How should insulation be installed over cementitious wood fiber deck panels?

When installing insulation over cementitious wood fiber deck panels, utilizing adhesive applied to a base sheet that is mechanically attached is the most effective and recommended method. This approach ensures that the insulation has a stable and secure attachment to the deck, helping to prevent any movement that could compromise the roof assembly's integrity.

Using mechanical fasteners directly into the deck, while a possible method in some situations, may not always provide the same level of uniformity and can introduce potential vulnerabilities where the fasteners penetrate the insulation or deck. Relying solely on weight for placement does not provide any secure or reliable attachment, which can lead to issues such as slippage or wind uplift. Additionally, installing foam under the deck panels may not be practical or effective since it does not align with standard roofing practices for achieving proper thermal performance and durability in roofing systems.

By applying an adhesive to a base sheet that is then mechanically attached, you create a method that not only enhances thermal resistance but also ensures a solid layer that can withstand the elements, contributing to the overall longevity and functionality of the roofing system.