What additional layer is typically used for mechanically fastening perlite on wood decks?

The use of fiberglass felts as an additional layer for mechanically fastening perlite on wood decks is significant due to their properties that enhance the roofing system's overall stability and performance. Fiberglass felts are designed to provide a strong, waterproof barrier that aids in securely bonding perlite, which is a lightweight insulating material often used in roofing applications. The felts help to create a surface that is conducive to the mechanical fastening of perlite, ensuring that the insulation remains in place and performs effectively over time.

In addition, fiberglass felts are resistant to moisture and provide good tensile strength, which is essential when dealing with the stresses and potential movement in roofing materials. Their compatibility with roofing systems makes them an ideal choice for ensuring that the underlying structure remains protected while also contributing to the overall insulation and energy efficiency of the roof.