How do I Choose the Best Spray Foam Insulation?

Spray foam insulation is used in home improvement to increase the energy efficiency of the house, lowering the heating and cooling costs. When choosing the best insulation for your home, consider the climate in which you live, the size of your home, and how much money you can afford to spend.

This type of insulation is released as a liquid that is composed of a polymer, usually polyurethane or modified urethane, and a foaming agent. The process of applying this insulation material is relatively simple. A nozzle is inserted behind the wall, under the floor or in the ceiling, via a small hole. The liquid is sprayed through the nozzle where it turns into foam and fills the area completely. There are three main types of spray foam insulation: 3-pound foam (1.36 kg), 2-pound foam (0.9 kg) and 0.5-pound (0.23 kg) foam.

Three-pound (1.36 kg) spray foam is mostly used in roof and attic insulation. It is the most expensive of this type of insulation because it is also the most dense. The foam has an R-value (resistance to heat flow) of 6, meaning it can trap gases denser than air. Depending on the climate in which you live, this could be an advantage or a disadvantage. People who live in hot, dry climates would benefit most from three-pound (1.36 kg) foam, as it keeps the temperature in the attic within 10°F (12.22°C) of the temperature in the house. Houses located in wet climates should avoid this type of spray foam, as it may trap moisture between the roof and the insulation, causing the roof to rot over time.

Two-pound (0.9 kg) spray foam, also known as closed cell spray foam, has an R-value between 4 and 5, making it perfect for insulating walls and tanks. It keeps the heat inside during the winter and outside on hot summer days. This spray foam is most often used in small buildings where air and vapor control is necessary. The cost per R-value is higher than it is with half-pound (0.23 kg), because of the greater resistance to the leakage of air or gases.

Half-pound (0.23 kg) spray foam is the most cost-effective, and therefore most popular, spray foam insulation. It has an R-value between 2 and 3.5, making it about as dense as dormant air. It is used as the primary insulation material in the wall cavities of most home. Because of its low R-value, it is not approved for vapor and fume control, but still has the same insulation characteristics of the 2-pound (0.9 kg) foam.