Metal building spray foam insulation in St. Paul is the newest layer of a long building history. On farms and service yards around this town the steel structure is typically the most recent thing put up, standing alongside buildings two and three generations older, and it arrived with a factory insulation package rather than with nothing. So this job is rarely insulating bare steel. It is deciding what to do about the blanket that is already there.
The fibreglass blanket, ten years on
The standard package is a faced fibreglass blanket laid over the purlins and girts and pinched by the sheeting as it is screwed down. It performs on paper and it has two predictable problems in service. The facing gets torn, by fasteners, by equipment, by birds, and once it is torn the vapour control is gone. And the blanket is compressed to nothing at every purlin and girt, so the actual installed R-value is well below the number on the package, with a cold stripe at every structural member.
What condenses, and where
Steel has essentially no thermal mass and goes to outdoor temperature the moment it is exposed to it. Inside a heated building, any moist air that reaches the underside of that steel gives up its water immediately. In this part of Alberta the cold is sustained for months with no reliable thaw in the middle of it, so what forms on the inside of the sheeting freezes and accumulates rather than dripping and drying. The result is a building that appears to leak every spring and a row of rust lines along the purlins. Closed-cell foam sprayed to the underside of the sheeting removes the cold surface entirely: at about two inches it is its own vapour barrier, and because it adheres there is no gap behind it for air to carry moisture into.
Over the blanket, or instead of it
Spraying foam over an intact facing creates a second low-permeability layer with fibreglass trapped between, and in a climate with no winter drying period that pocket stays wet. The normal answer is removal, and it is honest work that belongs on the quote as its own line rather than appearing as a change order. Where the blanket is in good condition and the building is unheated and staying that way, leaving it alone is also a legitimate answer.
Thermal bridging through the frame
Every purlin, girt, column and base plate in a steel building is a continuous metal path from inside to outside. Insulating between members leaves all of those paths open, which is why metal buildings insulated that way still show frost patterns tracing the frame. Foam applied as a continuous layer over the members, rather than only in the spaces between them, is what interrupts the bridge. Around overhead doors, the jamb framing is the worst of them and the detail that gets skipped most often.
Doors, fasteners and the slab edge
The overhead doors and their surrounds deserve to be itemised, because on a steel shop they are where recovery time is lost after a vehicle comes in or out. Exposed fastener penetrations through the sheeting are individually trivial and collectively a real air path. And the slab edge sits against ground that stays frozen for months here, so if the building is being heated through the winter the perimeter is worth addressing while there is a crew on site.
One company, start to finish
We take care of metal building spray foam insulation St. Paul end to end -- the assessment, the quote, the scheduling and the spraying. Our crews do the work.
Metal Building Spray Foam Insulation St. Paul: Common Questions
Can foam go over the existing fibreglass blanket? Generally no. That traps the fibreglass between two low-permeability layers with no way to dry in this climate. The blanket normally comes out first.
Why does the inside of the roof drip? Because steel reaches outdoor temperature instantly and indoor moisture condenses on it. Through winter it freezes and builds up, then releases when the weather warms.
Will insulating between the purlins be enough? No. The purlins and girts themselves are the cold paths, so the insulation has to run continuously over them rather than only between them.
How much does metal building spray foam insulation cost in St. Paul? It follows sprayed area and thickness, with removal of the existing blanket priced separately. Door surrounds and any required protective finish over the foam are their own items.
How do I choose a metal building spray foam contractor in St. Paul? Ask what happens to the blanket and how the purlins get covered. Those two answers separate a crew that has insulated steel from one that has only insulated houses.
Size the assembly with the R-value calculator, then get a free St. Paul quote. More on Metal Building Spray Foam Insulation Alberta province-wide.