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.

As a condition of ensuring that Multiwall sheets perform at optimum throughout their service life and retain light transmission properties, it is recommended that the sheets be cleaned periodically using suitable household cleaning agents as follows:

• Use lukewarm water to rinse the sheet and soften dirt.
• Make up a solution of lukewarm water and ordinary household cleaner or a mild soap and use this to wash the sheet.
• A sponge or soft cloth should then be used to gently remove dirt and grime.
• The cleaning process should then be repeated and the sheet rinsed and dried with a soft cloth.
  

WARNING

Care should be taken to observe the following precautions:

1. Do not scrub  Multiwall sheeting with brushes or sharp instruments as the sheet will mark easily.
2. Never steam clean, use low pressures for pressure washing.
3. Avoid any abrasives or cleaners of a highly alkaline composition.
4. It is generally advisable in all instances to test any cleaner on a sample piece of the Obsidian roof sheet first and it should also be remembered that cleaners and solvents which state that they are suitable for cleaning polycarbonate may not be safe for use on the UV protective surface of the panels.