Rafter And Purlin Spacing For Metal Roof

The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to.

Rafter and purlin spacing for metal roof.

We do recommend it however. Contact fabral for additional information. 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. Purlins should be fastened through the decking and into the rafters.

The inspector asked about the type of wood being used as purlins. The table shows one 2 x 8 that will make a 15ft. Purlin spacing is dependent on profile of the metal and gauge plus snow and wind load plus what the rafters are designed to carry. The width of metal panels will determine the rafter spacing.

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. 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. I explained the layout of roof trusses and purlins on your building design. A metal roof must also allow for some overlap on each side of the panels which will reduce the effective width of the panel.

Load tables are available for all fabral panels. One of my questions was about snow loads. Do all roofing projects require purlins. 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.

Without a set of blueprints with a pe s seal you have no option but to follow the inspectors gig. For more detailed information on re roofing applications consult fabral tech nical bulletin 721 re roofing with metal. 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. This will provide a solid framework for attaching the metal panels.

Rafter spacing is based on the width of the metal roofing panels. There is a chance of damaging roofing sheets if you are failed to do so. Wider panels allow for greater spacing between rafters. I did not know.

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. The metal roof purlins spacing must be done correctly within narrow tolerances. The wider the roofing panels the greater spacing distance you should put. 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.