Purlin Spacing For Metal Roof

We do recommend it however.

Purlin spacing for metal roof. Standard gage are generally used for roofing. 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. Once the purlin spacing is determined then the metal roofing panels are typically attached to every line of purlins. Without a set of blueprints with a pe s seal you have no option but to follow the inspectors gig.

Here is the formula for calculation of a roof purlin. Cos of live load dead load x cos of the purlin spacing x purlin span squared 8 x sm section modulus of the member x duration of load 1 15 in areas with snowfall x cr repetitive member factor of 1 15 where members are 24 on center or less fb fiberstress required. Purlin spacing is dependent on profile of the metal and gauge plus snow and wind load plus what the rafters are designed to carry. Load tables specifying safe loads for different spans are available from metal deck manufacturers.

By the standard the most used placement of purlin span for metal roof is five foot intervals. The purlin are ultimately used to fasten the roof steel providing a diaphragm effect along with the siding when properly engineered and installed. For the lighter material such as lightweight aluminum the common spacing length is 4 inches of clear gap. Numbers 20 and 22 u s.

For 2x4s purlins the posts are spaced in 4 feet distance. If the space between posts is greater than 8 feet then brace is needed to avoid buckling. This will depend upon the type of panel that is used and the thickness of the steel. In many cases post frames lack structural sheathing so the roof panels will need to span between the supporting purlins or trusses.

For 2x6s purlins the posts are spaced in 6 feet distance. Fyi we run purlins on 3 5 feet on center depending on size of purlin. Metal roofing gauges can be a complicated topic so we get asked tons of questions by people. The spacing of purlins on roofs and girts on wall is usually 4 to 6 ft.

Do all roofing projects require purlins. An engineer will use a load chart in order to determine the spacing between metal purlins. Spacing is typically 24 on center in low snow loads and is reduced based upon truss span and snow load. Screw line spacing for metal roofing over metal purlins.

The typical spacing standards for residential and commercial buildings are about 1 to 2 foot. Lighter gauge panels like 22 24 and 26 gauge sheeting will remain more structurally sound for years to come. Edit answer for another 15 minute you need to check the installation instructions from the manufacturer depending on whether the purlins firring strips are 1x or 2x material and how wide thickness metal gage of roofing steel or aluminum type of seams design wind and snow loading whether designed to be walked on or not etc i have seen it vary from as little as 4 inches clear gap between firring strips on lightweight aluminum to as much as 4 feet on very heavy gage steel.