Most polycarbonate problems — leaks, yellowing or cracking — are caused by incorrect installation, not by the material. Follow these rules and your sheets will deliver the lifetime they were designed for.
1. UV side faces the sun
The UV-protective layer is on one face only — the face with the printed protective film. Install the sheet upside down and the protection will not work, and the sheet will yellow quickly.
2. Remove the protective film right after installation
Keep it on while cutting and fixing to prevent scratches, but remove it as soon as you finish. Left in the sun for long, it bonds to the sheet and becomes hard to peel.
3. Flutes run in the direction of the slope
With multiwall sheets, keep the flutes vertical along the roof slope so any condensation inside can run down and drain out.
4. Give it enough slope
Never install sheets completely flat. A slope lets rainwater run off and helps the surface clean itself.
5. Allow for thermal expansion
Polycarbonate expands with heat. Leave a small gap at the edges, drill fixing holes slightly larger than the screw, and do not over-tighten.
6. Seal multiwall edges
Use aluminium tape on the top edge and breather (anti-dust) tape on the bottom edge so dust and insects stay out of the flutes while moisture can escape.
7. Use suitable fasteners and washers
Use screws with EPDM rubber washers that seal the hole without crushing the sheet. Avoid sealants and silicones that are not specified for polycarbonate, as they can damage the material.
8. Clean the right way
Clean with lukewarm water, mild soap and a soft cloth. Avoid alcohol, solvents and abrasive brushes.
