What is a Z-section?
A Z-section is a beam or strip, usually steel, whose cross-section has the shape of a Z. It consists of a web with a flange at the top and bottom pointing in opposite directions.
Uses
- Roof purlins in steel-framed buildings, carrying profiled sheets or sandwich panels between the rafters.
- Side rails between columns for fixing wall cladding.
- Sub-frames and fixing profiles.
Most Z-purlins are cold-formed from galvanised strip steel, so they are light for their load capacity.
Why a Z-shape?
- Lapping over supports: two Z-sections nest into each other. Lapping them over a rafter creates a continuous beam with less deflection.
- Wide flange for fixing panels.
- Nestable for transport and storage.
Installation tips
- Prevent twisting: Z-sections tend to rotate or buckle sideways under load. Sheeting, sag rods or bracing must restrain them as specified by the supplier.
- Flange direction: follow the erection drawings.
- Lap length and bolts: as specified by the engineer or manufacturer.
- Cut edges: touch up with zinc-rich paint.
Related terms
- Wind bracing
- Purlin
- Tie plates
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