Osb Under Metal Roof

Allen a couple of things to consider.

Osb under metal roof.

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. 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. 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. 2 fastener pull out all depends on the condition of the osb. 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. Underlayment must also act as a secondary weather barrier in case the roof fails.

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. The first goal of roofing underlayment is to keep the roof deck dry before installation of the metal roofing material. Screws will do better than nails. 1 some metal roofs will be more likely than others to telegraph any unevenness of the surface beneath them.

Metal should be installed using a cold roof design so the typical metal assembly would be. Osb is widely used as roof decking material. April 3 2017 filed under. Using nominal lumber 1x horizontal underneath and 2x vertical.