The roof decking may be the layer of plywood or O.S.B. nailed towards the trusses or rafters. Roof decking is usually seven/sixteen” and is available in 4’x8’ sheets. When you’re tearing off aged roofing, the roofer can search for damage that should be fixed after the deck is bare. Also, https://portaltrendz.com/4-roofing-contractors-recommended-in-oswego-il-top-local-experts-for-your-roofing-needs/