Storage & sheet preparation
- Store sheets on a flat surface. Use an opaque cover, tightly secured, to protect from wind, rain and sun. Storage is always preferable indoors.
- Ensure that the clearly marked UV protected surface of the Multiwall sheet is to the outside.
- Multiwall sheets must always be installed with the ribs running vertically, or up-slope.
- Roofs should always be designed with a minimum slope of 5° to allow adequate rainwater run-off.
- Multiwall sheet can be cut with a fine tooth circular saw or hand saw at a shallow angle.
- Use aluminium sealing tape at the top of the sheet to prevent ingress of moisture, dust and insects.
- Use breather tape at the bottom end of the sheet to minimise condensation and prevent dust or insects entering the sheet.
Thermal movement & fixing
Important – polycarbonate sheet will expand in the heat and contract in the cold.
- When drilling fixing holes they must be oversized (18mm) to allow the sheet to move.
- Drill between ribs and at least 40mm from the edge of the sheet.
- Fixings must not be overtightened, again this allows the natural movement of the sheet and will avoid unnecessary damage to the sheet.
Finishing
- Cover breather tape with a ‘U’ profile sealed to the top face of the sheet with a small silicone bead.
- Use a low-modulus neutral silicone as an all-purpose silicone will cause polycarbonates to crack and disintegrate.
- Ensure all film is completely removed immediately after installation.
When installing any roofing material, including rooflights, ensure that safe working methods are adopted and appropriate safety equipment is used.