Do You Need Plywood Under Metal Siding

Do you need plywood under metal roofing.

Do you need plywood under metal siding.

Plywood cabinets the wood that goes under residential siding exterior sheathing performs several functions. Rotted sagging areas in your roof s plywood decking should be replaced prior to installing metal panels in order to prevent costly repairs in the future. 1 you said some metal roofing should never have firring strips i have certainly seen that with some of the very thin steel or weak aluminum decking which could never stand even a foot of free span over firring strips without crumpling buckling under someone walking on it so they would have to lie flat on the water barrier over the sheathing. It adds insulation waterproofing and structural support for the framing.

It depends if you need the shed heated for any thing if not no you do not need a plywood layer. For many applications a layer of plywood underneath your metal roofing is an unnecessary expense. Ensure that the plywood deck is strong enough to withstand the added weight of the metal panels. No the purposes of the plywood roof decking are to give lateral stability to the rafters trusses and create a walking surface.

In a barn shop or other outbuilding you can attach your metal roof directly to the purlins.