No Sheathing Under Metal Roof

If you re wondering how to prevent condensation under a metal roof you re not alone.

No sheathing under metal roof.

How to prevent condensation under a metal roof. In order to add moisture barrier under metal roof you can spray the undersides of the roof by using a thick layer of polyurethane spray foam. Traditionally metal roofs have used standard 30 pound felt paper underlayment. Then the top of all your purlins once osb under metal roof panels is placed will be in the same plane and the roof steel will lay flat.

July 28 2017. If your home s existing shingles are pretty curled you could install a textured metal roof such as a metal shingle shake or tile directly over the curled shingles along with underlayment. For many applications a layer of plywood underneath your metal roofing is an unnecessary expense. Underlayment must also act as a secondary weather barrier in case the roof fails.

Here s how to fight back against the enemy within. My understanding is that with metal roofing you absolutely have to have a drainage plain. This would mean a plywood deck with some sort of building paper to handle the inevitable condensation that forms on the underside of the roofing. The best underlayment for metal roofs.

In order to avoid a hump at the transition from two layers of materials to one the notation on the building plans advises to lower the roof purlins in these areas by 7 16. Metal roofing panels rated for architectural use attached to purlins horizontal pieces of wood or metal fastened to roofing trusses are structurally sound when installed according to your roofing manufacturer s instructions and local building codes. Polyurethane spray foam metal roof insulation. It will help you to eliminate problems that may come when the house becomes extremely cold in the winter and terribly hot in the summer.

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