Fixings and accessories
Purlins and rails
Steel purlins and side rails
Purlins carry the roof sheets or panels across the rafters, and side rails carry the wall cladding. We supply galvanised steel Z and C sections with the cladding that goes on them, so the frame and the skin come from one order.
- Z and C sections
- Roof purlins and side rails
- Galvanised steel
- With the cladding that goes on them
Z or C sections
Z sections are the usual choice for roof purlins, as they can be joined over the rafters to work as one continuous run across several bays. C sections are used for shorter single spans, trimming around openings and framing.
Sleeved and butt systems
On buildings with several bays, purlins are usually sleeved over the supports so they act as continuous beams. In a butt system each purlin stops at the rafter, which suits odd layouts and single bays. Side rails work the same way on the walls. Both are cold-rolled from galvanised steel, in a range of depths and thicknesses.
Sizing
Purlin size and spacing depend on the span, the roof loads and the sheet or panel. Send us the frame drawings and we'll quote to the engineer's specification.
Questions we’re asked
What is the difference between Z and C purlins?
Z purlins can overlap or be sleeved at the supports to run continuously over several spans, which suits roofs. C purlins are often used for shorter spans, side rails and framing openings. The engineer's design decides which.
How far apart should purlins be?
It depends on the roof loads and on the sheet or panel being used, which has a maximum span. Follow the engineer's design and the sheet manufacturer's span tables.
UK manufactured
