Attic spray foam insulation in Stony Plain has to start with a question that does not arise in the town next door: which era the house belongs to. About 35% of homes here predate 1991, so a third of the attics in this town are nothing like the other two thirds.
Three eras under one town, and they need opposite things
The oldest stock has a low attic over a small footprint, insulation added in layers by successive owners, and a ceiling plane full of holes cut by every renovation. The middle stock, from the seventies and eighties, has a specified depth over a ceiling nobody sealed. The newest has trusses, blown fill to a number, and its losses concentrated at the eave and the penetrations. Advice written for this area generally assumes the third of those, because the town next door is almost entirely that, and it is wrong for a third of the houses in Stony Plain.
What the depth actually is, rather than what it looks like
On any house here that has been added to more than once, the depth across the attic is not uniform and the number quoted by whoever last topped it up is an average and usually a generous one. Insulation settles, gets walked on, gets pushed aside for a cable run, and gets pulled back for a bathroom fan. Measuring in several places rather than one, and looking at what is underneath the top layer, is the difference between a real assessment and a guess. It is also frequently how a household discovers that the top-up they paid for is sitting on something that stopped working years ago.
Every renovation left a hole and nobody closed one
This is the defining condition of the older stock here. A bathroom fan, a range hood, a light fixture, a stack for a suite, a chimney that has been decommissioned and left in place. Each of those was cut through the ceiling by a trade doing their own job, none of them were sealed as part of the ceiling plane, and together they move more air than the insulation is holding back. Dealing with them is a smaller and cheaper job than anything involving depth and it is the one that changes how the house behaves.
Keeping the eave working after the plane is sealed
Sealing a ceiling changes the attic above it, and the part that has to keep working is the airflow from the eave. On the older low attics here there is very little room at the perimeter to begin with, and on any house where insulation has been blown in without baffles the eave is frequently already blocked. That gets established and corrected as part of the work rather than afterwards, because a sealed ceiling under a blocked attic is a worse assembly than the one it replaced.
Attic Spray Foam Insulation Stony Plain: Common Questions
Why did topping it up a few years ago not hold? Worth checking what it was topped up over. Depth on top of a leaking plane does very little.
Which era is our house? The build year decides it, and it changes the whole list. It is the first question asked.
Do we need to do anything about the vents? Usually yes. On the older low attics here the eave is often blocked already.
Size the assembly with the R-value calculator, then get a free Stony Plain quote. More on Attic Spray Foam Insulation Alberta.