A flat ceiling with a ventilated attic over it is a forgiving assembly. A sloped or vaulted ceiling is not, because there is no buffer space between the drywall and the roof deck, and the entire thermal and moisture job has to happen inside the depth of a rafter. Ceiling spray foam insulation in Slave Lake is mostly about that second kind, and this town has more of them than its size suggests.
Why there are so many vaulted ceilings here
A house built with a view of the water tends to be designed around the room that has the view, and that room usually gets a raised or cathedral ceiling. The newer part of the town's housing stock, built from 2011 onward, carries that layout frequently: an open great room with a sloped ceiling on the lake side and conventional flat ceilings over the bedrooms. The owner then discovers that the one room the house was designed around is the hardest room in it to keep warm.
What goes wrong inside a rafter cavity
The intended design is batt in the cavity with a continuous air channel above it running from the eave to the ridge. It depends on three things being true at once: the batt fully filling its width, the channel staying open along its whole length, and the drywall below being airtight. In practice one of them usually is not. Batt gets compressed by wiring or a light box, the channel gets blocked where the roof planes meet, and the interior air barrier is interrupted by every fixture in the ceiling. Warm air then reaches the cold deck and condenses or frosts there, inside a cavity that cannot be inspected.
A long winter with no thaw to reset it
Further south, repeated thaws dry an assembly out several times a season. Here the cold arrives and holds, so whatever moisture gets into that cavity in November is still in it in March, accumulating. By spring break-up it is enough liquid water to stain a ceiling, and the first assumption is always a roof leak. On a sloped ceiling the probability that it is actually interstitial condensation is high.
What closed-cell changes
Sprayed against the underside of the roof deck, closed-cell adheres to the sheathing, so there is no gap above it for air to move through, and at roughly R-6 to R-7 per inch it reaches a usable R-value in the depth a rafter actually has. Past about two inches it is its own vapour retarder, which means the deck is no longer the cold surface where moisture collects. That converts the cavity to an unvented assembly deliberately, as a designed detail, rather than leaving a vented one that has quietly stopped venting.
The details that decide it
Where the sloped ceiling meets a flat one there is a transition with a knee wall, and that is where most of the loss on these rooms actually is. The ridge, the ceiling fixtures and the junction where the vault meets an exterior wall all need the same attention. On lake-side rooms with a large glazed gable we also look at the wall under the glass, because a sustained onshore wind finds the gable framing long before it finds anything else.
Who you are dealing with
For ceiling spray foam insulation Slave Lake, we quote and manage the whole job and our own installers do the work. The free quote comes from the people who will be on site.
Ceiling Spray Foam Insulation Slave Lake: Common Questions
Our vaulted room is the coldest in the house. Is the insulation missing? Usually it is present and either compressed or bypassed by air. The cavity has no spare depth, so small faults have large effects.
Is a stain on a sloped ceiling always a roof leak? No, and here it often is not. Condensation inside the cavity accumulates all winter and shows up as water in spring.
Can you foam it without taking the ceiling down? It depends on access from a gable or from above. Where the drywall has to come down we say so before quoting, because that is most of the difference between two prices.
How much does ceiling spray foam insulation cost in Slave Lake? Priced per board foot over the sloped area at the depth the rafter allows, plus any removal needed to get at it. The knee wall transition is a small separate item that earns its keep.
How do I choose a ceiling spray foam contractor in Slave Lake? Ask whether they are converting the cavity to an unvented assembly on purpose, and what happens at the knee wall. A quote that does not mention either has not looked at the real problem.
Size the assembly with the R-value calculator, then get a free Slave Lake quote. More on Ceiling Spray Foam Insulation Alberta province-wide.