About 76% of homes in Drumheller were built before 1991, and a large share of that is older still: housing put up quickly for mining families between the coal boom that began after 1911 and the decline that followed the Second World War. Attic spray foam insulation in Drumheller is therefore almost never a case of topping up a modern, generously vented attic. It is work on a roof that was not built with a ventilation strategy at all.
A roof with no intake
Soffit vents became standard long after most of this stock went up. Open a coal-era roof here and the usual finding is a shallow heel at the eave, rafters sitting almost on the top plate, and either no soffit opening or an opening that was later buried under loose fill. Exhaust may have been added at the ridge or through a roof cap. The result is a vented roof on paper and a stagnant roof in practice, because air cannot leave a space it cannot enter. Adding another roof vent to a roof with no intake does nothing except pull conditioned air out of the house through the ceiling.
Where the heat is actually going
In these houses the ceiling plane is perforated rather than insufficiently insulated. Chimney chases from a long-dead solid-fuel appliance. Balloon-framed interior walls that were never capped at the top plate, so the wall cavity is open to the attic along its whole length. Light fixtures in plaster, bathroom fans ducted to nowhere, and the stair opening to a half-storey. Warm wet air leaves through those and condenses on the sheathing, and no depth of insulation laid over the top of them intercepts it.
Additions on additions
Drumheller houses have been extended repeatedly, often in the mining years and again after. That produces separate roof planes meeting at odd angles, a cathedral pocket over a lean-to kitchen, and small isolated attics with no access hatch at all. Each of those is its own envelope problem, and the one most commonly missed is the dead triangle where an addition roof meets the original wall. There is almost never insulation in it and there is frequently a direct air path from the house into it.
Why the valley changes the roof
Cold air drains off the prairie above and pools on the valley floor overnight, so the roof on a floor-level house spends still winter nights in the coldest air the town has. At the same time this is semi-arid country with a very wide temperature spread; the record high is 40.6 degrees Celsius from July 1941 and the record low minus 43.9 from January 1996. A roof assembly here has to survive both ends, which is a strong argument for a sealed roof deck over a vented one on the complicated roofs this stock produces.
What foam does up there
Closed-cell applied to the underside of the deck seals the assembly, delivers roughly R-6 to R-7 per inch and acts as its own vapour retarder past about two inches, which is what makes an unvented roof safe where ventilation was never achievable. On the flat parts, the right job is usually sealing every penetration and the top plates with foam and then bringing the depth up with blown-in on top. We quote the job, schedule it and stand behind it, and on this stock the sealing is the half that changes how the house feels.
Attic Spray Foam Insulation Drumheller: Common Questions
Our attic is vented but still sweats. Why? Almost certainly because there is exhaust and no intake. Air cannot leave a space it cannot get into, so the vents move house air up through the ceiling instead.
Can an old roof here be sealed rather than vented? Often it is the better answer. On a roof with a shallow heel and several planes meeting, venting properly is not achievable, and closed-cell on the deck removes the need for it.
Why do we have cold spots over one room? Usually an addition. The pocket where the new roof met the old wall rarely got insulated and usually has an air path into it.
How much does attic spray foam insulation cost in Drumheller? It follows the sprayed area and the target depth, plus any blown-in over the flat. On a 1920s or 1930s house the variable that moves the number most is how many separate attic pockets the additions created.
How do I choose an attic spray foam contractor in Drumheller? Ask what they intend to do about the lack of soffit intake. An answer that involves adding more roof vents is not an answer on this housing stock.
Size the depth with the R-value calculator, then get a free Drumheller quote. More on Attic Spray Foam Insulation Alberta province-wide.