Open-Cell and Closed-Cell Foam: What Is the Difference?
The terms open-cell and closed-cell describe the internal structure of spray foam. Both products expand and can reduce air movement, but their density, firmness and moisture behaviour differ.
Open-cell foam
Open-cell foam is lighter and softer. It can expand significantly, making it useful for filling large wall or roof cavities where sound control and air sealing are priorities.
Closed-cell foam
Closed-cell foam is denser and more rigid. It generally provides a higher insulating value per inch and can add strength to certain assemblies when installed correctly.
Moisture considerations
The right choice depends on climate, assembly design and local building requirements. Foam should not be selected only by price or thickness.
Access and future work
Plumbing, wiring and roof repairs may need access later. Planning these details before installation can prevent unnecessary removal.
Professional assessment
An installer should review the cavity depth, ventilation strategy and surrounding materials before recommending either type.
