No Sheathing Under Roof

The current state and local building codes for the minimum r value of air impermeable insulation required for the roof assemblies in the home s climate.

No sheathing under roof.

When open cell spray foam is used a low perm class ii vapor retarder is installed where required. How to prevent condensation under a metal roof. Modern metal roofs are expected to last 30 years or longer. Currently there is no sheathing or tar paper under the metal.

8d ring shank nails should be used instead. Sheathing is installed perpendicular to roof trusses. Never attach roof sheathing with staples. July 28 2017.

Here s how to fight back against the enemy within. Plywood has an r value of 1 25 and fiberglass batts have an r value of 3 14. It is nailed directly to the rafters. More effective insulation with r values ranging from 3 6 to 8 0 rigid foam sheathing has much better insulation per inch than other materials i e.

Sheathing should be a minimum of 19 32 inch thick. While metal roofing doesn t require plywood underlayment there are circumstances in which you may wish to install plywood to anticipate future roofing needs or to offer additional soundproofing. A leak free roof membrane that is fully adhered to the roof sheathing should be installed. If you re wondering how to prevent condensation under a metal roof you re not alone.

Owners of agricultural buildings man caves and horse barns all are worried about the corrosive effects of condensation.