No Sheathing Under Roof

When open cell spray foam is used a low perm class ii vapor retarder is installed where required.

No sheathing under roof.

Underneath it is the attic space followed by a suspended ceiling. If you re wondering how to prevent condensation under a metal roof you re not alone. A leak free roof membrane that is fully adhered to the roof sheathing should be installed. 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.

Sheathing should be a minimum of 19 32 inch thick. 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. How to prevent condensation under a metal roof. Modern metal roofs are expected to last 30 years or longer.

Roof sheathing comes in grid marked 4 by 8 foot sheets and should be installed perpendicular to the frame. Never attach roof sheathing with staples. Here s how to fight back against the enemy within. Sheathing is installed perpendicular to roof trusses.

July 28 2017. 3 benefits of rigid foam sheathing. Plywood has an r value of 1 25 and fiberglass batts have an r value of 3 14. 8d ring shank nails should be used instead.

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.