Osb Under Metal Roof

The best underlayment for metal roofs.

Osb under metal roof.

The first goal of roofing underlayment is to keep the roof deck dry before installation of the metal roofing material. Underlayment must also act as a secondary weather barrier in case the roof fails. Using nominal lumber 1x horizontal underneath and 2x vertical. Cross purlin designs with 16 oc are sometimes called for.

The only reason to put osb on a roof would be in the case of a very narrow very long very tall building with high wind loads ones which would exceed the wind shear carrying capacity of the steel. You can test fastener pull out resistance. 1 metal 2 air space of 3 4 or greater using 1x4 or 2x4 purlins 3 wrb and 4 5 8 to 3 4 of ply or osb. Osb is widely used as roof decking material.

Metal should be installed using a cold roof design so the typical metal assembly would be. Screws will do better than nails. Traditionally metal roofs have used standard 30 pound felt paper underlayment. This case is most certainly the exception to the general rule and happens in far less than 5 of all post frame buildings.

1 some metal roofs will be more likely than others to telegraph any unevenness of the surface beneath them. 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. 2 fastener pull out all depends on the condition of the osb. April 3 2017 filed under.