Installing Metal Roof On Purlins

Snap a chalk line horizontally across the roof two feet down from the top.

Installing metal roof on 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. The purlin are ultimately used to fasten the roof steel providing a diaphragm effect along with the siding when properly engineered and installed. The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to. As long as the plywood under the shingle roof is in good condition this way can provide many benefits.

When using plywood nail it directly to the purlins and screw the metal roofing panels through the plywood into the purlins as instructed by the manufacturer. Lay the first purlin at the ridge of. Install the roofing screws vertically along each rib in the panel. In this installation the vapor barrier is installed on the side of the insulation nearest the interior of the building.

Align the first metal roofing panel so that it overlaps the edging by 1 2 to 3 4 of an inch and is square to the roof line. Spacing is typically 24 on center in low snow loads and is reduced based upon truss span and snow load. Set the second. Purlins are dimensional lumber that are fastened to the top chord of trusses connecting them together for bracing purposes.

How to install metal roof purlins step 1. 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. Installation of pole barn purlins. One of the first things to ensure a successful metal roof installation is to measure the roof length and slope correctly and precisely.

Run a tape measure from end to end along the rafters of the roof to determine how many purlins will be needed.