Z Purlin Carbon Steel Section — Factory Direct Supplier | Huaxia-Steel

Z purlins are the cold-formed Z-shaped sections that span between portal frames and carry roofing and cladding in modern steel buildings. Their Z profile laps cleanly over consecutive bays, giving continuous multi-span strength with lighter steel than plain channels, which is why they dominate purlin supply for warehouses, workshops and industrial roofs. We manufacture Z purlin sections from 140 mm to 300 mm depth in gauges from 1.5 mm to 3.0 mm, roll-formed from G250–G450 grade coil, punched and cut to your length.

Because purlins are a building-system component, the details decide the price of the whole package: hole pitch, lap strategy, coating type and bundle configuration. We quote and produce against your engineering layout, delivering bundle-marked, per-length-cut sections ready for your erection crew — with export container packing that keeps straightness through sea transit.

Product Overview

Our Z purlins are roll-formed from pre-galvanized, galvanized (Z275–Z600) or black (uncoated, primer-ready) carbon steel coil. The profile is produced on a dedicated purlin line with inline pre-punching for bolted connections to cleats, bridging and cladding rails. Standard lip dimensions are matched to the section depth so the lip stiffening works as designed.

Two geometries are available: plain Z sections and lappable (curved-corner) Z sections with reduced flange width on one side so consecutive purlins nest tightly at laps. For most multi-span roofs the lappable version is specified because it restores continuity across supports and cuts steel weight significantly against single-span design.

Dimensions and Tolerances

Parameter	Range	Tolerance / Note
Section depth	140 / 200 / 250 / 300 mm	±1.5 mm
Flange width	55–75 mm	per depth class
Thickness (gauge)	1.5–3.0 mm	±0.10 mm
Length	up to 12 m	±2 mm cut accuracy
Hole pitch	custom	±1.5 mm with inline punching
Weight per metre	2.5–10.5 kg/m	per depth and gauge

Sections are punched to your cleat pattern — standard 18 mm or 22 mm bolt holes at 100 mm centres are common, but any layout is produced from a drilling schedule. Bundles are collated so each bay’s sections arrive together, labelled by length and location, which cuts on-site sorting dramatically.

Material Grades and Coatings

Option	Grade / Coating	Typical use
Pre-galvanized	G250–G300, Z275–Z450	Standard internal roofs
Hot-dip galvanized after forming	Z600 coating per ISO 1461	Corrosive / coastal sites
Black steel + primer	G350 structural	Internal, to be top-coated
High-strength	G450 / S550GD	Long spans, weight-optimised

Yield strength ranges from 250 MPa (G250) to 450 MPa (G450). High-strength G450 allows lighter gauges for the same load, which saves freight — often the deciding factor on export projects where purlin weight drives container count.

Manufacturing Standards

• AS/NZS 4600 — cold-formed steel structures (design basis for lappable systems).
• EN 10346 — continuously hot-dip coated steel flat products (G-grades, S550GD).
• ASTM A653 — hot-dip galvanized coil specification for export to US-spec projects.
• ISO 1461 — hot-dip galvanizing after fabrication for post-formed coating.
• ISPM 15 — timber dunnage compliance for export packing.

Design assistance is available: send the roof plan, span and load case and we will return a purlin schedule with depths, gauges, bridging positions and per-length cutting list — the document your erector and your quantity surveyor both work from.

Applications

• Roof purlins for warehouses, logistics centres and manufacturing plants.
• Wall girts supporting cladding on portal frame buildings.
• Mezzanine floor joists in light-duty systems.
• Canopy and carport framing kits.
• Solar farm mounting rails where high-strength light gauges pay back freight.

Lapped multi-span Z systems are the standard because they cut total steel weight 15–25% against single-span channels at the same load — worth confirming with your engineer before defaulting to a heavier plain section.

Quality Assurance

• Coil mill certificates traceable to each production run; coating weight certificates for Z-coils.
• Section dimensional checks: depth, flange, thickness and lip per shift with recorded results.
• Hole pitch and gauge verification against the approved drilling schedule.
• Galvanizing adhesion and coating weight checks (magnetic gauge) per batch.
• Bundle marking: length, section, quantity and location code for site sorting.
• Third-party inspection arranged before shipment on request.

Packaging and Export Shipping

Purlins bundle at 2–4 t with steel strapping and timber separators that protect coatings from strapping damage; each bundle is labelled with section, length and quantity. Standard container lengths up to 5.8 m load in 20 ft and 40 ft units with dunnage; longer sections ship in 40 ft open-top containers or flat racks.

We ship FOB, CFR and DAP worldwide with typical production lead time of 2–4 weeks from approved drawings. Send your purlin schedule (or roof layout) with destination port and we will return a firm quote including freight within 24 hours.

Z Purlin vs C Purlin: Where Each Wins

Aspect	Z purlin	C purlin
Multi-span lapping	Excellent — nests at laps	Poor — cannot lap effectively
Single-span use	Good	Good
Weight efficiency (multi-span)	15–25% lighter	Baseline
Typical role	Roof purlins, long runs	Wall girts, framing, eaves struts
Stacking for transport	Nested within same depth	Nested face-to-face

The engineering logic: a Z section lapped over a support behaves as a continuous beam, cutting the mid-span moment that governs single-span design. That is why long roof runs use Z and why C sections concentrate in wall girts, door frames and short spans where lapping adds nothing. Most buildings mix both — Z on the roof, C at walls and trim — and we supply the pair from one production line so hole patterns and coatings match across the building.

Bridging, Cleats and System Accessories

Purlins are a system, not a section. Bridging (bolted channel or proprietary strutting) restrains the compression flange between restraints and is placed per the design schedule; cleats connect purlins to frames and transfer the load. We manufacture cleats from the same grade family and punch purlins to the cleat hole pattern, so the bolted connection assembles on site without re-drilling — the single most common site complaint when purlins and cleats come from different sources.

Ordering the system together also fixes the lap schedule: purlin lengths are cut so laps land on frames, not in spans, which requires the erection layout before production. Buyers who send the final layout avoid the classic waste of uniform-length purlins cut for a different frame spacing.

Load Selection and Span Practice

Purlin selection balances three loads: dead load (cladding, services), live load (maintenance and environmental) and uplift from wind, which often governs the bridging and cleat design rather than the section itself. Standard span tables for our sections cover the common 6–9 m frame spacings with 1.5–3.0 mm gauges; beyond that, a short design note from your engineer converts the load case into a depth and gauge quickly.

Two cost levers are worth knowing. First, higher-strength G450 coil lets lighter gauges carry the same load, saving steel and freight on long-span roofs. Second, optimizing the lap schedule can drop a gauge size in end bays. Both levers are free — they just require the design to be sent to the manufacturer before the order instead of after.

Coating Selection for Service Life

Coating choice should match the building’s life expectation and environment: Z275 pre-galvanized coil suits dry internal environments with a top-coated roof, Z450–Z600 suits humid or coastal sites, and hot-dip galvanizing after forming suits heavily corrosive plants where the coating must reach cut edges and punched holes. Because punching opens bare edges in pre-galvanized coil, aggressive environments justify the post-forming galvanizing premium — the coating wraps every surface including holes.

Ordering Workflow and Lead Times

Purlin production runs from an approved section and hole schedule: send the layout, we return a schedule for sign-off, and production takes 2–4 weeks from approval. Container-optimized cutting (lengths up to 5.8 m for 20 ft, up to 11.8 m in open-top) is planned at scheduling, so tell us the destination port early — recutting after production wastes both material and schedule.

Mixed orders — Z roof purlins plus C wall girts, cleats and bridging from the same line — ship in one container set with hole patterns matched, which is how most warehouse projects order from us.

Huaxia-Steel roll-forms Z purlins, C sections, cleats and bridging on dedicated lines with inline punching, so your whole light-steel framing package arrives as one matched system. Send your roof and wall layout with destination port — we will return a purlin schedule and a firm container-by-container quote within 24 hours.

Export projects account for the majority of our purlin volume, so the practical details are already engineered in: container-optimized lengths, bundle weights matched to destination crane limits, coating selection advised against the site’s corrosion category, and spare sections included for site damage allowance. One purchase order covers sections, accessories and the schedule that ties them together.

Ask also about mixed-depth bundles: many roofs use a heavier section in end and penultimate bays and a lighter gauge in interior bays. Producing both depths in one production run, cut to their respective span schedules, captures that weight saving without splitting the order across suppliers.