June 2020

understandably very risk averse, mentions A1
rated cladding to the architect, who takes this
literally (not even considering the A2 option) and
so this specification echoes right down the line to
the contractor and installer.
“We have recently seen all sorts of acrobatics
and contortions undertaken in an effort to
achieve an A1 Euroclass rating for coated
aluminium cladding”
Unintended consequences
This is where real issues occur and unforeseen
challenges are created. Imagine a contactor
faced with a client who has (perhaps speciously)
specified an A1 rated aluminium cladding
system. Then they see that the spec includes a
high gloss colour, which due to professional
indemnity cover needs to last at least 25 years.
This is where the contractor finds themselves
between a rock and a hard place.
Of course, uncoated aluminium achieves a clear
A1 rating without a problem, but as soon as it’s
coated, it loses its revered A1 rating and
becomes A2. It’s still highly functional, legal at
18 or 11 metres and wholly appropriate for the
project, but it’s not what the customer wanted.
Hence, we have recently seen all sorts of
acrobatics and contortions undertaken in an
effort to achieve an A1 Euroclass rating for
coated aluminium cladding.
Taking the coating from the recommended minimum
of 60µ to 20µ is one trick we’ve seen. This enables
the cladding to score a zero on the smoke test,
pushing it from an A2 to an A1 rating. This
approach, however, leads to problems of quality
further down the line. Firstly, the coating simply will
not perform in the way it was designed to. The
colour and gloss will be dull and even inconsistent.
Furthermore, within a few years wear and tear will
take its toll, creating a shoddy exterior – certainly
not lasting the 25 years as required!
Another way we’ve seen some suppliers achieve
A1 rating on PPC cladding is to test it via a
specific category within EN13501 reserved solely
for ‘non-substantial parts’. Combining other
standards such as EN11925 and ISO 1716
calorific value test, this route essentially omits
the EN 1182 combustibility test – enabling it to
gain the A1 rating.
While this approach may be within the letter of
the law, we are not convinced it is the best way
for an industry to maintain trust. The desire for
A1 PPC (when A2 rated cladding is perfectly safe)
may be driven by insurers’ attitudes to perceived
risk, but this well-intentioned objective is placing
unrealistic pressure on some parts of the
cladding sector.
What’s the solution?
In our experience, for most high rise projects a
tried and tested PPC solution is by far the
preferred option. While achieving EU class A2 fire
rating, more than adequate in terms of its flame
retardation performance, this route provides
numerous benefits over alterative solutions.
Indeed, results from the Interpon D fire test report
for the performance of aluminium which has been
powder coated, met all criteria for Class 0
building regulation approval.
The PPC route provides a huge range of durable
colours and finishes, which actually extends the
life of the aluminium. As customers only pay for
the coating that is used on specific sheeting, this
option is also a lot cheaper than going for the ‘off
the shelf’ PVdF alternative which creates much
more waste material. Coating post fabrication
also allows contractors to achieve uniformity
across the full project – producing gutterings and
architectural flanges in the same colour without
significant added coat or the hassles of minimum
order sizes.
When considering solid aluminium rainscreen
systems, it’s important to opt for an accredited
PPC coating, which is developed in conjunction
with a proven applicator. We work with Prism
Powder Coating for this process as they use only
external grade architectural powders to create a
completely environmentally-friendly powder
coated finish which has both Qualicot and
Interpon D approved status. Even better, the
process is chrome-free which adds to the
sustainability of the project.
Granted, the colour and finish range offered by
PVdF is impressive, providing architects with an
almost endless array of options including
metallic, chromatic and wood grain. However,
there are important limitations to bear in mind
when specifying pre-coated aluminium such as
the potential for tooling damage during
manufacture, longer lead times and cost per m2,
which can be considerably more expensive when
compared to PPC.
The Grenfell tragedy has rightly pushed safety to the
top of the agenda. While this focus on a material’s
ability to suppress fire, smoke and fumes is a
welcomed step, this also requires an improved level
of technical understanding among specifiers and
contractors alike. Too often, we’re seeing overengineered
solutions that are needlessly adding
cost, complexity and even compromising the
aesthetic and longevity of cladding systems.
More training is certainly needed to bring the
industry up to speed with regards to the
Euroclass regime and other relevant safety
standards. This, along with better, early dialogue
across the supply chain on cladding specification
will help to eradicate this troubling trend.
Contact MSP Scotland
01236 729591
www.mspcladding.co.uk
JUNE 2020 TC 43