Purlin Spacing For Corrugated Metal Roofing

Kiln dried softwood is recommended for purlins or decking pine fir hemlock and spruce.

Purlin spacing for corrugated metal roofing.

We do recommend it however. Minimum recommended purlin size is 4 x 2 50mm x 100mm in timber or z140mm x 1 6mm in steel. Z purlins are connected to the rafters using cleats. You can use both types of corrugated roofing together creating panels that will allow light to come through as with a clear or white fiberglass corrugated panel known as a skylight.

When using purlins fabral recommends a maximum spacing of 24 on center note that 5v requires solid decking. Be sure the larger edge is laid so that the small edge of the next panel will overlap it. All purlin joints must be supported by a rafter. The overlaps ends and sides depends upon the sloop of the roof see below.

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. For the lighter material such as lightweight aluminum the common spacing length is 4 inches of clear gap. However sometimes corrugated sheets are 39 wide instead of 37 wide.

Purlin spacing should suit the end laps required for the size of sheet to be used. Purlin spacing for metal roofing. Purlins provide horizontal support for the sheets and form part of the framework for the building. The typical spacing standards for residential and commercial buildings are about 1 to 2 foot.

The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to. Purlin spacing is dependent on profile of the metal and gauge plus snow and wind load plus what the rafters are designed to carry. There will be four screws per screw line placed in the high of the corrugated panel. Corrugated metal panels often called tin because in the past such panels were sometimes made of tin are typically steel or aluminum sheets that are used as a roofing material.

Corrugations should run in a straight line between the highest and lowest points and at a right angle to the purlins the intermediate supports. Pullout values decrease if the fasteners protrude completely through the purlins. The diagram above is a typical 37 wide panel and the spacing works out perfectly. When framing the roof the spacing for roof trusses should not exceed 24 inches 61 cm and purlins should not exceed 36 inches 91 cm apart.

Do all roofing projects require purlins. Fyi we run purlins on 3 5 feet on center depending on size of purlin. Corrugated sheet roofing material is widely available and easy to use. These panels can cost more to install that a traditional roof but in the long run are often a better value.

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