Open & closed cell spray foam insulation

Spray foam starts as two liquids. Our rig heats them and pumps them through a heated hose to the spray gun, where they mix and expand into foam within seconds. It bonds to wood, steel and concrete, and it fills the cracks, seams and odd-shaped cavities that batts and loose-fill leave open.

That is the real advantage over traditional insulation: air sealing and insulation happen in the same pass. Most heat loss in a Minnesota winter comes from air leaking through gaps, not just from thin insulation, and foam closes those gaps as it goes on.

Closed-cell foam is dense and rigid, at roughly 2 pounds per cubic foot, and delivers about R-6 to R-7 per inch, depending on the product. At around 1 to 2 inches (again depending on the product) it also works as a vapor retarder, and it stiffens the walls and roof deck it is sprayed on.

It is our go-to on steel-sided barndominiums and pole buildings, where it stops condensation right at the panel, and anywhere space is tight: rim joists, cathedral ceilings, basement walls and 2x4 walls that need a higher R-value.

Open-cell foam is soft and spongy, at about half a pound per cubic foot, with roughly R-3.5 to R-3.8 per inch. It expands far more than closed cell, so it completely fills deep wall and roof cavities, and it quiets sound between rooms and floors.

It costs less per inch than closed cell, which makes it a good fit for full-depth wood-framed walls and rooflines. In Minnesota it needs a separate vapor retarder on the warm side, such as a vapor retarder primer or membrane, which we plan for in the estimate.

Spray foam earns its cost where airtightness, moisture control or limited space matter most. The most common places we spray:

Spray foam is a foam plastic, and the building code treats it that way. In living space it has to be covered by a thermal barrier, usually half-inch drywall. In attics and crawl spaces entered only for service, an ignition barrier or an approved coating can be used instead. We'll tell you which applies before we start.

Our crew sprays in full-face or supplied-air respirators and protective suits. Plan on keeping everyone out of the building while we spray and for the re-occupancy time on the foam manufacturer's data sheet, typically about 24 hours. Once it has cured, the foam is stable and inert.

We mask windows, door openings, outlets and anything that should stay foam-free, then spray in passes to the depth in your estimate. Open-cell foam is trimmed flush with the studs so drywall goes on flat. When we're done we clean up the shavings and overspray and walk the job with you or your builder.