Choosing the right Modek Polycarbonate Roof Sheet

MODEK’s polycarbonate products can be selected along a range of criteria, depending on the requirements of the application in question:

• Colour and clarity
• Sheet form
• Thickness

Colour and clarity

More than 70% of the heating effect of the sun is carried between 350 and 800 nanometres (generally, the visible light spectrum). More than 85% of these wavelengths are transmitted through a clear polycarbonate sheet. It is possible to vary levels of light transmission, and therefore the amount of heat that is transmitted, by changing the colour of the polycarbonate sheeting or by choosing a more opaque, diffusing sheet.

It is commonly available in clear and tinted options, with clear and most tints providing direct light, while clear patterned and opal tint provides diffused light and gives a soft quality to the light. The standard colours available are clear, white (opal 50) and bronze. Silver (Heat Stop), blue and green are also available subject to order quantity.

Sheet form

Polycarbonate (PC) comes in three sheet forms, each with its own particular characteristics and properties:
• Solid (flat or domed)
• Profiled
• Multi-wall

Solid (flat or domed)

Solid polycarbonate offers good optical clarity and superb workability. It can be cold-curved on site, is suitable for use with a variety of glazing bar systems, and can be moulded into various shapes such as domes and pyramids.

Profiled

Profiled polycarbonate matches profiled roof cladding and allows the sky to be viewed through a corrugated material, a feature popular with many designers. MODEK polycarbonate comes in all the profile shapes generally used for non-translucent roofing and cladding in South Africa.

That said, extrusion and vacuum-forming techniques allow a huge variety of profiles to be produced. As a result MODEK can manufacture new or additional roofing profiles, although it should be noted that the time and cost incurred is likely to be considerable.

Multi-wall

Multi-wall polycarbonate is an insulating glazing material. Thicker sheets with more walls achieve the highest thermal performance, typically 1.6W/m2K (watts per square metre per kelvin) for a 25mm five-wall sheet.
Structured polycarbonate is most commonly used in most domestic and many commercial conservatories. Like solid polycarbonate it can be cold-curved on site (although to a much lesser degree), it can be used in a variety of glazing bar systems, and has a very high strength-to-weight ratio. making it ideal for the creation of glazing features.

Nominal thickness

Because of the inherent variances of tolerance experienced when profiling a thermoplastic extrusion, the actual thickness of a sheet varies slightly from one point to another. As a result, the internationally accepted unit of measurement for polycarbonate sheeting is the nominal thickness of the sheet, established by representative measurements (taken be vernier or micrometer) at various points across the full width of the sheet.

MODEK manufactures two nominal thickness specifications:

• 1.00mm nominal thickness
• 1.25mm nominal thickness

A layer of UV protection PC is co-extruded on the weathering side of all MODEK polycarbonate roof sheets.

1.00 mm nominal thickness

1.00 mm nominal thickness is manufactured as a lightweight polycarbonate sheet to be used mainly in lighter, domestic applications and applications where exposure to wind is minimal and spanning requirements are less than normal. The 1.00mm nominal thickness products are restricted to certain profiles only.

1.25 mm nominal thickness

1.25 mm nominal thickness is the standard weight specification for all industrial installations. This specification will meet the rigorous conditions found in an industrial environment, particularly that of deflection under load (positive and negative), handling on-site, spanning capabilities and general robustness of profile.