The steel buildings around Canmore are not farm structures. They are the trades shops, service bays, equipment stores and light industrial units at the working edge of town, plus the maintenance buildings that keep a mountain recreation economy running. The envelope problem in all of them is the same one, and it is driven by the material rather than by the use.
Steel has no tolerance for a temperature difference
A steel panel is thin and highly conductive, so its interior face sits at essentially the outdoor temperature. Put any humid air in the building - a vehicle driving in with snow on it, a wash bay, a kettle, people working - and that air reaches the panel and gives up its water instantly. The result is the drip that gets reported as a roof leak in a building with a perfectly sound roof. It is condensation, it happens on clear cold nights rather than during storms, and that timing is the giveaway.
Why fibre in a steel building goes wrong
The usual retrofit is a blanket laid against the inside of the panels with a facing. Air finds its way behind it at every lap and fastener, hits the cold steel, condenses, and the batt holds the water against the panel. Then the facing sags, the insulation loses whatever value it had, and the steel starts to corrode from the inside out where nobody can inspect it. On the buildings we open here that sequence is at a different stage in each one, but it is always the same sequence.
Closed-cell on the panel removes the condensing surface
Sprayed directly on the inside face of the steel, closed-cell foam adheres - there is no gap behind it for air to reach the panel, so there is no cold surface available to condense on. At about R-6 to R-7 per inch it reaches a useful value within the depth of the purlin, and at roughly two inches it is already the vapour control layer. That is the mechanism, and it is the reason this is the standard specification for steel rather than a preference.
The purlins are the detail that gets skipped
A metal building's frame is a continuous steel path from the inside to the outside. Spray between the purlins only and every one of them remains a thermal bridge: a cold stripe on the ceiling that will frost or drip even when the bays between them are dry. Carrying the foam over the face of the purlin, so the steel is covered rather than merely flanked, is what makes the assembly continuous. It costs more foam and it is the difference between a solved building and a mostly solved one.
Snow load, wind and a tall thin shell
The frame of a steel building in the Bow Valley was engineered for a serious snow load, which is reassuring, but the shell is light and the valley wind drives air through every lap it can find. A tall building in a wind corridor is also running a strong stack pressure, pushing warm air up and out through the ridge details. Sealing the eave, the ridge, the door frames and the base trim is the air sealing half of the job, and on a steel shell it is where the measurable loss is.
Metal Building Spray Foam Insulation Canmore: Common Questions
The roof drips but it is not raining. Is it leaking? Almost certainly not. Humid interior air is condensing on cold steel, which is why it happens on clear cold nights rather than in a storm.
Can we insulate over the existing blanket? Not reliably. If it is holding moisture against the panel it has to come out so the foam can bond to clean steel.
Do the purlins need to be covered? Yes, if you want it fixed. An uncovered purlin stays a cold stripe and will frost regardless of what is between them.
How much does metal building spray foam insulation cost in Canmore? Priced per board foot of sprayed area, so panel area and target depth set the number. Covering the purlins adds foam and is the item worth keeping in scope.
How do I get a metal building spray foam insulation quote in Canmore? Tell us the building footprint, the clear height, and whether there is existing insulation in there. Height drives access as much as area does.
Size the assembly with the R-value calculator, then get a free Canmore quote. More on Metal Building Spray Foam Insulation Alberta province-wide.