Osb Under Metal Roof

This case is most certainly the exception to the general rule and happens in far less than 5 of all post frame buildings.

Osb under metal roof.

Underlayment must also act as a secondary weather barrier in case the roof fails. 2 fastener pull out all depends on the condition of the osb. 1 some metal roofs will be more likely than others to telegraph any unevenness of the surface beneath them. 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 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. Using nominal lumber 1x horizontal underneath and 2x vertical. 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. Traditionally metal roofs have used standard 30 pound felt paper underlayment.

The best underlayment for metal roofs. Metal should be installed using a cold roof design so the typical metal assembly would be. Allen a couple of things to consider. The first goal of roofing underlayment is to keep the roof deck dry before installation of the metal roofing material.

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. Osb is widely used as roof decking material. Cross purlin designs with 16 oc are sometimes called for. You can test fastener pull out resistance.