Installing Metal Roof On Purlins

Install the roofing screws vertically along each rib in the panel.

Installing metal roof on purlins.

Run a tape measure from end to end along the rafters of the roof to determine how many purlins will be needed. Purlins are dimensional lumber that are fastened to the top chord of trusses connecting them together for bracing purposes. 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. Snap a chalk line horizontally across the roof two feet down from the top.

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. Lay the first purlin at the ridge of. 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.

In this installation the vapor barrier is installed on the side of the insulation nearest the interior of the building. Spacing is typically 24 on center in low snow loads and is reduced based upon truss span and snow load. This is by far the most common way to install a metal roof. Be sure the larger edge is laid so that the small edge of the next panel will overlap it.

The purlin are ultimately used to fasten the roof steel providing a diaphragm effect along with the siding when properly engineered and installed. How to install metal roof purlins step 1. 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. Installation of pole barn purlins.

Each panel should be cut to the exact size or there could be imprecise cuts and rough edges exposed to the elements leading to rust and roof coating failure.