Osb Under Metal Roof

The first goal of roofing underlayment is to keep the roof deck dry before installation of the metal roofing material.

Osb under metal roof.

Traditionally metal roofs have used standard 30 pound felt paper underlayment. 1 some metal roofs will be more likely than others to telegraph any unevenness of the surface beneath them. Metal roofing roofing answers roofing installation roofing materials oriented strand board commonly referred to as osb is a type of engineered lumber similar to particle board formed by adding adhesives and then compressing layers of wood strands. 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.

Allen a couple of things to consider. April 3 2017 filed under. Cross purlin designs with 16 oc are sometimes called for. 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.

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. You can test fastener pull out resistance. Using nominal lumber 1x horizontal underneath and 2x vertical. 2 fastener pull out all depends on the condition of the 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. 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. Screws will do better than nails.