Spray insulation expands when introduced to oxygen. When the insulation is applied it begins to expand to fill in cracks and crevices.
This process can produce insulation 5 to 10 times its size when wet. Also, since the insulation can be sprayed into small areas, the ability to insulate hard-to-reach places is greatly increased.
This allows for greater coverage of insulation in new construction and existing buildings.
When the insulation has dried, it creates an airtight seal. Compared to fiberglass insulation, where air can permeate the surface, spray foam insulation becomes a hard, impermeable surface.
By creating an airtight seal, the air inside of a building has a harder time escaping, which results in lower energy use.
The surface of hardened spray foam also eliminates the accumulation of vapor. By having an impermeable surface to air, convection is unable to occur.
Convection is the transfer of warm air to an area of cold air. When warm air is introduced to cold air, the moisture in the warm air is released and causes condensation.
Since air cannot travel through the spray foam, convection is ceased, and vapor collection is avoided.