The roof deck
is the roofing material layer between the primary structural components (trusses & joists) and either insulative layers or weatherproofing layers in a typical roof system. Usually the roof deck acts as a unifying structural diaphragm by tying all the structural components together. There are many types of roof deck: plywood
sheathing, wood tongue and groove, corrugated metal, grancrete
, reinforced concrete, and double tee.