What does open & closed cell mean exactly? There are two forms of spray foam:
Open and Closed cell.
Open cell has a less dense molecular structure and closed cell has a more dense molecular structure. Open cell spray foam is an air barrier and a vapor retarder. Commercial open cell is a spray on foam with thick thermal barrier that breathes enough to be safe but not enough to affect a thermostat.
Open cell is a type of foam where the tiny cells are not completely closed. Open cell is less expensive because it uses fewer chemicals. It is a very good air barrier but does not provide any type of water vapor barrier. It is much more sponge-like in appearance. It is often used for interior walls because it provides sound reduction. It is not recommended for outdoor applications.
Open cell is a type of foam in which the tiny cells that comprise it are not completely closed. It is typically less expensive because it uses fewer chemicals. While it is not recommended for outdoor applications, it can provide insulation in 2×6 walls and attics and sound reduction in interior walls during new home construction or renovations.
Open cell spray foam will not shrink or settle and offers:
R-Values (a measure of thermal resistance) up to R-19 in 2 x 6 construction
A rapid expansion rate of 150 times its size in seconds
Great sound barrier properties
An impermeable air barrier
An ideal solution for large voids, 2 x 6 or larger cavities, roof decks and cathedrals.
Closed cell spray foam is an air and vapor barrier. Open cell spray foam has a lower R-Value than closed cell spray foam. Commercial closed cell is a strong, hard high performance super insulation excellent against step, concrete or rigid foam not allowing any movement of air.
Closed cell foam insulation is much denser than open cell. It has a smaller, more compact cell structure. it is a very good air barrier as well as a water vapor barrier. It is often used in roofing projects or other outdoor applications, but can be used anywhere in the home as well.
Closed cell foam insulation is denser, because the cells contain less air and are more compact. Because it is structural in nature, it can be used anywhere in the home—including garages and basements—adding 300 to 400% more strength to the home and acting as a substantial barrier against mold- and mildew-causing moisture in finished basements.
Closed cell foam is ideal for masonry and 2 x 4 or 2 x 6 framing and metal buildings. It won’t shrink or settle and offers:
Higher R-Values, up to R-17 in 2 x 4 construction and R-28 in 2 x 6 construction
Increased racking strength (up to 330-400%)
An excellent vapor barrier at .1 Perm (minimum 2 inches).
Open cell spray foam can be cut into with a handsaw, or even a steak knife, while for closed cell you would need a power saw to cut into it.
Each type of insulation is used for specific applications, which is why a professional spray foam company should be called to share their expertise.