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, greca and 5 rib profiles.
The following table shows details
An 8.1 metre maximum length is
well justified. This is because polycarbonate has a thermal co-efficient of 6.75 x 10-5
cm/cm °C, which equates to a linear expansion of up to 21.8mm over a8.1
metres (based on an overall 40° temperature variation).
Profiles available in
Polycarbonate sheeting are limited to Corrugated Greca and 5 Rib. There are no
Maximum allowable spans, wind pressure up to 1kPa:
Corrugated & Greca profiles - nominal thickness 0.8mm, Span 0.9 meter.
5 Rib profile - nominal thickness 0.8mm, Span 1.0 meter.
As wind pressure increases, the spanning capacity drops dramatically. It
should also 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
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 sealing is necessary,
use only a silicone sealant specifically made to be compatible with
polycarbonate. Use of
incorrect sealants voids the warranty.
While Polycarbonate has a
very high impact strength when new, weathering 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 in installations over 3.0 metres in height. Polycarbonate is non-trafficable and does not
meet the requirements of AS/NZS 1562.3 : 2006 : Resistance to impact (sandbag)
for roofing sheet materials.
The warranty on Polycarbonate
may vary slightly between suppliers but it is essentially (as given by
5 years against hail fracture, (usually limited to hailstones up to
19mm in diameter in winds up to 75km/hr). Solasafe
features a lifetime warranty. For full warranty details, please contact your
nearest Ampelite office.
10 years against excessive yellowing of clear sheets.
(c) 10 years against loss of light transmission exceeding 10%
NOTE: Lifetime Warranties offered are
always for domestic applications only.
It is Ampelite'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, Ampelite 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.
outperforms and outlasts other plastic roofing materials and is compatible in
all respects to metal roofing. This is
important especially considering spanning vs. wind pressure on larger projects.
All current sheet / decking profiles and most superseded profiles are available
in required lengths.
Should you wish to
discuss any of the above, view early and current installations of both polycarbonate and
"Wonderglas GC", or would like further technical information, please contact
the Ampelite branch office in your state.