Metal Roof Installed Over Purlins

As long as the plywood under the shingle roof is in good condition this way can provide many benefits.

Metal roof installed over purlins.

Work at a comfortable steady pace trying not to rip up or carry off too much old roofing at once. Use 1 1 4 inch nails to cover the outline of the roof with strips of metal eave flashing also called edging. The second way to install a metal roof over a shingle roof is with the use of purlins or battens. Purlins are 2 by 4 feet and are installed much like metal roofing.

We do recommend it however. 3 install 1x4 purlins down over the shingles before installing the metal roof the third way to install a metal roof over shingles is by applying 1x4 purlins over the shingle roof. They give added support to the roof and also provide a nailing surface for the end panels and drip edge. Do all roofing projects require purlins.

They are installed on top of the roof rafters with a felt underlayment or vapor barrier installed on top. The spacing of your purlins depends on the expected snow and wind load. This is by far the most common way to install a metal roof. Although you can install corrugated metal roofing over shingles for the best foundation it is recommended that all the old roofing be removed.

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 purlins are screwed or nailed down to the roof deck depending on how the metal roofing manufacture has testing for their roofing panels and then the metal is installed to the purlins. Place corner pieces where panels will meet bends at the edge of the roofing. The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to.

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.