Create a purlin framework
Purlins can be used create a supporting framework and to transfer the loads imposed by the metal sheeting onto the primary building structure. Purlins can be fixed to rafters using boltable cleats.
As a rough guide purlins should be at least 50mm wide to ensure sheets can be easily fixed, and, in the case of 0.7mm thickness sheeting, be spaced no further than 1.2m apart. 1m apart in the case of 0.5mm thickness sheeting. Exact requirements will vary.
All purlin joins or laps should be supported by a rafter.
Once purlins have been fitted and a supporting framework created an inspection should be carried out before further work. Amongst other things, It should be checked that:
- the purlin framework is correctly aligned and levelled;
- purlins are correctly spaced and within specified tolerances;
- there are no protrusions e.g. bolt heads on the face of the framework.
Z Section Purlins
We now produce metal Z section purlins in Z39 structural grade galvanised steel. These are available with a 140mm, 175mm or 200mm depth Z section and in 1.6mm, 1.8mm and 2mm thickness steel.
Z section purlins can be made to any length and can be joined by overlapping (one Z section can be turned around and slotted inside another) or by using short sleeves where two longer sections meet.