Purlin Spacing For Metal Roofs

For heavier material such as gage steel the metal roof purlins spacing length could go up to 4 feet.

Purlin spacing for metal roofs.

A metal roof must also allow for some overlap on each side of the panels which will reduce the effective width of the panel. Standard gage are generally used for roofing. The heavier the expected load is the shorter the distance between the purlins. This will depend upon the type of panel that is used and the thickness of the steel.

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. If the space between posts is greater than 8 feet then brace is needed to avoid buckling. They give added support to the roof and also provide a nailing surface for the end panels and drip edge.

Do all roofing projects require purlins. We do recommend it however. For 2x6s purlins the posts are spaced in 6 feet distance. Screw line spacing for metal roofing over metal purlins.

They are installed on top of the roof rafters with a felt underlayment or vapor barrier installed on top. The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to. By the standard the most used placement of purlin span for metal roof is five foot intervals. Numbers 20 and 22 u s.

Spacing for purlins on a standard load most designs call for purlin placement at five foot intervals. However engineering determines the optimal spacing between the 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. 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.

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. For the lighter material such as lightweight aluminum the common spacing length is 4 inches of clear gap. Wider panels allow for greater spacing between rafters.

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