The difference between open and closed cell Spray foam.
| Perfomance | Open Cell | Closed Cell |
| R-Value per inch | R3 – R4 | R7 |
| Moisture Barrier | POOR very porous, allows water vapor and liquid water to penerate |
EXCELLENT non-porous, not moisture-penetrable |
| Air Barrier | GOOD | EXCELLENT |
| Mold Resistance | Does not Mold | Does not Mold |
| Increase Structural Integrity | NO | Yes |
| Sound Barrier | Excellent | Poor |
| Uses | Interior walls, conditioned attic, floors(not basement), sound deadening. Should not be used for exterior or in applications where it will be in direct contact with water | Basement Walls, Crawl Spaces, Between Radiant-Heated Floors. Exterior Bathroom Walls, Foundation Exteriors |
There are two types of spray foam – open and closed cell. Open cell is often referred to as ½ pound foam (0.5 lb/cu ft) while closed cell is typically called 2 pound foam (2.0 lb/cu ft). Open cell foam cells are not completely closefd and air fills all of the “open” space inside the material. In closed cell foam, all of the tiny foam cells are closed and packed together giving it a higher density and greater insulating properties.
There is a big difference between open and closed cell in terms of cost, application and performance. While closed typically costs twice as much as open cell, it has a higher R-value per inch and it’s more effective air and moisture barriers. Because of closed cell performance it’s a better choice for basements, crawl spaces, bathrooms and other areas where moisture is a problem. Open cell foam is an excellent choice as a thermal insulator and air barrier for internal wall cavities and conditioned attics given its lower price.
