Rafter And Purlin Spacing For Metal Roof

Visit the roof framing page for more information on cutting roof rafters and visit the roof pitch calculator for determining rafter lengths based on rise and run.

Rafter and purlin spacing for metal roof.

Correctly measure the spacing of furring strips for a metal roof to further decrease condensation. The spacing of purlins on roofs and girts on wall is usually 4 to 6 ft. Wider panels allow for greater spacing between rafters. Purlin spacing for metal roofing.

We do recommend it however. Without a set of blueprints with a pe s seal you have no option but to follow the inspectors gig. Load tables specifying safe loads for different spans are available from metal deck manufacturers. Standard gage are generally used for roofing.

The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to. Numbers 20 and 22 u s. Posted in metal roof roof types. Twenty four inches is a common spacing of furring strips for a metal roof.

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. Because this roof design doesn t have the added weight of plywood roof sheathing and metal roofs are generally lighter than asphalt shingle roofs the rafters have much less weight to bear than they would in a conventional design. Rafter span tables use these tables to determine lengths sizes and spacing of rafters based on a variety of factors such as species load grade spacing and pitch. Do all roofing projects require purlins.

The heavier the expected load is the shorter the distance between the purlins. Fyi we run purlins on 3 5 feet on center depending on size of purlin. However engineering determines the optimal spacing between the purlins. The most common measurement used for rafter spacing is either 16 or 24 inches.

A metal roof must also allow for some overlap on each side of the panels which will reduce the effective width of the panel. Spacing for purlins on a standard load most designs call for purlin placement at five foot intervals. You have to take the width of your roofing panel into the considerations. To know more about it read the following passage below that explain it into details.

Pole buildings with metal roofs are typically built with metal roofs resting directly on rafters and purlins horizontal members that run between rafters and tie them together. Purlin spacing is dependent on profile of the metal and gauge plus snow and wind load plus what the rafters are designed to carry. Purlins are usually supported by rafter building walls or the weight of the roof deck itself.