Spray Foam Insulation - Subfloor Insulation

The addition is raised, and the foundation is open, leaving the subfloor and the room above it subject to the elements. Installing fiberglass insulation in these conditions would result in the material being damaged quickly and would act as an air filter because the material is ineffective if it is not enclosed on all sides. The homeowners chose to have closed cell spray foam applied to the subfloor at a 2-inch thickness. This provides an air barrier and a vapor retarder, preventing cold floors in the winter, and protecting the floors from the elements.