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Purlin Installation Guide

Once you’ve prepared your roofing sheets, you’ll need to know how to install purlins to create a supporting framework for your sheets to be affixed to. This type of structure also helps to transfer the loads imposed by the metal sheeting onto the primary building construction, adding structural integrity and ensuring everything stays in place. In this article, you’ll also learn how to support roof purlins to be sure your roof construction stays intact.


Purlin Spacing for Metal Roof Sheets

In order for the metal sheets to be easily fixed to the purlins they should be at least 50mm wide. When positioned, roof purlins should be spaced no further than 1.2 metres apart when using sheeting with a thickness of 0.7mm, and 1 metre when using 0.5mm sheeting. Exact requirements will vary, but as a rough guide, this is a good rule of thumb to follow. Before completing or installing any purlins, if in doubt please consult a qualified professional.

How to Support Roof Purlins

Purlins can be fixed to rafters and all joins and laps should be supported by a rafter. Once your purlins have been fitted and a supporting framework has been created, you should look to carry out an inspection before you continue work. Check the purlin framework is correct, aligned and levelled and make any adjustments if you spot an error. The purlins must be correctly spaced and within specified tolerances, or the weight of the roofing sheets could damage them and render them useless.

Z Section Purlins

Cladco Profiles now produces metal z section purlins, made with Z39 structural-grade galvanised steel. These Z Section purlins are available with a 175mm depth and a steel thickness of 1.8mm.

These purlins can be made to any length (maximum 9m) and can be joined by slotting one section inside another, or by using short sleeves where two longer sections meet.

Cladco Profiles Purlins, Fittings and Fixtures

Here at Cladco Profiles, we sell a range of purlins to help you create a structure you can rely on. Take a look at our extensive range of metal roofing sheets for inspiration. If you need further advice on building your roof, please visit our handy installation guide on our website, or alternatively, download our installation PDF. We’re always on hand to offer advice as and when you need it, please use our contact us page to get in touch, or visit our FAQs page for some queries our customers often have.