Long Span C Purlin Roof Design

Use recommended minimum roof pitches as specified by roof sheet supplier.

Long span c purlin roof design.

Safe roof purlins spans. Four or more equi spaced supports. C purlin and c girt structural steel wind snow weight tables. Maximum roof slope is 5 for monoslope and 22 5 for pitched roof.

The spacing of purlins usually call for careful arrangement in the sense that it should follow the nodal pattern of the supporting trusses. Spantec has prepared these tables for use by people skilled in the design and specification of the. If a steel purlin must span 24 feet between girders it should be at least 12 deep for girders calculate 3 4 inch of depth for every foot of span. The standard of purlin length will vary anywhere between 100 to 300 mm while the thickness will vary anywhere between 1 to 3 mm.

The number of supports beams or purlins affects the allowable span length. C purlins and c girts. High pressure zones kl 1 5 and 2 0 included. Cpe 0 9 and cpi 0 2.

Tables are given for 5 or more spans. The c sections can also form part of the columns and rafters in these smaller applications. Flexospan provides standard even profile c purlins and c girts as well as custom profiles and punching patterns. The safe spans below are suitable for sheds and class 1 structures with the following assumptions.

For purlins calculate 1 2 inch of depth for every foot of span. 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. We manufacture any component from 1 2 steel subgirts to 12 section up to 10 gauge. For 2x4s purlins the posts are spaced in 4 feet distance.

Max roof span allowed 12m. Monoslope pitched single. This post will be focusing on design of steel purlin using cold formed sections. For outwards loads on equal continuous spans the bridging shown is required in the end spans.

These tables are for spans in which purlins are lapped over each support where the lap length is 15 of the span. Continuous purlin span are simply supported at each end and at a series of equally spaced intermediate supports. Two supports one at each end double span. Flat roof span tables allow for a maximum roof pitch of 5º.

If you want to know how to support roof purlins they are usually supported by 2 4 or 2 6 struts or posts. Arrangement of purlins by default purlin sections assume the slope of the roof they are supporting. Data is given in each table for. Purlins rails eaves beams z e d p u r l i n s y s t e m s e a v e s be a m s z e d c e e s h e e t i n g r a i l s fl o o r c e e s design guide september 2014.

Three equi spaced supports equal spans.