What Makes Spray Foam Insulation?

Spray Foam Insulation (SPF) is made by combining an isocyanate ( A side ) and a resin (b side) at a 1:1 ratio. Isocyanates in polyurethane is typically made up of methylene diphenyl disoycynate (MDI) and polymeric methylene diphenyl disocynate (PMDI). Resins in polyurethane are usually made up of polyols and catalysts.   Different foams may use catalysts within the foam to help the reaction occur. A common catalyst in spray foam insulation is a blowing agent. A blowing agent is a substance in the foam that produces a cellular structure that effects the way the foam hardens. The common blowing agents used in most foams are water and hydrocarbons based on the foam type. Open cell spray foam insulation usually has a water blown agent and closed cell typically has water and a hydrocarbon which forms the foam.

The two components A and B, are then disposed through a proportioning system that evenly distributes the chemicals that are then ran through a hose and mixed through the spray gun. When spraying, the chemical reaction is created to make spray foam insulation that comes out as a liquid and adheres to a surface and expands and sets. Open cell insulation tends to have a spongy like texture, as closed cell insulation is a ridged more tough texture due to its water impermeable properties.

The types of foam created vary from Low, Medium and High Density. High Density foams are referred to as closed cell foams used for roofing or concrete lifting applications. Medium Density foams are also categorized as closed cell foams typically used in structures for insulating purposes. Low Density foams are referred to as open cell foams that are used in structures  for insulating purposes.  It is important to follow all foam manufacturers guidelines in regards to handling these products and should always have proper personal protection equipment on when handling these products. It is recommended that a trained and certified applicator handle and process these materials.