Cold-formed Z section
Z purlins for lapped, continuous roof runs
A Z purlin has its two flanges pointing in opposite directions. That lets the end of one purlin sit inside the next where they meet over a rafter, so a line of Z purlins overlaps and works as one continuous member along the shed.
We roll them from 1.2 to 3.0 mm thick with a web of 100 to 300 mm, punch the holes to your drawing and cut each piece to length, up to 12 m.
Where Z purlins go
Z purlins are used where the roof runs over several frames and the engineer wants the purlins to work together. At each rafter the two purlins overlap by a set length and are bolted through, which spreads the load across the joint. On a long shed with many bays this usually allows a lighter section than a C purlin doing the same job, so the steel weight comes down.
- Roof purlins on warehouses, factory sheds and PEB buildings with several bays.
- Wall girts on long side walls, lapped at the columns in the same way.
- Reroofing jobs where old purlins are being replaced bay by bay.
For single spans, canopies and cladding rails around openings, a C purlin is usually simpler. The lap length and bolt pattern come from your engineer's design, and we punch to it.
Specifications
| Thickness | 1.2 to 3.0 mm |
|---|---|
| Web depth | 100 to 300 mm |
| Flange width | 40 to 80 mm |
| Lip | 12 to 30 mm, at 45° to the flange |
| Material | MS HR, CR, galvanised, galvalume or POSMAC |
| Steel grade | 245 to 350 MPa yield |
| Punching | Web slotted or round (×2), centre web round, flange round or manual |
| Maximum length | 12 m |
| Documents | Mill test certificate of the coil with the consignment |
A correction to our old spec sheet
The Z purlin specification on our previous website was headed "C purlin". The figures above are the Z purlin figures from our own specification (1.2 mm minimum thickness, 100 mm minimum web and lips at 45°). If you saved the old page, please use this one.
How we supply them
- Cut to length from your cutting list, with the lap already allowed for in each length.
- Punched to drawing, including the lap bolt holes, so the two ends line up over the rafter without drilling on the roof.
- Bundled and marked with the member number from your drawing.
- Delivered in lengths up to 12 m by road, with the coil's mill test certificate.
For Varun Beverages at Kosi we made and delivered purlins and ridge frames in 2.5 days after a key vendor defaulted, marked for direct installation. Read the Varun Beverages job.
What to send for a quote
Z purlins are priced per kg. Send the section (web, flange, lip), the gauge, the lap length, the hole positions, the lengths and the quantity of each, or the drawing that shows them. With only a shed size we can suggest a layout for your engineer to check.
We do not roll Z purlins thinner than 1.2 mm. We do not publish load tables for them either: the section and gauge come from your engineer's design, and we roll to it.
Send the Z purlin drawing with the lap details and we will price it by weight.
Get a quoteQuestions buyers ask us
Why use a Z purlin instead of a C purlin?
Z purlins can be lapped. One end nests inside the next over the rafter, so the run acts as one continuous member and can often be a lighter section on a long shed. For single spans a C purlin is usually simpler.
What sizes of Z purlin do you roll?
Thickness 1.2 to 3.0 mm, web 100 to 300 mm, flange 40 to 80 mm and lips of 12 to 30 mm turned at 45°. Give us the exact section from your drawing.
How long should the lap be?
Your engineer sets the lap length and bolt pattern in the design, based on the span and load. We allow for it in the cut lengths and punch the lap holes to match.
What is the longest Z purlin you supply?
12 m in one piece. Longer runs are made by lapping over the frames, which is what Z purlins are designed for.
Can I get Z purlins in galvanised or galvalume?
Yes. We roll them in HR, CR, galvanised, galvalume and POSMAC steel, from 245 to 350 MPa.