What is a purlin, and C or Z?
Purlins are the secondary members that span between rafters and carry the roof sheeting; girts do the same on walls. Cold-formed galvanized C and Z sections replaced hot-rolled channels because they weigh 30–40% less for the same span and arrive punched and galvanized. Z purlins nest: overlapped over the rafter they form a continuous beam that carries 15–25% more load than a simple span, which is why Z is the choice for long roofs on pre-engineered buildings. C purlins are symmetric, easier to detail at gables, cladding rails and eaves, and are used in single spans, as girts, and wherever the section must be flush. Both are lipped (return flanges) for stiffness; unlipped U purlins are for light applications.
Profile pages
Each purlin type has its own page with section table, kg/m, span guide and system details: C purlins for single spans, girts and framing, and Z purlins for lapped and sleeved continuous roofs. Battens and sub-frames are covered by the omega profile.
Section table — Z purlins
| Section | Depth (mm) | Thickness (mm) | kg/m | Ix (cm⁴) | Wx (cm³) | Typical span* |
|---|---|---|---|---|---|---|
| Z100 × 1.5 | 100 | 1.5 | 2.9 | 58 | 11.6 | 3.0 m |
| Z120 × 1.5 | 120 | 1.5 | 3.2 | 92 | 15.3 | 3.5 m |
| Z150 × 1.5 | 150 | 1.5 | 3.6 | 163 | 21.7 | 4.5 m |
| Z150 × 2.0 | 150 | 2.0 | 4.8 | 215 | 28.7 | 5.0 m |
| Z175 × 2.0 | 175 | 2.0 | 5.2 | 310 | 35.4 | 5.5 m |
| Z200 × 2.0 | 200 | 2.0 | 5.6 | 437 | 43.7 | 6.0 m |
| Z200 × 2.5 | 200 | 2.5 | 7.0 | 543 | 54.3 | 6.5 m |
| Z250 × 2.5 | 250 | 2.5 | 8.0 | 907 | 72.6 | 7.5 m |
| Z250 × 3.0 | 250 | 3.0 | 9.6 | 1 083 | 86.6 | 8.0 m |
| Z300 × 3.0 | 300 | 3.0 | 10.8 | 1 700 | 113 | 9.0 m |
| Z350 × 3.0 | 350 | 3.0 | 12.0 | 2 500 | 143 | 10 m |
* purlin spacing 1.5 m, roof load 1.0 kN/m² (dead + live/wind), continuous overlapped system, deflection L/200. Guide only — designed per EN 1993-1-3 by the engineer.
Section table — C purlins
| Section | Depth | Thickness | kg/m | Ix (cm⁴) | Wx (cm³) | Simple span* |
|---|---|---|---|---|---|---|
| C100 × 1.5 | 100 | 1.5 | 2.9 | 57 | 11.4 | 2.5 m |
| C120 × 1.5 | 120 | 1.5 | 3.2 | 88 | 14.7 | 3.0 m |
| C150 × 1.5 | 150 | 1.5 | 3.6 | 150 | 20.0 | 3.5 m |
| C150 × 2.0 | 150 | 2.0 | 4.8 | 197 | 26.3 | 4.0 m |
| C175 × 2.0 | 175 | 2.0 | 5.2 | 290 | 33.1 | 4.5 m |
| C200 × 2.0 | 200 | 2.0 | 5.6 | 410 | 41.0 | 5.0 m |
| C200 × 2.5 | 200 | 2.5 | 7.0 | 510 | 51.0 | 5.5 m |
| C250 × 2.5 | 250 | 2.5 | 8.0 | 860 | 68.8 | 6.5 m |
| C250 × 3.0 | 250 | 3.0 | 9.6 | 1 020 | 81.6 | 7.0 m |
| C300 × 3.0 | 300 | 3.0 | 10.8 | 1 600 | 107 | 8.0 m |
* simply supported, 1.5 m spacing, 1.0 kN/m², L/200. Section properties vary slightly with flange width; exact values on the datasheet.
Continuous systems: sleeved and overlapped
Z purlins are supplied overlapped (300–600 mm lap over the rafter, bolted through the web) or with sleeves (short heavier Z pieces at each support) to act as continuous beams. Overlapped Z is the economical standard; sleeved is used where all purlins must be the same length. C purlins are single-span with butt joints on cleats, or sleeved for continuity. Our drawing office prepares the punching layout from the fabricator's frame drawings — hole positions for cleats, laps, sag rods, bridging and sheeting rails — so every piece arrives labelled by grid line.
Material and coating
| Grade | Yield | Coating | Where |
|---|---|---|---|
| S280GD+Z275 | 280 MPa | Zinc 275 g/m² | Standard EU / Balkan buildings |
| S350GD+Z275 | 350 MPa | Zinc 275 g/m² | Export standard — Gulf, Africa, CIS (lighter sections) |
| S450GD+Z275 | 450 MPa | Zinc 275 g/m² | Long spans, high wind/snow |
| S350GD+ZM250 / ZM310 | 350 MPa | Zinc-magnesium | Solar structures, coastal, 25-yr warranty |
| Black (S235JR HRPO) + paint / HDG | 235–355 | Painted or hot-dip after forming | Heavy 3–4 mm girts, painted structures |
Accessories
- Purlin cleats (welded to rafters or bolted), 3–6 mm galvanized
- Sleeves for continuous Z/C systems
- Sag rods Ø12–16 mm with nuts, or galvanized bridging channels
- Eaves struts, apex ties, sheeting rails and fly bracing
- Bolts M12 8.8 galvanized, self-drilling screws for sheeting
- Matching trapezoidal or corrugated sheet and flashings from the same plant
Purlin price per ton and per metre
Purlins are priced per ton (or per metre) from the galvanized strip band plus roll-forming and punching: as a guide S350GD+Z275 purlins sit 12–20% above the pre-galvanized hollow-section band on the hollow sections page; ZM adds 8–15%. Firm price per punched drawing within one working day.
Bands from our weekly export list (September 2026), FOB Istanbul, full-container quantities, excluding freight and certificates. Firm price per project on RFQ within one working day.
Export and packing
Nested bundles of 20–40 purlins (0.5–1.5 t), strapped on bearers, labelled by grid line; up to 11.8 m in a 40' HC (about 20–24 t), 13.5 m by truck or flat-rack. HS code 7216.61 (cold-formed sections from flat-rolled products).
| Term | Detail |
|---|---|
| MOQ | 1 truck or 1 × 40' HC (≈ 20–24 t); sections mixed |
| Incoterms | FOB Istanbul · CIF / CFR Gulf, Africa · DAP EU, Balkans, Iraq, Caucasus · DAP Aktau / Almaty |
| Lead time | 10–15 working days from drawing approval |
| Packing | Nested bundles 0.5–1.5 t on bearers, strapped, labelled by grid line |
| Container / truck | 40' HC ≈ 20–24 t (≤ 11.8 m) · truck 22–24 t (≤ 13.5 m) |
| Documents | Invoice, packing list per bundle, EN 10204 3.1, punching drawings, CE (EN 1090) on request, certificate of origin |
| Payment | 30% advance, balance against B/L copy; L/C at sight via London office |
Certificates
EN 10204 3.1 for the strip (grade, zinc mass), our dimensional record, CE declaration under EN 1090-1 (EXC2) for structural purlins on request, certificate of origin; SASO, SONCAP, COC, EAC arranged.
How to order
Send the frame drawings or a purlin schedule (section, thickness, length, hole pattern, quantity), grade and coating, and port. We return the punching drawing for approval, then quote per ton and per metre with bundle plan and lead time (10–15 working days).
Standards
- EN 1993-1-3 (design of cold-formed members)
- EN 10346 (S280GD / S350GD / S450GD + Z275 or ZM)
- EN 10162 (cold-rolled sections, tolerances)
- AISI S100 / ASTM A653 (Gulf / US-spec projects)
- BS 5950-5 (legacy Gulf specs)
- EN 1090-1/-2 (CE for structural components)
Grades
Grade data sheets (chemistry, mechanicals, equivalents) are on our reference site: S250GD · S350GD · DX51D
Frequently asked questions
What is a purlin used for?
To carry the roof sheeting between rafters (and, as girts, the wall cladding between columns). Cold-formed galvanized C and Z purlins are the standard in pre-engineered steel buildings.
What is the difference between C and Z purlins?
Z purlins nest and overlap over the rafter to form continuous beams — lighter for long roofs; C purlins are symmetric, easier at gables and as girts, used in single spans. Same material and cost per ton.
Are purlins load-bearing?
Yes — they carry the roof or wall cladding plus wind, snow and maintenance loads to the main frame and are designed to EN 1993-1-3 or AISI S100; they are not primary structure.
What purlin sizes are available?
C and Z from 100 to 350 mm deep, 1.5–3.0 mm thick, 3–13.5 m long, in S280GD–S450GD Z275 or ZM; the section tables above list masses and typical spans.
Why is it called a C purlin?
Because its cross-section is a C: web, two flanges and inward lips. Z purlins are Z-shaped with flanges pointing opposite ways, which is what lets them nest.
Do you punch the holes?
Yes — cleat, lap, sag-rod and bridging holes to the fabricator's drawing on the line; every piece is labelled by position.
What is the price of purlins per ton?
Galvanized strip band plus forming and punching: about 12–20% above pre-galvanized hollow sections per ton. Firm price per drawing within one working day.
Do you manufacture purlins yourself?
Yes — roll-formed and punched on our own lines in Dilovası from our galvanized coil stock; roofing sheet and cleats come from the same plant.