An arch presents a low, curved face to the wind, and in open country west of Cochrane that shape collects snow rather than shedding it. Quonset spray foam insulation in Cochrane is worth planning with that in mind, because drifting changes what the bottom of the building experiences all winter and it is the part of the shell that suffers first.
Drifted snow buries the part that is already the wettest
Everything that condenses inside the arch runs down the curve to the bottom. Everything that drifts outside packs against the same low band from the other side. That band therefore spends months cold and wet on both faces, which is why corrosion on these buildings almost always starts low rather than high. A drift held against steel also keeps that steel at freezing long after the air has warmed, so the inside face stays a condensation surface well into a chinook.
Where the insulation has to reach
Down to the base. Stopping the foam a foot or two above the floor leaves a cold band exactly where the drifting keeps the steel coldest, and that band becomes the new condensation line with water running down behind the material above it. Carrying it low and detailing the termination so nothing can get behind it is what makes the difference on a building that drifts.
Grading and where the snow is allowed to sit
This is not insulation work and we will say so, but it belongs in the conversation. A building where snow is pushed up against the wall every time the yard is cleared will keep doing what it has been doing. Where the drift can be kept off the wall, the low band gets a chance to dry, and everything applied inside lasts longer for it.
The foothills swing works the assembly
Temperatures move fast here and a chinook can put the building through a full freeze and thaw inside a day or two, repeatedly. Anything in the assembly that has taken on moisture gets worked by every one of those cycles. Closed-cell foam does not absorb water and does not lose value after cycling, which is why it holds up on a building that swings rather than sitting cold.
Deal with the steel before covering it
Because the corrosion on these buildings concentrates in the low band, that is exactly where the shell has to be looked at before anything is sprayed. Active rust continues underneath foam and the material does not bond reliably to loose scale, so the areas that most need the insulation are the ones most likely to fail if the preparation is skipped. There are no stud bays or flat planes on an arch, so foam is the only thing that follows the curve without leaving a void - but it only works on clean, sound steel.
Quonset Spray Foam Insulation Cochrane: Common Questions
Why does the bottom of my quonset rust first? It is wet on both sides - condensation running down the curve inside, and drifted snow packed against it outside - and it stays frozen longer than the rest of the shell.
How far down should the foam go? To the base. Stopping partway up leaves a cold band precisely where the drifting keeps the steel coldest.
Does it matter where we push the snow? It does. A drift held against the wall keeps that band cold and wet for months, and clearing it away lets the steel dry.
Estimate the thickness with the R-value calculator, then get a free Cochrane quote. More on Quonset Spray Foam Insulation Alberta province-wide.