Roofing question: Do I NEED 5/8″ plywood decking under a 50-year steel roof?
House 6:12 pitch, garage 3.5:12 pitch
Trusses 24″ OC, 2X6 top cord (solar ready). Climate zone 6A, mid to low snow load.
I’ve already moved off the 7/16″ OSB decking that is on the plans, and have temporarily settled on 1/2″ plywood decking for the roof. Roofing contractor said this would be much better for the screw holding power (using click-lock standing seam panels, 26 gauge, 16″ wide). Now the question is would I see any benefit over time going to a 5/8″ plywood roof decking? The cost is incremental vs 1/2″ ply (let’s call it 1k), but it all adds up, and if 1/2″ is plenty i am content leaving it at that. Will 1/2″ ply sag over time on 24″ OC trusses, and if so will 5/8″ provide any benefit for this over a 50 year life span? Assume venting will be more than adequate (full length ridge vent gable roof, full vented soffits).