A pre-engineered steel building is an efficient structure and a difficult envelope, and the reason is the same in both cases: the frame is continuous metal. Metal building spray foam insulation in Athabasca is work on shops, service bays and storage buildings that were put up because steel goes up fast and spans wide, and whose insulation was specified as an afterthought with a roll of blanket under the sheet. On the boreal edge that assembly tells on itself within a couple of winters.
The blanket under the sheet is crushed where it matters
The standard arrangement is fibreglass blanket laid over the purlins and girts and then compressed by the cladding screwed down on top of it. Wherever the blanket passes over a structural member it is squeezed to a fraction of its thickness, so the insulation is thinnest precisely where the steel is, which is where the heat is leaving. The frame is a continuous conductor from the inside of the building to the outside, the insulation is at its worst along that path, and the result is a grid of cold lines across the inside of the building.
The fasteners draw you a map of the problem
On a cold morning in a building like this, look at the inside of the cladding. There will be a line of frost or a row of damp spots at every screw, and the frost will trace the purlins and girts exactly. That is not condensation that happened to land there. It is the pattern of the thermal bridges made visible, and it is the clearest demonstration available that the problem is the structure rather than the quantity of insulation.
Why foam in contact with the sheet changes the result
Closed-cell applied directly to the inside of the cladding and over the structural members does two things that the blanket cannot. It passes over the purlins and girts, so the bridge is covered rather than squeezed around, and it bonds to the steel so there is no air space where moisture can reach a cold surface. At roughly R-6 to R-7 per inch it also puts real R-value into a building that has very little depth available, and at about two inches it is its own vapour control, which on a steel building is exactly where it needs to be.
Preparation decides whether it lasts
Foam bonds to clean, dry, sound steel. On a working building that means the inside of the cladding has to be cleared, washed where it has oil or dust on it, and any active corrosion dealt with rather than buried. Spraying over rust does not stop rust, it only makes it something nobody will see again. On an older shop this preparation is a meaningful part of the day and it is the part that decides whether the job is still bonded in ten years.
Substrate temperature is not negotiable
Steel in an unheated building sits at outdoor temperature, and foam will not bond or yield properly on cold substrate. In practice that means a winter job on a metal building needs temporary heat and enough time for the steel to come up, not just the air. Sheet steel warms quickly once the building is tempered, which is one of the few things that makes winter work on these buildings realistic, but it has to be planned rather than hoped for.
Doors, and what the building is being asked to hold
Most of these buildings have at least one large overhead door, and on a shop it gets used. That sets a practical limit on what temperature can be held and how quickly the building recovers after a door cycle. Deciding whether the target is a working temperature or simply above freezing changes the thickness, and in a building with a big door opening regularly, the recovery rate usually matters more to the people in it than the steady-state number.
Who you are dealing with
For metal building spray foam insulation Athabasca, 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 Athabasca: Common Questions
Why is there frost in lines across the inside of our shop? Those lines are the purlins and girts. The steel bridges straight through and the blanket is crushed thinnest exactly where they are.
Can we add more blanket instead? It will not address the bridge, because the extra material still gets compressed at the same places. Covering the steel is what changes the result.
Does the inside of the cladding need cleaning first? Yes. Foam bonds to clean dry steel, and rust or oil left in place is what causes a bond to fail later.
How much does metal building spray foam insulation cost in Athabasca? It follows the wall and roof area and the thickness chosen, with preparation and, in winter, temporary heat as real additional lines. Clearing the building before the crew arrives keeps both of those down.
How do I choose a metal building spray foam contractor in Athabasca? Ask how they are dealing with the purlins and girts and what preparation is included. If the answer does not mention the structure, the quote is for an area and not an envelope.
Size the assembly with the R-value calculator, then get a free Athabasca quote. More on Metal Building Spray Foam Insulation Alberta province-wide.