Spray Foam Insulation: Open Cell vs. Closed Cell. What’s the difference? 8

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.

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 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.

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.

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

The top is a sample of open cell spray foam insulation. The bottom is closed cell spray foam insulation

TOP: Open Cell Spray Foam Insu­la­tion
BOTTOM: Closed Cell Spray Foam Insulation

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8 thoughts on “Spray Foam Insulation: Open Cell vs. Closed Cell. What’s the difference?

  • neal bowman

    We were won­der­ing approx­i­mately how much it would cost to do a steel build­ing. Its our garage that mea­sures 24 x 36 with 10 foot side walls. We would want to have time to save up for some­thing like this. It is all metal studs. thanks

    • Jen Bulfer Post author

      Neal, Just call the office toll free at 855–612-8038. Esti­mates are free. Then you’ll have an esti­mate when you are ready.

    • Jen Bulfer Post author

      In north­ern cli­mates, def­i­nitely closed cell…but be care­ful how it is installed. Don’t let your installer spray it directly to the bot­tom side of the roof to cre­ate a “hot deck”. In metal roofs, this can make them noisy. Keep some air flow between the insu­la­tion and the roof deck. How­ever, in some instances there isn’t enough room in the truss. An on-site visit by your installer is ideal. They can walk you through your options.

  • EcoInsulation

    It should also be men­tioned that this type of insu­la­tion, when installed prop­erly, never needs replac­ing. That can­not be said of fiber­glass or batt insu­la­tion when, once they get wet, lose their insu­lat­ing abil­ity and need to be replaced.