What is C purlin?
A C purlin is a cold-roll-formed lipped channel: a web, two equal flanges and two inward-turned lips that stiffen the flange edges so that a 2 mm sheet can carry a roof. It is made by passing pre-galvanized strip (S280GD or S350GD to EN 10346, zinc Z275) through a train of forming rolls at room temperature — no welding, no heat, the zinc stays intact — and punching the bolt holes in line, so each purlin leaves the mill cut to length, punched and ready to bolt. Because the section is symmetric about its web, a C purlin sits flat on a cleat and takes load through its shear centre only when restrained by the roof sheeting; it is therefore the section for simply supported spans (one purlin per bay, bolted to the rafter cleats at each end), for wall girts, eaves beams, door and window framing, mezzanine joists and any application where a channel is bolted back-to-back or to a flat plate. Its limits are the Z purlin\'s strengths: a C cannot be lapped over a support, so continuous multi-span systems, which cut purlin weight by 20–30 % on long buildings, are done in Z. We manufacture C100 to C300 in 1.5, 2.0, 2.5 and 3.0 mm, with the hole pattern, sag-rod holes and bracing cleats punched to the customer\'s drawing, in lengths 3–13.5 m.
Grades, standards and tolerances
| Grade / standard | Yield (MPa) | Note |
|---|---|---|
| S280GD+Z275 (EN 10346) | 280 | standard purlin strip; the stock grade |
| S350GD+Z275 | 350 | higher-strength purlins, longer spans |
| S450GD+Z275 | 450 | to order; maximum span per kg |
| DX51D+Z140 / Z275 | ≈ 140 (not guaranteed) | non-structural profiles only |
| Zinc Z275 | — | 275 g/m² both sides ≈ 20 µm per side; ZM on request |
Section tolerances to EN 10162; zinc Z275 gives 40–60 years indoors and 15–25 years in an unheated building envelope.
C purlin section table
| Section | Web × flange × lip (mm) | t (mm) | kg/m | Ix (cm⁴) | Wx (cm³) |
|---|---|---|---|---|---|
| C100 | 100 × 50 × 15 | 1.5 | 2.7 | 55 | 11.0 |
| C120 | 120 × 50 × 15 | 1.5 / 2.0 | 2.9 / 3.9 | 85 / 110 | 14.2 / 18.3 |
| C150 | 150 × 60 × 20 | 1.5 / 2.0 | 3.5 / 4.7 | 160 / 210 | 21.3 / 28.0 |
| C175 | 175 × 65 × 20 | 2.0 / 2.5 | 5.2 / 6.5 | 300 / 370 | 34.3 / 42.3 |
| C200 | 200 × 70 × 20 | 2.0 / 2.5 | 5.8 / 7.2 | 430 / 530 | 43.0 / 53.0 |
| C225 | 225 × 75 × 20 | 2.0 / 2.5 | 6.4 / 8.0 | 590 / 730 | 52.4 / 64.9 |
| C250 | 250 × 75 × 25 | 2.5 / 3.0 | 8.6 / 10.3 | 990 / 1 170 | 79.2 / 93.6 |
| C300 | 300 × 80 × 25 | 2.5 / 3.0 | 9.7 / 11.6 | 1 550 / 1 830 | 103 / 122 |
Nominal values for the section as rolled; effective section properties for design to EN 1993-1-3 are lower and are supplied with the calculation note. Other flange and lip sizes on request.
Span guide
| Section | 0.75 kN/m² total load | 1.0 kN/m² | 1.5 kN/m² |
|---|---|---|---|
| C150 × 2.0 | 5.5 m | 5.0 m | 4.2 m |
| C175 × 2.0 | 6.0 m | 5.5 m | 4.8 m |
| C200 × 2.0 | 6.5 m | 6.0 m | 5.2 m |
| C200 × 2.5 | 7.0 m | 6.5 m | 5.6 m |
| C250 × 2.5 | 8.0 m | 7.5 m | 6.5 m |
| C300 × 3.0 | 9.0 m | 8.5 m | 7.5 m |
Loads are total (dead + imposed/snow) on the roof slope; wind uplift, purlin spacing and sag-rod restraint change the result. For bays above 7.5 m or multi-span continuity, see Z purlins.
Lengths and stock
C purlins are made to order — every job has its own hole pattern — in 7–12 working days after drawing approval; standard lengths 3–13.5 m in 0.5 m steps, any length within that. Cleats, sag rods (Ø 10–16 mm threaded), bridging, eaves struts and anti-sag bars are supplied with the purlin package so the site gets one delivery.
Punching, fixing and installation
Holes are punched in-line before forming: 14 or 18 mm bolt holes at the ends to the cleat pattern, Ø 12–18 mm sag-rod holes at mid-span or third points, and slots or bracing holes as drawn. Purlins are fixed to rafter cleats with M12/M16 8.8 bolts — two per end for C sections — and the roof or wall sheeting is screwed through the top flange, which is what restrains the section against twist; sag rods at 1/2 or 1/3 span keep the purlins straight under sheeting load and during erection. Cutting on site is by cold saw or grinder with zinc-rich touch-up; do not flame-cut or weld galvanized purlins except with extraction and repair.
Where it is used
- Roof purlins on single-span portal frames and trusses (bays to ≈ 7.5 m)
- Wall girts and eaves beams
- Mezzanine floor joists and platform framing
- Door, window and louvre framing in cladding
- Back-to-back C sections as light beams and columns
- Solar-mount and agricultural building framing
C purlin vs Z purlin
A Z purlin can be lapped over the rafter to make a continuous beam, cutting weight 20–30 % on buildings of three bays or more, but its unequal flanges must be oriented correctly and it needs the sleeve or overlap detail. A C purlin is simpler, symmetric and cheaper per piece on short single spans, girts and framing. Both come from the same strip; the C & Z purlin overview compares systems, and for cladding battens and framing the lighter omega profile and M profile apply.
Price
C purlins are priced per ton (or per metre) on the section, thickness, quantity and punching pattern — the galvanized strip price is the base and forming, punching and length add per job — so we quote against the drawing rather than from a list band. Cleats and accessories are quoted per piece.
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
C purlin is bundled per size and length in strapped packs of 1–2 t with timber bearers and edge boards, nested (C in C, Z in Z, omega stacked) to save volume; each bundle tagged with section, thickness, length, count and heat. A 40' HC takes 20–24 t of nested 6–12 m purlins; up to 13.5 m by flat-rack or breakbulk from Derince. Customs heading 7216.61.
| Term | Detail |
|---|---|
| MOQ | 5 t per section size |
| Incoterms | FOB Istanbul · CIF / CFR Gulf, Africa · DAP EU, Balkans, Iraq, Caucasus · DAP Aktau |
| Lead time | 7–12 working days after drawing approval |
| Packing | Nested bundles 1–2 t, strapped, timber bearers, tagged |
| Container / truck | 40' HC ≈ 20–24 t nested; 13.5 m by flat-rack |
| Documents | Invoice, packing list, EN 10204 3.1 (strip), CE DoP (EN 1090-1), certificate of origin; SASO / SONCAP on request |
| Payment | 30% advance, balance against B/L copy; L/C at sight above 100 t |
Certificates
C purlin carries the EN 10204 3.1 certificate of the galvanized strip (grade, yield, zinc mass) and our roll-forming record (section dimensions, hole pattern check, length); CE marking under EN 1090-1 execution class 2 and a structural calculation note per span are supplied on request.
How to order
Send the purlin schedule or the building drawing: section (e.g. C200), thickness, grade (S280GD / S350GD), zinc (Z275), lengths and quantity per length, hole pattern (cleat, sag rod, bracing), accessories, and the delivery port; we return a quotation and a shop drawing for approval within two working days.
Standards
- EN 10346 — S280GD / S350GD + Z275 strip
- EN 1993-1-3 — design of cold-formed members
- EN 1090-1 / -2 — CE marking, execution class 2
- EN 10204 3.1
Grades
Grade data sheets (chemistry, mechanicals, equivalents) are on our reference site: S280GD · S350GD · S450GD
Frequently asked questions
What is a C purlin?
A cold-roll-formed lipped channel section in galvanized high-strength strip (100–300 mm deep, 1.5–3 mm thick) used as a roof purlin, wall girt or light framing member, bolted flat to cleats on the rafters.
What sizes of C purlin do you make?
C100 to C300 in 1.5, 2.0, 2.5 and 3.0 mm, lengths 3–13.5 m, from S280GD or S350GD Z275 strip, punched to drawing.
How far can a C200 purlin span?
As a guide, C200 × 2.0 spans about 6 m at 1.0 kN/m² total load and 1.5 m spacing; C200 × 2.5 about 6.5 m. Design to the actual loads with the calculation note we supply.
What is the weight of a C purlin per metre?
From 2.7 kg/m (C100 × 1.5) to 11.6 kg/m (C300 × 3.0) — see the section table.
C purlin or Z purlin — which should I use?
C for single spans, girts and framing up to about 7.5 m; Z for continuous multi-span roofs where lapping saves 20–30 % of steel.
Are C purlins galvanized?
Yes — rolled from pre-galvanized Z275 strip (275 g/m²), so the zinc is continuous and no post-treatment is needed; ZM coating on request.