The answer to 'what is roof decking' is the structural base of a roof, which is typically made of wood panels or boards that provide a solid foundation for the roofing materials. Roof decking is installed directly on top of the roof's supporting trusses or rafters, and it serves as the base layer that the roofing shingles, tiles, or other materials are attached to.
Roof decking is an essential component of a roof system, as it helps distribute the weight of the roofing materials and any additional loads, such as snow or wind, across the entire structure. It also provides a surface for the installation of underlayment, which is a protective layer that helps prevent water leaks and other moisture-related issues.