Why use Z instead of C purlins?

Z purlins can be lapped over rafters to act as continuous beams, which usually saves weight on multi-bay roofs.

WS Z purlins and girts

Built for continuous roofs

Z sections have one wider and one narrower flange so two sections nest into each other at laps over the rafters. Lapped Z purlins act as continuous beams – lighter purlins for the same span, the standard secondary system for pre-engineered buildings.

C and Z purlin section dimensions — Section parameters H, E, F, L, lip angle and hole centres K.

Standard sizes (mm)

WS Z purlins – standard sizes
No.	Type	H	E	F	L	T	Lip angle	K (holes)
1	Z125	125	52	58	16–20	1.2–3.0	95–115	50–55
2	Z150	150	52	58	16–20	1.2–3.0	95–115	50–80
3	Z175	175	52	58	16–20	1.5–3.0	95–115	50–90
4	Z200	200	52	58	16–20	1.5–3.0	95–115	50–120
5	Z175	175	62	68	16–20	1.5–3.0	95–115	50–90
6	Z200	200	62	68	16–20	1.5–3.0	95–115	50–120
7	Z250	250	62	68	16–20	1.5–3.0	95–115	50–160
8	Z200	200	72	78	16–20	1.5–3.0	95–115	50–120
9	Z250	250	72	78	16–20	1.5–3.0	95–115	50–160
10	Z300	300	72	78	16–20	1.5–3.0	95–115	50–210

Auto-size Z line: H 100–400 mm, E / F 50–130 mm, L 15–25 mm, T 1.2–4.0 mm, lip 95–115°, K 40–320 mm. Holes: oval 14 × 22 mm or 16 × 24 mm.

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