What is the Difference in Open and Closed Cell Spray Foam?
Spray foam is widely regarded as the best insulating material for buildings. Whether it is for commercial buildings accommodating offices or residential homes of family units, spray foam (also known as spray polyurethane foam, or SPF) is the superior material when compared to traditional ones like fiberglass and cellulose. It enhances energy efficiency by preventing thermal leakage through walls, reducing the cost of heating and cooling all year round. SPF is a two-component foam as two separate chemicals react to form the foam instantaneously as it fired from a nozzle. SPF comes in two forms – open cell and closed cell foam. We will compare and contrast the two so that you can decide which type you need for you particular situation.
Open Cell Foam
Open cell foam is a type of foam where the microscopic cells are not entirely sealed. While it does prove to be a good barrier to air, it is not good at blocking water molecules. It permeates water, making it inferior to its closed cell counterpart. Open cell foam is also called low density SPF or half pound foam since it weighs roughly 0.5 lbs. per cubic feet. This type of foam has an R-value (a thermal resistivity parameter) of 3.6 per inch, which is already higher than traditional building insulation materials. Open cell foam requires significantly less material to create, making it resource efficient and environment friendly. It is usually applied on interior walls as it provides good acoustic insulation but it is not applied outdoors since it is not water resistant. As a final note, open cell foam is much cheaper than closed cell foam so when money is an issue or if you only require air resistance or airtight seals, then open cell foam is your go-to choice.
Closed Cell Foam
Closed cell foam is a highly dense and tightly compressed foam in comparison to open cell foam. Due to its compact cell structure, it is impermeable to both air and moisture, making it water resistant. Closed cell foam is also called high density SPF or two pound foam because it weighs about 2 lbs. per cubic feet. This type of foam has a much higher R-value than open cell foam, at 6.5 per inch. This makes it a superior thermal insulator. This sort of foam has high tensile and bond strength, making it a good for reinforcing structural supports in walls. Hence, it performs two functions – provides topnotch thermal insulation and strengthens wall supports. As it is great for providing a good water barrier, it is frequently applied in outdoor applications, like on roofing materials. However, with all of these benefits comes the downside of cost; it is quite expensive. If you are willing to invest money in really good insulation, then closed cell foam is your best option.