Spray Foam: Open-Cell vs. Closed-Cell
Spray foam insulation is well-known for its ability to provide superior thermal control in both residential and commercial settings. It can be used as a continuous exterior insulation solution, as well as in wall cavities and attics. Understanding the distinctions between open and closed cell spray foam insulation is important for proper sealing and insulating of your home's walls and attic.
The physical architectures of open-cell and closed-cell spray foam differ, giving them variable thermal and acoustic performance attributes. Understanding how foam insulations are made is critical when considering these discrepancies. Foam insulation is created by combining two substances that expand fast when they come into contact.
The difference between the little bubbles (cells) that make up spray insulation is referred to as open cells versus closed cells.
The open-cell foam contains cells that have not been fully encapsulated. To put it another way, the cells are purposefully left exposed. As a result, the foam becomes softer and more pliable.
Closed-cell foam is formed composed of cells that are totally closed, as the name implies. Because the cells are pushed together, air and moisture cannot enter the foam. Closed-cell foam is substantially more robust and stable than open-cell foam as a result of this.
The bubbles in open-cell spray foam break, leaving just the struts (the point where two bubbles touched each other), as illustrated in the illustration on the left. The bubbles in closed-cell insulation do not burst, resulting in interconnected closed pockets.
The R-value of closed-cell spray foam is R-7 per inch. Open-cell spray foam, on the other hand, has an R-value of R-3.8 per inch. Furthermore, the density of the materials differs significantly. Closed-cell spray foam has a density of 2lbs/ft3, whereas open-cell spray foam has a density of 0.5lb/ft3.
While both materials can be used as an air barrier, only closed-cell spray foam can generate a completely sealed system that can be utilized as an air and vapour barrier. Open-cell spray foam, on the other hand, has a porous structure that allows for better acoustics than closed-cell spray foam.
While open-cell spray foam is less expensive in terms of material costs than closed-cell spray foam, the disparity in R-values means that any system utilizing open-cell spray foam will require more material than a system using closed-cell spray foam to attain a given R-value.
While both open and closed-cell spray foam will completely fill the cavities where they are installed (if done correctly), only closed-cell spray foam can provide a vapour barrier. Closed-cell spray foam insulation will offer the required vapour barrier and insulation in one package if the application requires it. As a result, all continuous external spray foam insulation treatments should be closed-cell.
The Advantages of Closed Cell Foam
Closed-cell foam, which can reach 2x the R-Value of open-cell inside a conventional wall, is the greatest choice for robust insulating where space is limited. Its rigidity contributes to the building's structural integrity, and E84 fire-rated variants are available. The closed cell also works as a vapour barrier, making it less likely for water and moisture to enter the home, and the foam itself is unaffected by water damage.
The Advantages of Open Cell Foam
One of the most significant advantages of open-cell foam is that it expands significantly after application, allowing it to insulate hard-to-reach nooks and crannies in a home. Closed-cell foam can be difficult to insulate in certain situations. Open-cell foam is ideal for soundproofing since it can completely cover the space between studs with just one application.
Although open-cell foam is less expensive than closed-cell foam, it does not insulate a home as well as closed-cell foam, making it unsuitable for areas with extreme weather conditions.
JM Editors. (Jun. 10, 2022). Spray Foam: Open-Cell vs. Closed-Cell. Johns Manville. Retrieved from: https://www.jm.com/en/blog/2020/june/spray-foam--open-cell-vs--closed-cell/#:~:text=Closed%20cell%20spray%20foam%20has,foam%20is%202lbs%2Fft3.
Open Cell vs Closed Cell Foam: Which Should I Choose? Tiger Foam Insulation. Retrieved from: https://tigerfoam.com/sprayfoaminsulation/open-cell-vs-closed-cell-foam-which-should-i-choose/