Most ceiling insulation conversations in Alberta are about keeping heat in. In Medicine Hat a good share of them are about keeping it out. Ceiling spray foam insulation in Medicine Hat is frequently bought because of what a vaulted room does in July, not January.
The deck gets far hotter than the air does
This is one of the sunniest places in Canada. A dark roof surface in full sun sits well above the outdoor air temperature, and the underside of that deck radiates into whatever is beneath it. In a room with a flat ceiling and a deep attic, there is a large buffer between the two. In a vaulted room there are a few inches of insulation and nothing else, so the hot surface is effectively in the room.
Insulation works in both directions, ventilation does not always help
A vent channel is meant to carry heat away, and on a calm hot afternoon it carries very little. Relying on it to manage summer gain in a cathedral ceiling gives up cavity depth for a mechanism that works least well exactly when it is needed most. Filling that depth with material that performs the same in both directions is a better use of the space available.
The daily swing works the assembly
Medicine Hat routinely drops twenty degrees or more overnight. A roof deck that was very hot at five in the afternoon is cool by morning, every day, all summer. That cycling moves fasteners and opens joints over time, and it is another argument for an assembly that is adhered and continuous rather than fitted and mechanically held.
Dry air changes what people notice
Because the air here is dry, the usual winter warning signs are muted - less condensation on glass, fewer damp patches. The result is that a poorly performing ceiling often goes unnoticed until a summer where the room simply cannot be used in the afternoon.
A vaulted ceiling has no room to vent
Without an attic above it there is nowhere for the airflow a conventional assembly depends on, which is why foam applied to the underside of the deck is normally the assembly that works. It is the insulation, the air barrier and the vapour control in one application.
Ceiling Spray Foam Insulation Medicine Hat: Common Questions
Is this a summer problem or a winter problem? Here it is often both, but the complaint that prompts the call is usually summer. A vaulted room under a sunlit deck has very little between the hot surface and the space below.
Does the vent channel deal with summer heat? Not well on a still, hot day, which is when it matters. Giving up cavity depth to it is a poor trade in a shallow assembly.
Why does the daily temperature swing matter? It cycles the roof deck every day rather than every season, working fasteners and joints. A adhered continuous layer handles that better than pieces held in place mechanically.
Work out the depth with the R-value calculator, then get a free Medicine Hat quote. More on Ceiling Spray Foam Insulation Alberta.