How Is Closed-Cell Foam Different From Open-Cell Foam on a Roof?
Closed-cell foam is the roofing kind: its cells stay sealed, it sheds water, and it runs about R-6 per inch at roughly 2 pounds per cubic foot. Open-cell foam is soft and light, about R-3.6 per inch, and belongs inside wall and ceiling cavities.
Press a thumb into cured roofing foam at a parapet edge and it barely gives.







