Installing Metal Roof On Purlins

Installation of pole barn purlins.

Installing metal roof on purlins.

One of the first things to ensure a successful metal roof installation is to measure the roof length and slope correctly and precisely. 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. Lay the first purlin at the ridge of. Snap a chalk line horizontally across the roof two feet down from the top.

Purlins are dimensional lumber that are fastened to the top chord of trusses connecting them together for bracing purposes. 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. 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. In this installation the vapor barrier is installed on the side of the insulation nearest the interior of the building.

This is by far the most common way to install a metal roof. How to install metal roof purlins step 1. The purlin are ultimately used to fasten the roof steel providing a diaphragm effect along with the siding when properly engineered and installed. Set the second.

Install the roofing screws vertically along each rib in the panel. The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to. Run a tape measure from end to end along the rafters of the roof to determine how many purlins will be needed. 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.

Spacing is typically 24 on center in low snow loads and is reduced based upon truss span and snow load.