how spray foam works

Polyurethane spray foam is a type of insulation that is applied into the home to insulate walls, ceilings, under floors and the underside of roof decks. It is more effective than traditional insulation because it expands to fill difficult to reach places and anywhere else you would use insulation for thermal resistance or sound proofing. Highly efficient insulation of the building envelope is the baseline for all energy efficiency strategies that, in turn, allow for reduction in the cost of auxiliary whole house systems like the HVAC system or even a grid-tied solar system.

Polyurethane spray in place foam insulation is a two component process of combining an isocynate and a resin with the resin being the "secret sauce" that distinguishes one manufacturer's product from another. The A and the B component are combined at exacting proportions under heat and pressure to expand within seconds to a volume 120 times the volume of the original liquid components. Modern spray foam insulations have no off gassing properties such as the spray foam insulations of the 1970s did and will adhere to almost any clean, dry surface. Because it can be applied monolithically, that is, without seams, it a much more effective air-barrier than batt or sheet types of insulation, the seams of which must be painstakingly sealed by hand to achieve the same results that foam does in a single pass.

Polystyrene and fiberglass insulation cover small holes, but they do not seal them. Spray foam insulation expands to fill up cracks and crevices, and it can be applied to places other types of insulation can’t reach such as the underside of a roof deck, the rim joist area of a two story home or the underside of a pier and beam floor. Spray foam prevents not only the entry of hot and cold air, but also effectively reduces the entry of airborne dust and pollen into the home. Also, the entry of many insects and pests into the home is deterred by a building envelope comprised of spray foam insulation. Spray foam insulation is used in new houses as they are being built, but it can also be used in existing buildings to insulate places the old fiberglass insulation cannot reach, or in crevices that have developed as the structure settled.

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