Multi-span greenhouses are built from pre-galvanized tube: arches in 25×50 to 32×62 rectangular or Ø25–32 mm round (wall 1.2–1.5 mm), columns 50×50–80×80 (wall 1.5–2.0 mm), and gutters roll-formed from Z275 coil (1.5–2.0 mm). Pre-galvanized strip is the standard finish; hot-dip for coastal sites. Cut-to-length, MOQ 5 t.
A greenhouse is a steel frame wearing plastic film — and the frame decides whether the house survives ten seasons or three. Commercial growers order tube by the container with exact cut lengths per arch position. Here is the sizing and coating map we run for greenhouse projects from Vietnam to Morocco.
Tube Sizes by Structure Position
| Position | Typical Section | Wall | Notes |
|---|---|---|---|
| Arches | 25×50 / 27×54 / 32×62 rect, or Ø25–32 mm round | 1.2–1.5 mm | Spans 8–9.6 m per bay; double-span arches |
| Columns | 50×50 / 60×60 / 80×80 square | 1.5–2.0 mm | Carry gutter and arch loads |
| Gutters | Roll-formed from 1.5–2.0 mm Z275 coil | — | Drainage between spans; supply as slit coil or formed |
| Braces & purlins | 25×25 / 30×30 square | 1.2 mm | Arch stability, film locking profiles |
| Doors & vents | 20×20 / 25×25 square | 1.2 mm | Kit parts, drilled |
The Coating Question: Pre-Galv vs Hot-Dip
- Pre-galvanized strip (standard): the tube is formed from already-galvanized coil — uniform Z60–Z275 finish, cheapest, perfect for film greenhouses in moderate climates. Humidity inside a greenhouse is exactly what zinc handles well.
- Hot-dip after fabrication: +25–40% cost, but weld zones and cut edges get full protection — for coastal greenhouses, nurseries with fertilizer exposure, and glass houses where the frame is permanent infrastructure.
- Warning: bare (black) tube inside a humid greenhouse rusts within one to two seasons — this is the wrong place to save on coating: full comparison →
Container Planning for a Greenhouse Project
- A 1-hectare multi-span house (10 bays × 40 m) runs roughly 30–40 t of tube and gutters depending on snow/wind load.
- Cut-to-length per position (arches in one length, columns in another) — the kit sorts directly into bundles by section: cutting service →
- 2 × 40GP containers typical; arch bundles nested to protect the zinc layer during transit.
- Film, fixings and insect nets sourced locally — we supply the steel frame package.
Related sizes: square/rectangular tube table → · pipe & tube product page →
Greenhouse project? Send the tube list.
Sections, cut lengths and coating choice to [email protected] or WhatsApp +86 191 5745 8011 — container plan and FOB/CIF quotation in one working day. MOQ 5 t.
Request Greenhouse Tube Quote