Steel Roof Purlin Span

Homepage metal roof metal roof purlins spacing and rafter distance details by rooflast posted on june 29 2020 june 29 2020 during the roof installation or re roofing process after the roof sheets are prepared it is time to support their framework by installing purlins.

Steel roof purlin span.

The purlin are ultimately used to fasten the roof steel providing a diaphragm effect along with the siding when properly engineered and installed. Steel roof purlins and wall girts are produced and available in house. Spacing is typically 24 on center in low snow loads and is reduced based upon truss span and snow load. The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to.

These tables are for spans in which purlins are lapped over each support where the lap length is 15 of the span. Tables are given for 5 or more spans. Max roof span allowed 12m. The safe spans below are suitable for sheds and class 1 structures with the following assumptions.

Contact flexospan for information on custom purlin and girt structural steel dimensions. Purlins near roof edges or changes of roof slope are subject to higher wind forces than interior purlins. The topic we want to discuss today is the purlin installation. All spans to have 1 row of bridging.

High pressure zones kl 1 5 and 2 0 included. Engineered purlin metal mart offers a complete line of engineered purlin material. Dead load will be the actual weight of the roof steel and the roof purlins. Cleated or bracketed fixing only no flange bolting.

To identify whether yours is the earlier or the latter type look for the end of the rails and check whether the shapes mimics the shape of letter c or letter z. For sake of discussion we will assume a minimal roof snow load of 20 psf pounds per square foot and a 4 12 roof slope. The cos of the purlin spacing is because the load on the purlins is vertical and the purlin spacing is with the run of the roof. 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.

Steel z purlins and z girts are also available with other depths and flange widths. Safe roof purlins spans. We manufacture any component from 1 2 steel subgirts to 12 section up to 10 gauge. As per as1684 and as4055 spanman adopts a nett pressure coefficient applied along the full length of the purlin of cpn 2 0 for non cyclonic zones n1 to n6 and cpn 2 5 for cyclonic zones c1 to c4.

Continuous purlin span are simply supported at each end and at a series of equally spaced intermediate supports.