With the growing popularity of spray foam insulation, we get a lot of questions from clients about it. Here is an overview of this product and some common questions and answers.
There are two distinct types of spray foam insulation: open cell and closed cell. Closed cell spray foam cures into a hard, rigid state whereas open cell cures with a spongy, softer feel to it. In terms of R-values, closed cell spray foam is close to R-7 per inch and open cell around R-4 per inch. Also, closed cell becomes an air barrier at only 1” of application, while it takes on average 3” of open cell foam to achieve an air barrier. Another big difference in the two is that open cell is water permeable and closed cell is not. Open cell also has soundproofing qualities that can help in dampening outside noise.
|Qualities||Closed Cell Spray Foam||Open Cell Spray Foam|
|R-Value per inch:||R-7/inch||R-4/inch|
|Thickness needed to block air:||1”||3”|
|Used for sound dampening:||Sometimes||Yes|
|Most common location application:||Basements, crawlspaces||Attics, walls|
On new construction or major renovation projects, we can insulate exterior walls with spray foam or a combination of spray foam and traditional fiberglass batts through a process called “flash and batt.” For existing homes, spraying the attic and crawlspace/basement makes a substantial difference and leads to greater comfort and efficiency – without having to also insulate in walls. Insulating walls on existing homes is a bit invasive, so we can help clients avoid this by focusing on the top and bottom of the thermal boundary of the conditioned space.