Span C Purlin Roof Design

In timber construction purlins are nailed to the rafter or supporting trusses while in steel roof construction they are welded or bolted to the rafters or trusses by the means of cleats.

Span c purlin roof design.

Roof purlin are members used to directly support roof sheeting materials and could be made of timber or steel. These tables are for spans in which purlins are lapped over each support where the lap length is 15 of the span. Maximum roof slope is 5 for monoslope and 22 5 for pitched roof. In general c purlins sheds are best for smaller spans.

However some manufacturers sell designs to do up to 24 metres in span. Maximum span design moment m ed 2 31. Of a fascia purlin in fascia applications. This is slightly smaller than the centre to centre of the rafters.

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. Continuous purlin span are simply supported at each end and at a series of equally spaced intermediate supports. This is right at the limit of a purlin s capacity and does no leave much margin for coping with nasty weather conditions. This design usually involves a lot of extra bracing.

Three equi spaced supports equal spans. For outwards loads on equal continuous spans the. Monoslope pitched single. 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.

Two supports one at each end double span. Four or more equi spaced supports. Where purlin spans are unequal between supports each purlin should have 6 25 of each adjacent span added not 6 25 of that purlin s span. 20 95 30 d c a b variable angle 18 x 22 holes 34 x 10 recess upturned lip z sections standard z the following diagrams and tables illustrate the sizes and thicknesses readily available for.

How far can c purlins span. Meanwhile there are two kinds of purlin span for metal roof based on the shapes which are the c purlins and z purlins. Design specification data section z or c thickness mm yield stress mpa mass kg m 75 95 0 95 550 1 26 75 12 1 2 500 1 59 75 15 1 5 450 1 97 100 10 1 0 550 1 77 100 12 1 2 500 2 10 100 15 1 5 450 2 61. The c section can be supplied as a standard configuration or with the top flange bent to suit the roof slope.

Versus the size centers of the purlins bridging and connection details. Where lapping occurs it is the centre line of the lap. The number of supports beams or purlins affects the allowable span length. Data is given in each table for.