How Does Foam Insulation Affect Roof Shingles?

Structure

• Foam insulation has no significant effect on the structure of a roof or the way the shingles are attached. In many cases foam insulation is installed between rafters inside the attic after the installation of the roof and its top layer of shingles. Even when a roof incorporates foam panels for added insulation in the roof's structure, a waterproof membrane of roofing paper forms a smooth surface for attaching shingles.

Curling

• When shingles are exposed to excessive temperatures on one side, they can begin to curl. This occurs when the space inside an attic becomes too hot, with foam insulation preventing the air from escaping. Cool outside temperatures affect one side of the shingles, while hot attic temperatures affect the other side. This causes deformation and, in some cases, shingles that pull away and detach from the roof.

Longevity

• When foam insulation is installed properly, it keeps heat inside a home. This type of insulation is installed between ceiling joists and effectively sections off the space in the attic from the home's living area. Since hot air from a furnace never reaches the attic, it can't heat shingles unevenly. This extends the lifespan of wood or asphalt shingles while reducing home heating costs.

Vented Roofs

• A vented roof, which uses active airflow to cool the space below shingles, relies on hollow roof baffles to provide a space between foam insulation in the attic and the roof. Ventilation in an attic can also take the form of an attic fan that exhausts hot air. Ventilation can minimize the impact of foam insulation on shingles.