2 Layers Of Roof Sheathing

Skinning over old sheathing does occur but i have never seen someone skin over plywood in that condition.

2 layers of roof sheathing. More expensive because of the additional labor and materials peeling off the old roof down to the sheathing is your only option if you already have two layers. This old house general contractor tom silva prefers this route even when the roof is just a single layer so he can find the source of any water damage upgrade the flashing and install. Should you sandwich roof sheathing between two impermeable layers. And if you re still wondering what roof sheathing is and what materials are typically used read on and satisfy your curiosity.

The exposed edges of the 3 layers of rigid insulation are no longer exposed. Based on the pictures alone i don t know what to say. A lower layer conventionally nailed to the rafters and an upper layer installed as a nailing surface for the roofing material on top of the rigid foam. I think there are better ways to design an unvented roof for example by using rigid foam above the roof sheathing instead of closed cell spray foam on the underside of the roof sheathing.

Plywood used for roof decking is typically called sheathing and carries a grade stamp indicating its load and span ratings and other performance factors. Comes in standard 4 by 8 foot sheets is strong. Can you double up plywood roof sheathing without inviting disaster 2000 sf of 1 2 cdx ply went on the roof before i had a chance to take a look at it and it is really sorry stuff. In my view two layers of felt atop roof sheathing would not significantly improve the leak resistance of an asphalt shingle low sloped roof.

I italicized atop because on very low slope roofs some shingle installation applications specify interlaying a course of felt underlayment perhaps using 30 felt between every shingle course as part of. It s up to you. The type of fasteners used and the way they need to be spaced for the top layer of sheathing depend on the pitch of the roof. It got nailed over 2 x 12 joists 24 o c.

Roof sheathing materials plywood. I m not a fan of spray foam. On a 2 12 pitch roof. Poor ventilation from a past roof along with 3 ply equals that delamination.

I am replacing a roof right now built in 1982 and the 3 ply is delaminated pretty heavily. The illustration shows two layers of osb or plywood roof sheathing.