Purlin Spacing For Metal Roofs

Purlins are 2 by 4 feet and are installed much like metal roofing.

Purlin spacing for metal roofs.

The heavier the expected load is the shorter the distance between the purlins. They give added support to the roof and also provide a nailing surface for the end panels and drip edge. The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to. An engineer will use a load chart in order to determine the spacing between metal purlins.

Load tables specifying safe loads for different spans are available from metal deck manufacturers. 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. Wider panels allow for greater spacing between rafters. For 2x6s purlins the posts are spaced in 6 feet distance.

Metal roof purlins are installed horizontally under metal roofs. Spacing for purlins on a standard load most designs call for purlin placement at five foot intervals. For heavier material such as gage steel the metal roof purlins spacing length could go up to 4 feet. If the space between posts is greater than 8 feet then brace is needed to avoid buckling.

By the standard the most used placement of purlin span for metal roof is five foot intervals. Numbers 20 and 22 u s. Once the purlin spacing is determined then the metal roofing panels are typically attached to every line of purlins. However engineering determines the optimal spacing between the purlins.

Standard gage are generally used for roofing. The spacing of purlins on roofs and girts on wall is usually 4 to 6 ft. They are installed on top of the roof rafters with a felt underlayment or vapor barrier installed on top. The typical spacing standards for residential and commercial buildings are about 1 to 2 foot.

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. However it is important to note that expected load is a crucial factor while determining this. For the lighter material such as lightweight aluminum the common spacing length is 4 inches of clear gap. Screw line spacing for metal roofing over metal purlins.

Do all roofing projects require purlins.