Quonset spray foam insulation in Olds is sprayed directly onto the inside of the arch. Owners around this town tend to arrive at the conversation having already worked out most of it, which changes what is worth saying.
An owner who already knows why the batt failed
In a district with this much agricultural training and trade in it, a quonset owner has usually already tried something and watched it fail. They have stapled batt to the purlins and seen it sag away within two seasons, or fitted board and found the gaps behind it. They do not need the mechanism explained. What they want to know is whether a sprayed application behaves differently on the same curve, and the honest answer is that it does, because it is applied as a liquid and cures in contact with the sheet rather than being held against it.
The corrugation is the reason, not the curve
It is worth being precise, because the usual explanation is imprecise. The problem is not simply that the building is round. It is that the sheet is corrugated, so anything flat touches only the ridges and leaves a continuous channel behind it running the length of the building. Air moves in those channels and condenses against the cold steel out of sight. Foam fills the corrugation itself, which removes the channel rather than covering it.
The end walls and the bottom edge, which is where it leaks
The arch is usually sound. The end walls are framed conventionally, carry the doors, and have been cut about over decades to fit whatever needed to pass through. The bottom edge, where the sheet turns down to meet a curb or the ground, is a continuous opening running both sides and is hidden behind whatever is stored against the wall. On an Olds quonset both of those matter more than the arch does.
Whether the steel is worth spraying at all
Foam bonds to sound, clean, dry steel and to nothing else. On a building of this age the base of the arch is where corrosion starts, because water sits there and equipment has knocked it over the years. That gets inspected before anything is quoted. Where there is significant corrosion or a sheet that has worked loose, repair comes first, and an honest assessment on one of these occasionally ends with a recommendation not to proceed at all. An owner in this district would rather be told that than be sold something that fails in three years.
Quonset Spray Foam Insulation Olds: Common Questions
Why does batt sag off a quonset roof? That is the normal outcome. Foam cures in contact with the sheet rather than being held against it.
Is it the round shape that causes the problem? The corrugation, more precisely. Flat material touches the ridges and leaves a channel behind it.
Where should we look first? The end walls and the bottom edge. The arch is usually the sound part.
Size the assembly with the R-value calculator, then get a free Olds quote. More on Quonset Spray Foam Insulation Alberta.