Rafter And Purlin Spacing For Metal Roof

The width of metal panels will determine the rafter spacing.

Rafter and purlin spacing for metal roof.

Screw line spacing for metal roofing over metal purlins. To know more about it read the following passage below that explain it into details. There is an available purlin for every type of roofing material including purlin span for metal roof which is the most common material type to use this item. This will depend upon the type of panel that is used and the thickness of the steel.

Load tables are available for all fabral panels. 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. Once the purlin spacing is determined then the metal roofing panels are typically attached to every line of purlins.

Maximum rafter spans for a patio roof in areas with mild climates patio roofs are generally designed for loads of 30 psf pounds per square foot. 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. Purlins are usually supported by rafter building walls or the weight of the roof deck itself. Without a set of blueprints with a pe s seal you have no option but to follow the inspectors gig.

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. We do recommend it however. 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. Fyi we run purlins on 3 5 feet on center depending on size of purlin.

The wider the roofing panels the greater spacing distance you should put. There is a chance of damaging roofing sheets if you are failed to do so. 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.

For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements. Dead load will be the actual weight of the roof steel and the roof purlins. For more detailed information on re roofing applications consult fabral tech nical bulletin 721 re roofing with metal. An engineer will use a load chart in order to determine the spacing between metal purlins.

Purlin spacing is dependent on profile of the metal and gauge plus snow and wind load plus what the rafters are designed to carry. 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 should be fastened through the decking and into the rafters. The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to.