A lower-density spray foam that expands to fill cavities and gaps. It is often considered for interior applications where a softer, more flexible foam makes sense.
Open-cell spray foam is the lower-density of the two spray polyurethane foam types. Because its cells are open rather than sealed, the cured foam is softer and more flexible than closed-cell foam, and it has a spongier feel if you press on it.
Open-cell foam expands considerably as it is applied. That expansion is useful: it lets the foam reach into corners, around wiring and plumbing penetrations, and into irregular framing bays that a batt would bridge over. It is usually applied at a greater thickness than closed-cell foam because it provides less insulating value per inch.
The trade-off is that open-cell foam is more vapor-permeable. That is not a flaw — in some assemblies it is exactly what you want, because it lets the assembly dry. In others, a more vapor-restrictive material is the better fit. That is the kind of decision we work through with you rather than defaulting to one product.
Open-cell foam is not the right answer for every cavity. Before recommending it, we consider:
If you are weighing the two options, here is how they generally differ. Neither is better across the board — they suit different applications. You can read the full breakdown on the spray foam insulation overview.
Tell us about the building and we will walk through whether open-cell foam is the right fit — or whether a different approach makes more sense.
Not sure which foam type fits? Compare spray foam options or view our service area.