The steel buildings along Innisfail's highway frontage span several generations of construction, and the older ones were built in the through-fastened way: panels screwed directly to the purlins and girts, with the screw head on the outside and the shank passing through the panel, the insulation if any, and into the steel behind. That one detail explains most of what goes wrong in these buildings.
Every fastener is a short circuit
A steel screw passing from the outdoor face to the structural steel inside is a direct conductive path with no break in it. In cold weather the inside end of that screw sits at close to outdoor temperature, which puts a cold spot on the inside surface at every fastener. There are thousands of them. Each becomes a condensation site as soon as the indoor air carries any humidity, and the water that forms sits in the small annular gap around the shank. The rust ring that appears around each screw head on the inside face is not a leak from outside. It is the building condensing on its own fasteners.
Blanket insulation makes it worse before it fails
The common original assembly was a fibreglass blanket laid over the purlins and the panel screwed down through it. Compressed to nothing at every purlin, that blanket has an actual installed performance far below its label, and the facing is punctured at every screw. Over time it sags between the purlins, absorbs the condensation forming on the steel, and ends up as a wet suspended layer that holds moisture against the panel. What a crew finds when they take it down is usually a stained, flattened mat and a line of corrosion along every purlin.
Foam adhered to the panel removes the condensing surface
Closed-cell foam sprayed to the inside face of the panels and over the flanges of the purlins and girts does three things in one pass. It raises the inside surface temperature of the steel above the dew point, so there is nothing for the indoor air to condense on. It seals every lap and every fastener penetration, so air stops moving through the shell. And at roughly two inches it is its own vapour barrier, so no separate sheet has to be detailed around all that structure. It also covers the inside end of each screw, which is the detail that stops the rust rings.
The frame still conducts, and that has to be accepted
Spraying over the inside flange of a purlin reduces the loss through it substantially but does not eliminate it, because the web of the member still runs from the cold panel to the warm interior. This is worth saying plainly rather than discovering afterwards. A sprayed building performs very well compared with a blanketed one, and it will still show a faint thermal pattern along the structural lines. Anyone claiming a through-fastened steel building can be made free of that is overselling.
Wet snow sliding off a steel roof
A steel roof sheds snow in slabs rather than letting it melt in place, and in this climate those slabs are heavy and wet. They land against the base of the wall and build a drift that stays there until spring, in contact with the bottom of the cladding and the base trim. Detailing the bottom edge of the wall and the grade under the drip line is part of doing one of these buildings properly, and it is the part that gets left off a quote written from a drawing.
Metal Building Spray Foam Insulation Innisfail: The covering requirement
Foam does not stay exposed in a building people work in. A thermal barrier goes over it, commonly a sprayed coating or a sheet lining, and where there is a flued heater the clearances are settled before anything is applied.
Who you are dealing with
For metal building spray foam insulation Innisfail, we quote and manage the whole job and our own installers do the work. The free quote comes from the people who will be on site.
Metal Building Spray Foam Insulation Innisfail: Common Questions
Why is there rust around every screw on the inside? Because the screw conducts outdoor cold through to the inside face and the indoor air condenses on it. The water sits in the gap around the shank and corrodes from there.
Our building has blanket insulation already. Does it come out? Generally yes. By this stage it is compressed, sagging and holding moisture against the panel, and foam needs a sound surface to bond to.
Will spraying it stop the thermal bridging through the frame? It reduces it a great deal and does not remove it. The web of each member still runs from the cold panel to the warm interior.
How much does metal building spray foam insulation cost in Innisfail? It is priced per board foot of sprayed area at the specified thickness, so the number follows the surface area and the target R-value. Removing failed blanket insulation and the thermal barrier over the foam are separate items.
How do I choose a metal building spray foam contractor in Innisfail? Ask what they will do about the inside end of the fasteners and whether the old blanket is coming out. Both answers tell you whether they have worked on a through-fastened building.
Size the assembly with the R-value calculator, then get a free Innisfail quote. More on Metal Building Spray Foam Insulation Alberta province-wide.