Closed-cell and open-cell
Spray foam insulation
The product that seals as it insulates, installed while the cavity is still open and visible.
Two foams, and why the split matters more than the brand
Closed-cell cures dense and rigid. It is rated around R-7.0 per inch, which is the most performance you will get out of a shallow bay, and its density is what makes it water resistant, structurally stiffening and its own vapour barrier in one pass. Open-cell is the soft one. It expands much further, which is what you want in awkward framing and hard-to-reach cavities, it forms an air barrier at three and a half inches, it damps sound noticeably better, and it costs less across a large area. Most buildings want some of each, and the split is decided by the assembly rather than by preference.
What decides it in your building
Available depth, moisture exposure, and how square the framing actually is. A shallow rafter bay with an ambitious target is a closed-cell problem. A cathedral ceiling in an old house that was never true is an expansion problem. Rim joists and anything near grade lean closed-cell for the water behaviour. None of that can be settled from a floor area over the phone, which is why the assessment happens on site and costs nothing.
Seventeen years of it, across Albany County, the Hudson Valley and Berkshire County. Ray runs the assessments himself.
