Polyurethane Foam, Overall Length : 45mm

While not the most abundant of insulations, polyurethane foams are an excellent form of insulation. Nowadays, polyurethane foams use non-chlorofluorocarbon (CFC) gas for use as a blowing agent. This helps to decrease the amount of damage to the ozone layer. They are relatively light, weighing approximately two pounds per cubic foot. They have an R-value of approximately R-6.3 per inch of thickness. There are also low density foams that can be sprayed into areas that have no insulation. These types of polyurethane insulation tend to have approximately R-3.6 rating per inch of thickness. Another advantage of this type of insulation is that it is fire resistant.