Rafter And Purlin Spacing For Metal Roof

A metal roof must also allow for some overlap on each side of the panels which will reduce the effective width of the panel.

Rafter and purlin spacing for metal roof.

The wider the roofing panels the greater spacing distance you should put. The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to. Contact fabral for additional information. This will provide a solid framework for attaching the metal panels.

I did not know. Without a set of blueprints with a pe s seal you have no option but to follow the inspectors gig. The inspector asked about the type of wood being used as purlins. We do recommend it however.

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. Do all roofing projects require purlins. The cos of the purlin spacing is because the load on the purlins is vertical and the purlin spacing is with the run of the roof. There is a chance of damaging roofing sheets if you are failed to do so.

For sake of discussion we will assume a minimal roof snow load of 20 psf pounds per square foot and a 4 12 roof slope. Load tables are available for all fabral panels. 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. The table shows one 2 x 8 that will make a 15ft.

For more detailed information on re roofing applications consult fabral tech nical bulletin 721 re roofing with metal. 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. 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. Purlin spacing is dependent on profile of the metal and gauge plus snow and wind load plus what the rafters are designed to carry.

I explained the layout of roof trusses and purlins on your building design. Purlins should be fastened through the decking and into the rafters. Dead load will be the actual weight of the roof steel and the roof purlins. One of my questions was about snow loads.

Rafter spacing is based on the width of the metal roofing panels. 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. Fyi we run purlins on 3 5 feet on center depending on size of purlin. The width of metal panels will determine the rafter spacing.