A polycarbonate multiwall sheet is a translucent plastic panel with a hollow, ribbed structure. Between the outer and inner walls run longitudinal channels (hollow cells), separated by thin webs. This construction makes the sheet light, strong, and insulating. The panels are also called hollow-chamber or twin-wall/triple-wall polycarbonate sheets.
Properties
- Lightweight — much lighter than glass for the same area, so a lighter supporting structure will suffice
- Impact-resistant — polycarbonate is very strong and does not break easily; it is also used in bullet-resistant glazing
- Insulating — the hollow channels trap air, which improves thermal insulation. The more walls (2, 3, or more layers), the higher the insulation value
- Translucent — the panels transmit daylight, from near-clear to opal (milky)
- UV protection — the outer face usually has a UV-resistant coating against yellowing
Application
Polycarbonate multiwall sheets are widely used for:
- Veranda and patio canopies
- Carport roofs and porch roofs
- Greenhouses
- Rooflights and skylights in industrial halls
Points to note
- Install the sheets with the channels running vertically or sloping, so condensation can drain out
- Seal the ends with special vented tape and profiles to keep dirt and moisture out of the channels
- Allow for thermal expansion: polycarbonate expands in the heat, so screw holes are drilled oversized
Related terms
- Polycarbonate
- Plastic
- Light transmission
- Porch roof
- Rooflight
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