October 2020

or less noble) would have resulted in rapid
galvanic corrosion of the latter, and as a result
the roof had to be altered in the design phase to
negate the bi-metallic corrosion issues that would
have been created.
Working with the design team during the
specification stage we were able to address the
issue. This involved changing the roofing material
to keep the external elevation materials as that
specified by the architects, with our Proteus HR
rainscreen system and a TECU Classic external
veneer.
Interestingly, these two metals – zinc and copper
– on their own are some of the most durable and
long-lasting roofing and cladding materials
around. But put them together, or any other
metals not closely positioned on the Galvanic
Series, and rapid corrosion will be the result.
There are various ways of avoiding galvanic
corrosion and the main ones are:
• Selecting metals with similar corrosion
properties.
• Separating the two materials with an inert
spacer.
• Breaking the electrical connection by insulating
the two metals from each other.
• Applying coatings to one or both materials.
• Adding corrosion inhibitor.
It’s worth remembering that bimetallic corrosion is
not just limited to roofing and façade elements.
Anywhere in a building where two or more metallic
elements are used in close proximity – they do not
need to be touching – can result in galvanic
corrosion. That includes air conditioning pipework,
hot and cold water systems and structural framing
connections, amongst others. With such a wide
variety of potential trouble spots, it is not possible
to avoid unfavourable dissimilar metal
combinations, and so the best solution is to work
with your supply partner to design it out.
Most designers understand that the presence of
different metals in any element of a building can
result in localised corrosion. A supplier that goes
to them with a solution to avoid it is always going
to create a favourable impression with an
architect or main contractor. All metals react with
their environment, although some are more
reactive than others. Knowing this and factoring it
in at design stage can avoid issues after the
project is handed over.
Contact Proteus Facades
0151 545 5075
www.proteusfacades.com
Solvent-free and
non-flammable, Seal It Liqui d Membrane is designed
for profession nal roofing applications as the ultimate alternative to
bitumen based and GRP roofing membranes: ideal for all existing roof
substrates. With outstanding water resistance and weather proofing it is
self-levelling, gap-bridging, non-shrinkin g and non-cracking.
Yo ou can even apply it when it’s wet!
Full available system comprises: Primer, Rein forcing Mat, Sealer and
Accelerator. Av vailable in either white or gr rey and in stock now.
25
YEARS
GUA
RANTEED
U nit G16, River B ank Way, Lowfields Business Park, Elland
, West Yorkshire HX5 9DN
Tel: +44(0)1422 315300, Fax: +44(0)142 22 315310
Email:
sales@bond-it.co.uk Website: www.bond-it.co.uk
OCTOBER 2020 TC 51