Metal Roof Installed Over Purlins

The spacing of your purlins depends on the expected snow and wind load.

Metal roof installed over 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. Metal roof purlins are installed horizontally under metal roofs. The second way to install a metal roof over a shingle roof is with the use of purlins or battens. 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.

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. Place corner pieces where panels will meet bends at the edge of the roofing. 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. Although you can install corrugated metal roofing over shingles for the best foundation it is recommended that all the old roofing be removed.

As long as the plywood under the shingle roof is in good condition this way can provide many benefits. The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to. They are installed on top of the roof rafters with a felt underlayment or vapor barrier installed on top. We do recommend it however.

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. This is by far the most common way to install a metal roof. Purlins are 2 by 4 feet and are installed much like metal roofing.

Work at a comfortable steady pace trying not to rip up or carry off too much old roofing at once.