Roofs should always be designed with a minimum slope of 5° to allow adequate rainwater run-off.
Ensure that the UV protected surface (marked on protective film) of the Polycarbonate sheet is to the outside. 50mm of protective film should be peeled back from the edges of the sheet before installation and the residual film removed after installation is complete. If the project is likely to take time to complete, regularly check that the film does not bond on to the sheet, particularly in sunny weather.
Always ensure that sealants, gaskets and other materials used with Polycarbonate do not have a detrimental effect on the material. Low-modulus neutral silicone MUST be used with Polycarbonate sheet.
A sealing (blanking) tape is applied at the top of the sheet to prevent ingress of moisture, dust and insects. A breather tape applied to the bottom end of the sheet allows air to move freely in and out of the sheet, helping minimise condensation by equalisation of the air vapour pressure inside and outside the sheet. The breather tape also prevents dust or insects entering the sheet. The breather tape must be covered with a ‘U’ profile, sealed to the top face of the sheet with a silicone bead to protect both the tape and the lower end of the sheet from rainwater run-off.
Polycarbonate sheets should be installed with its ribs running in the direction of the slope.
To ensure optimum security under load it is important that at least one vertical rib of the sheet is securely clamped in the glazing system.
Polycarbonate can be cut with a fine tooth circular saw or a hand saw held at a shallow angle. Dust should then be removed from the sheet using a vacuum cleaner or dry compressed air. It is necessary to support the sheet close to the cut and to hold it firmly to prevent stress and vibration. Sheets must not be fixed or clamped too tightly as this will prevent thermal expansion and contraction and will adversely affect the installation.
At the eaves purlin additional fixing is necessary to prevent wind uplift and downslope slippage due to repeated thermal movement. One button per sheet width, centrally located between glazing bars should be sufficient.
The sheet must be supported firmly underneath when drilling. Holes should not be drilled any less than 40mm from the edges of the sheet.