Metal Roof Over Purlins

Metal roof purlins are installed horizontally under metal roofs.

Metal roof over purlins.

If your home s existing shingles are pretty curled you could install a textured metal roof such as a metal shingle shake or tile directly over the curled shingles along with underlayment. They are installed on top of the roof rafters with a felt underlayment or vapor barrier installed on top. 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. The spacing of your purlins depends on the expected snow and wind load.

Do all roofing projects require purlins. If there are gutters installed on the eaves the eave flashing should be installed to overhang the lip of the gutter by about 1 2 inch. Use 1 1 4 inch nails to cover the outline of the roof with strips of metal eave flashing also called edging. 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.

They give added support to the roof and also provide a nailing surface for the end panels and drip edge. You also could install a corrugated through fastened metal roofing product and probably not have issues. The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to. Purlins are 2 by 4 feet and are installed much like metal roofing.