Purlins provide support to the rafters in a traditional roof construction. They are either positioned at the ridge, or along the slope of the rafters, or sometimes both.

Purlins are usually timber, but once their span is over around 4m, then steel sections are normally more economical.

We need the following information to design roof purlins:

the distance between the front and rear walls of the property

the distance between the side walls of the property

the approximate height of the roof above eaves level

the span of the purlins

the type of roof covering.

the approximate location of the building

All design work is carried out in accordance with BS5268 (The structural use of timber).

The calculations provided will be suitable for Building Regulation approval.