As a major supplier of Polycarbonate Profiled sheeting to builders and roofing contractors, it is in our interest to ensure that the performance characteristics of this product are fully understood by both specifiers and contractors.
There is quite often some confusion as to the suitability of Polycarbonate sheeting for particular applications, and its general performance characteristics. The following information is provided to help you understand both its advantages and limitations, according to how and where it is used.
- Polycarbonate is available in lengths of up to 8.1 metres in corrugated profile and 6 metres for 5-Rib profile. We recommend using a maximum length of 6 metres, please read item 2.
- The 6 meter maximum length is well justified. Polycarbonate has a thermal co-efficient of 6.75 x 10-5 cm/cm °C, which equates to a linear expansion of up to 16.2mm over a 6 meter run.
- Profiles available in Polycarbonate sheeting are limited to Corrugated and Trimdek. There are no decking profiles.??Maximum allowable spans, wind pressure up to 1kPa are as follows:??Corrugated profile – nominal thickness 0.8mm, Span 0.9 meter.?Trimdek profile – nominal thickness 0.8mm, Span 1.0 meter.??As wind pressure increases, the spanning capacity drops dramatically. It should be noted that the above spans are based on consideration of bending strength only; failure at fixing points can be expected to occur at substantially lower loads.
- Polycarbonate is essentially a by product of the petro-chemical industry. In turn, Polycarbonate is therefore susceptible to chemical reaction, especially to petro-chemical based products.??It is important to note, that even neutral cure silicone should not be applied to Polycarbonate, as it weakens the sheet causing it to rip or fracture, sometimes within weeks of application. If sealant is necessary, use only Seal-Once a special silicone containing polycarbonate. Using incorrect sealant voids the warranty.
- While Polycarbonate has a very high impact strength when new, UV degradation substantially lowers this strength. Caution is always required to ensure that the UV protective coating is facing the sun in accordance with the product label or marking.
- Safety mesh is always required with Polycarbonate roofing. Polycarbonate is non-trafficable and does not meet the requirements of AS/NZS 1562-3 1996 : Resistance to impact (sandbag) for roofing sheet materials.
- The warranty on Polycarbonate may vary slightly between suppliers but it is essentially: Solasafe features a lifetime warranty. For full warranty details, please contact your nearest Zammit Roofing office.
It is Zammit Roofing’s experience that Polycarbonate has a number of limitations when used in Industrial/Commercial installations. The thermal co-efficient being a significant factor, also the relatively small spanning capacity, limited choice of profiles and general UV degradation. Clear Polycarbonate has unmatched light transmission properties, but this also means very high heat transmission which in many applications is unacceptable.
We have found that when Polycarbonate sheeting is specified, it is usually because the specifier is seeking to select a product, which hopefully, will outperform the industrial grades of fibreglass roofing generally available.
However, Zammit Roofing have made a significant advance with the introduction of “Wonderglas GC” gel coated premium grade industrial sheeting that has a 25 year warranty. The gel coating and base sheet are at the cutting edge of resin technology. UV resistance is so high, that loss of light transmission after 10 years is just 10%, with only minimal change in later years.
“Wonderglas GC” outperforms and outlasts other plastic roofing materials and is compatible in all respects to metal roofing.
Another option if you did require Polycarbonate would be to use Twinwall, which has many advantages over standard Polycarbonate.