Metal Roof Over Purlins

The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to.

Metal roof over purlins.

And the purlins need to be fastened securely into the rafters trusses too and for some wind loadings the decking sheathing needs to be screwed down to the. 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. Purlins are non pressure treated 1 x 4 x 12 lumber that is installed on to the roof in a specific layout pattern and screw pattern. Metal roof purlins are installed horizontally under metal roofs.

Use 1 1 4 inch nails to cover the outline of the roof with strips of metal eave flashing also called edging. They are installed on top of the roof rafters with a felt underlayment or vapor barrier installed on top. You also could install a corrugated through fastened metal roofing product and probably not have issues. Do all roofing projects require purlins.

Place corner pieces where panels will meet bends at the edge of the roofing. The spacing of your purlins depends on the expected snow and wind load. Purlins are 2 by 4 feet and are installed much like metal roofing. Pay attention also to the fastening of the purlins to the roof structure if they are not fastened down well enough to carry the design uplift load the roof can come off purlins and all.