope with closed cell applied directly to its underside, so there is no cold surface and no channel to keep clear. Both work. What fails is the middle: batt stuffed to the full depth of the rafter with the vent path pinched off and no seal, which is what most older vaults actually contain.
The flat parts still follow the ordinary rules
Where the house does have a conventional attic, the order is unchanged and it matters. Seal the penetrations first - top plates, plumbing stack, bathroom fan, ceiling lights, the hatch - then add depth. Insulation slows heat; it does not stop the household air that carries moisture up into the roof space.
Where the two meet is where it leaks
The junction between a vaulted section and a flat attic is a wall inside the roof, and it is very often left open. Warm air travels out of the vault, into the attic, and up. That transition is an awkward, irregular gap, which is exactly what foam is good at and what nothing cut to size will close.
What to say when you enquire
Which rooms are uncomfortable, and whether the ceiling in them is flat or sloped. That one detail decides whether this is a straightforward attic job or a rafter-cavity assembly question, and the two have very different scopes.
Attic Spray Foam Insulation Cochrane: Common Questions
Our vaulted room is always cold - can it be insulated? Yes, but the cavity is shallow, so the assembly matters more than the depth. It is either properly vented from soffit to ridge or properly unvented, never halfway.
Can you just add more in the rafters? That is the version that fails. Filling the cavity without keeping the vent channel clear leaves a cold deck condensing where nobody can see it.
Does the flat attic still need doing? Usually, and the junction between it and the vaulted section is the leak nobody closes.
Size the job with the R-value calculator, then get a free Cochrane quote. More on Attic Spray Foam Insulation Alberta province-wide.