The roof decking would be the layer of plywood or O.S.B. nailed to your trusses or rafters. Roof decking is typically 7/16” and is available in four’x8’ sheets. In the event you’re tearing off previous roofing, the roofer can hunt for destruction that needs to be repaired after the deck https://house-challenge.com/5-ways-to-get-affordable-roofing-services-in-aurora-illinois-insider-tips-and-tricks/