Metal Roof Over Purlins

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.

Metal roof over purlins.

Do all roofing projects require purlins. Use 1 1 4 inch nails to cover the outline of the roof with strips of metal eave flashing also called edging. You also could install a corrugated through fastened metal roofing product and probably not have issues. 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.

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. 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. 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. Metal roof purlins are installed horizontally under metal roofs.

The spacing of your purlins depends on the expected snow and wind load. They are installed on top of the roof rafters with a felt underlayment or vapor barrier installed on top. 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. Purlins are 2 by 4 feet and are installed much like metal roofing.