Metal Roof Installed Over Purlins

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

Metal roof installed over purlins.

As long as the plywood under the shingle roof is in good condition this way can provide many benefits. Although you can install corrugated metal roofing over shingles for the best foundation it is recommended that all the old roofing be removed. 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 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.

Work at a comfortable steady pace trying not to rip up or carry off too much old roofing at once. They are installed on top of the roof rafters with a felt underlayment or vapor barrier installed on top. Purlins are 2 by 4 feet and are installed much like metal roofing. Metal roof purlins are installed horizontally under metal roofs.

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. The second way to install a metal roof over a shingle roof is with the use of purlins or battens. 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. Use 1 1 4 inch nails to cover the outline of the roof with strips of metal eave flashing also called edging.

They give added support to the roof and also provide a nailing surface for the end panels and drip edge. We do recommend it however. The topic we want to discuss today is the purlin installation. This is by far the most common way to install a metal roof.

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.