Multiwall Polycarbonate Sheet

Twin-wall, triple-wall and honeycomb structures — lighter and warmer than solid sheet, for roofing and greenhouses.

Multiwall polycarbonate — hollow sheet, twin-wall, or in Chinese usage 阳光板 — carries internal ribs that trap air between two or more skins. The trapped air does two useful things: it insulates, and it lets the sheet span further for its weight.

A 6 mm twin-wall sheet weighs about 1.3 kg/m². The same area in 6 mm solid sheet weighs over 7 kg. On a greenhouse roof that difference decides the entire frame specification.

Twin-wall multiwall polycarbonate sheet showing internal rib structure

Specification

Property	Specification
Structures	Twin-wall, triple-wall, X-structure, honeycomb
Thickness	4 mm – 20 mm
Widths	1220 mm and 2100 mm standard
Length	Cut to order; commonly 5.8 m or 11.8 m for container loading
Weight (6 mm twin-wall)	Approx. 1.3 kg/m²
Light transmission	78–82% clear; opal and bronze options available
UV protection	Co-extruded on the exposed face as standard
Colours	Clear, opal, bronze, blue, green

Choosing a structure

Twin-wall (4–10 mm) — the default for carports, walkways and small greenhouses. Cheapest per square metre and easiest to handle.
Triple-wall and X-structure (8–16 mm) — better insulation and longer spans. Worth the cost where heating bills or snow loads matter.
Honeycomb (10–20 mm) — the stiffest construction for its weight, used where the span is long and the frame is minimal.

Installation points that cause failures

Three mistakes account for most multiwall complaints, and none of them are sheet defects:

Ribs installed horizontally. The channels must run down the slope so condensation drains out. Horizontal ribs trap water, and the panel greens up within a season.

Ends left open or fully sealed. The top edge takes solid tape, the bottom edge takes vented tape. Sealing both ends traps moisture inside the flutes.

UV face installed downwards. The protected face is marked on the film. Fitted upside down, the sheet yellows in two to three years and the warranty is void.

Typical applications

Agricultural and horticultural greenhouses
Carport and vehicle canopy roofing
Walkway and platform covers
Industrial roof lights and daylighting strips
Swimming pool enclosures

Minimum order and lead time

This grade ships from 100 m² or 1 tonne — a trial pallet, not a full container. Standard sizes and stock colours run in 7–10 days; non-standard thickness or width in 12–18 days; add 3–7 days for CNC cut-to-size work. Quoted in USD on FOB, CIF or DDP terms. Full detail on the MOQ, lead time & shipping page.

Questions buyers ask

What span can multiwall polycarbonate cover?

It depends on thickness, structure, purlin spacing and local snow and wind loading. As a rough guide, 6 mm twin-wall suits purlins at 700 mm; 16 mm triple-wall reaches beyond 1500 mm. Send the frame drawing and load requirement and we will confirm.

Which side faces the sun?

The face carrying the printed protective film with the UV marking. Fitting it downwards removes the UV protection from where it is needed and the sheet yellows quickly.

Can multiwall sheet be curved?

Yes, cold-curved along the rib direction only, to a minimum radius of about 175× the sheet thickness. It cannot be curved across the ribs.

Request a quote MOQ & shipping

From the factory