Twinwall polycarbonate suits greenhouses and lightweight covers, triplewall is ideal for carports and lean-tos, while thicker multiwall sheets are the standard choice for conservatory roofs where insulation matters. The right sheet depends on your span, insulation requirements and the load your structure needs to carry.
What is multiwall polycarbonate?
Multiwall is the umbrella term for polycarbonate sheets with internal cellular structures. Twinwall has two walls, triplewall has three, while thicker multiwall sheets contain more complex internal chambers. More walls generally mean greater strength and improved thermal insulation.
Which polycarbonate sheet thickness do you need?
| Thickness | Structure | Best suited to |
| 4mm to 6mm | Twinwall | Cold frames and greenhouses |
| 10mm | Twinwall | Canopies, pergolas and lighter roofing |
| 16mm | Triplewall | Carports, lean-tos and larger covers |
| 25mm | Multiwall | Conservatory roofs |
| 35mm | Multiwall | Conservatory roofs where improved insulation is needed |
For larger or more complex roofs, support spacing and the specific glazing system must also be considered.
What thickness of polycarbonate do I need for a conservatory roof?
25mm or 35mm multiwall polycarbonate is generally the best choice for a conservatory roof. The thicker construction creates more internal air chambers, helping improve thermal performance. Choose between them based on the roof design, rafter spacing and the level of insulation required.
What thickness of polycarbonate is best for a greenhouse?
4mm to 6mm twinwall polycarbonate is usually sufficient. Thicker is not automatically better. Greenhouses need good light transmission as well as protection, so choosing a sheet designed for the application is more important than simply choosing the thickest option.
What thickness is best for a carport or canopy?
10mm twinwall or 16mm triplewall polycarbonate are the usual choices. The correct option depends on the span, support structure and local wind or snow loading.
Does thicker polycarbonate insulate better?
Yes. Thicker sheets generally contain more air chambers, which improves insulation. However, they also cost more and can reduce light transmission slightly. The practical rule is simple: choose the thickness your project needs, not automatically the thickest available.
Which polycarbonate tint should you choose?
Clear maximises light, opal helps diffuse light and reduce glare, while bronze provides a darker finish and can help reduce glare and solar gain.
What else do you need alongside the sheets?
You may also need glazing bars, end caps, breather tape, anti dust tape, fixing buttons and suitable sealants. PlastixPlus supplies the accessories needed to complete a polycarbonate roofing system.
Need help choosing? PlastixPlus can supply polycarbonate sheets, with delivery or collection available from the Reading trade centre. Call 0118 939 4503 for a quote, quantity take off or product advice.
