What type of foam insulation is commonly used in roofs?

Closed-cell spray foam is commonly used in roofs due to its excellent insulation properties and ability to provide an air barrier. This type of foam has a higher R-value per inch compared to other insulation materials, making it very effective for resisting heat transfer. Its structure, which consists of numerous small, closed cells filled with gas, contributes to its ability to create a solid, continuous layer of insulation that minimizes air leakage.

Additionally, closed-cell spray foam is also moisture-resistant, which is particularly beneficial in roofing applications where water exposure can lead to mold growth and other structural issues. Its adhesive properties allow it to bond well to various substrates, providing excellent coverage and reducing the risk of gaps where heat can escape.

In contrast, other insulation options like open-cell spray foam and fiberglass batts may not provide the same level of moisture resistance or air sealing capability, making them less suitable for roofing applications where these characteristics are critical. Rigid board insulation offers good thermal performance but does not conform as easily to irregular roof shapes and may require additional measures for air sealing and moisture protection.