Spray Foam Insulation is a two-component system typically consisting of petroleum oils, plastics, and resins. The polyurethane foam comes in two different forms, open cell and closed cell foam. The polyurethane spray foam is an extremely versatile material that is available in a variety of final physical properties and densities. Although the two types of foam are very similar in their chemical structures their characteristics and capabilities differ in many ways, which makes it necessary for the user to understand the differences of the two materials so he or she can determine which is the right foam for their particular application.
The open cell spray foam insulation contains a density of 0.5lb. per cubic foot. The greater the density of the foam the heavier, or stronger it will become. This particular type of polyurethane foam is referred to as "Open Cell" because of the nature of the chemical reaction during the installation process. When the polyurethane foam is being applied the tiny cells of the foam are broken causing air to fill the "open" space inside the material, resulting in a soft or spongy material. The open cell foam carries an R-Value of 5 to 5.5 per inch (R-Value is the measure of thermal resistance, which can be found by identifying the ratio of the temperature difference across an insulator and the heat flux). 0.5lb. foam products use significantly less material than 2lb. foam products do when completing the same sized job, making them attractive to an individual concerned with conserving the foam material. Due to the fact that open cell foam requires less material, the cost of the project is much cheaper than it would be if you were to apply closed cell foam. Although, Open cell foam is an efficient and economical product it contains some disadvantages in regards to closed cell foam. One of the open cells disadvantages is it has a lower R-Valuer per square inch than closed cell foam does and open cell foam is vapor permeable requiring it to be covered with a vapor retardant material. Although, open cell foam has some advantages and disadvantages it has been recognized as an excellent insulator, air sealant and sound barrier.