One of the most common questions we get is “What’s the difference between open cell and closed cell spray foam insulation?”
The difference is in the structure of the cells.
THE STRUCTURE OF THE CELLS
Both closed cell and open cell spray foams consist of tiny, microscopic cells grouped together to create insulation. The cells in open cell spray foam remain open. With closed cell spray foam, the cells are closed.
OPEN CELL AND CLOSED CELL SIMILARITIES
Open cell and closed cell spray foams share some great features. Most importantly, they both provide a high R-value. They both also air-seal the building envelope by eliminating gaps and voids that batts may miss. Open cell and closed cell spray foams are installed in a similar manner, using the same equipment. The two products, however, have a few differences.
OPEN CELL SPRAY FOAM INSULATION
The open cell structure of open cell spray foam creates an insulation that is soft, much like the consistency of a marshmallow. The open cell structure makes this insulation a good choice for southern climates. The open cells also allow moisture to permeate the insulation. It is not recommended that this insulation be used below grade, or in any instance that it may come into contact with moisture. A vapor barrier is required.
CLOSED CELL SPRAY FOAM INSULATION
The closed cell structure of closed cell spray foam creates an insulation that is strong and rigid, adding strength to the building structure. Closed cell spray foam’s most important feature is that this insulation is a vapor barrier: moisture cannot travel through the closed cells. An additional vapor barrier, usually a layer of plastic is not necessary when insulating with closed cell spray foam.
Spray foam insulation is most commonly priced by the board foot. A representative will read your plans or come to your project and measure how many board feet of spray foam you will require.
When comparing the price of open cell vs. closed cell spray foam, be sure to keep in mind that you will have an additional cost of a installing a vapor barrier with open cell spray foam. Many times the prices are similar once the vapor barrier is figured in.
by Jenny Bulfer