Purlin Spacing For Metal Roofs

The typical spacing standards for residential and commercial buildings are about 1 to 2 foot.

Purlin spacing for metal roofs.

By the standard the most used placement of purlin span for metal roof is five foot intervals. They are installed on top of the roof rafters with a felt underlayment or vapor barrier installed on top. Load tables specifying safe loads for different spans are available from metal deck manufacturers. For the lighter material such as lightweight aluminum the common spacing length is 4 inches of clear gap.

We do recommend it however. Standard gage are generally used for roofing. Wider panels allow for greater spacing between rafters. For 2x6s purlins the posts are spaced in 6 feet distance.

This will depend upon the type of panel that is used and the thickness of the steel. Spacing for purlins on a standard load most designs call for purlin placement at five foot intervals. They give added support to the roof and also provide a nailing surface for the end panels and drip edge. Purlins are 2 by 4 feet and are installed much like metal roofing.

An engineer will use a load chart in order to determine the spacing between metal purlins. For heavier material such as gage steel the metal roof purlins spacing length could go up to 4 feet. 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. Metal roof purlins are installed horizontally under metal roofs.

Numbers 20 and 22 u s. 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 purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to. The heavier the expected load is the shorter the distance between the purlins.

However it is important to note that expected load is a crucial factor while determining this. Once the purlin spacing is determined then the metal roofing panels are typically attached to every line of purlins. 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 engineering determines the optimal spacing between the purlins.

Do all roofing projects require purlins.