Rafter And Purlin Spacing For Metal Roof

Standard gage are generally used for roofing.

Rafter and purlin spacing for metal roof.

Purlin spacing is dependent on profile of the metal and gauge plus snow and wind load plus what the rafters are designed to carry. 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. Posted in metal roof roof types. To determine how far apart to set rafters measure the width of the metal panel and then the width of the first hill and valley of the panel.

The spacing of purlins on roofs and girts on wall is usually 4 to 6 ft. Purlin spacing for metal roofing. You have to take the width of your roofing panel into the considerations. Without a set of blueprints with a pe s seal you have no option but to follow the inspectors gig.

A metal roof must also allow for some overlap on each side of the panels which will reduce the effective width of the panel. The heavier the expected load is the shorter the distance between the purlins. Determining rafter s spacing is as important as setting the metal roof purlins spacing. However engineering determines the optimal spacing between the purlins.

Numbers 20 and 22 u s. 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. Wider panels allow for greater spacing between rafters. Load tables specifying safe loads for different spans are available from metal deck manufacturers.

Purlins are usually supported by rafter building walls or the weight of the roof deck itself. Do all roofing projects require purlins. To know more about it read the following passage below that explain it into details. Twenty four inches is a common spacing of furring strips for a metal roof.

Correctly measure the spacing of furring strips for a metal roof to further decrease condensation. Fyi we run purlins on 3 5 feet on center depending on size of purlin. The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to. 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.

The most common measurement used for rafter spacing is either 16 or 24 inches. Spacing for purlins on a standard load most designs call for purlin placement at five foot intervals. 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.