Wall spray foam insulation in St. Paul is the most consequential retrofit on an older house and the one that most needs a look inside first. About 73% of the homes here were built before 1991, and walls from that period come in several varieties: a shallow two-by-four cavity with fibre batt, a cavity with loose fill that has settled and left the top foot empty, a wall with no insulation at all behind board sheathing, and a wall that was upgraded during a re-siding with an exterior layer added over the old sheathing. The right plan depends entirely on which one you have.
Opening one cavity changes the whole conversation
A small inspection opening tells us the framing depth, what is in the cavity, whether there is a vapour retarder and which side it is on, whether the sheathing is boards or sheet, and whether anything is damp. All five change the recommendation. The common and avoidable mistake is spraying into a cavity that already has a low-permeability layer on the inside face: that produces an assembly sealed on both sides, and in a climate where the cold is continuous for months with no mid-winter thaw, nothing in that cavity will ever dry. We would rather cut one hole than guess.
Where walls sit in the priority list
Below the rim joist and below the ceiling plane, on nearly every house in this town. Walls lose a lot in total because they are the largest area, but they lose it slowly and by conduction, while the ceiling and the rim joist lose it quickly and by air movement. The exception is the wall that was an exterior wall and is now interior, inside an addition or a bumped-out room: that one has cold on the other side of it and is usually bare, so it behaves like an exterior wall that nobody has ever insulated.
Doing walls from the inside
If the drywall or plaster is coming off for other reasons, that is the moment. The cavity gets cleared of whatever has settled in it, closed-cell foam is sprayed to the back of the sheathing, and at roughly R-6 to R-7 per inch a shallow older cavity reaches a respectable number. At about two inches the foam is the vapour control layer, so the old poly comes out and no new poly goes in. The framing itself still bridges the assembly, which is why an exterior upgrade is the better technical answer when it is available.
Doing walls from the outside, when the siding is coming off anyway
Re-siding is the best opportunity an older house gets. With the old cladding off, a continuous exterior layer can be added over the sheathing, which covers the framing as well as the cavities and is the only way to deal with thermal bridging through every stud. For a house in this town that is overdue for siding, the sensible sequence is to treat the insulation and the siding as one project rather than two, and it is worth planning even if the siding is a year or two away.
Drill-and-fill, and being straight about it
Injecting foam into a closed cavity through small holes is sometimes offered. It can work on an empty cavity with clear access, and it has real limits: you cannot see where the material went, the cavity may be obstructed by blocking or wiring, and if there is settled fibre in there the foam goes around it rather than replacing it. We will say when a wall is a candidate and when it is not, because the failure is invisible, and an invisible failure in a wall that cannot dry is the worst outcome available on this stock.
Who you are dealing with
For wall spray foam insulation St. Paul, 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.
Wall Spray Foam Insulation St. Paul: Common Questions
Can you insulate our walls without removing the drywall? Sometimes, on an empty and unobstructed cavity. Where there is settled fibre or an existing vapour retarder, opening up is the only way to get a sound assembly.
Should walls come before the attic? Rarely. The ceiling plane and the rim joist lose heat faster and cost less to fix, so they come first unless a wall is already open.
We are re-siding next year. Does that matter? A great deal. With the cladding off, insulation can go on continuously over the framing, which is the only way to address the thermal bridging through the studs.
How much does wall spray foam insulation cost in St. Paul? It follows the sprayed area and the cavity depth, with removal of existing material and any drywall work as separate items. An inspection opening before the quote is what keeps that number honest.
How do I choose a wall spray foam contractor in St. Paul? Ask them what they found when they opened a cavity. If nobody opened one, the quote is based on assumptions about a wall built sixty years ago.
Size the assembly with the R-value calculator, then get a free St. Paul quote. More on Wall Spray Foam Insulation Alberta province-wide.