The roof decking is the layer of plywood or O.S.B. nailed into the trusses or rafters. Roof decking is often seven/16” and is available in four’x8’ sheets. In the event you’re tearing off old roofing, the roofer can look for destruction that should be repaired once the deck is bare. https://portaltrendz.com/4-roofing-contractors-recommended-in-oswego-il-top-local-experts-for-your-roofing-needs/