FASTENING & ADHESIVES | MECHANICAL FASTENERS
WHAT SHOULD BE
CONSIDERED DURING THE
SPECIFICATION STAGE?
In order to ensure the fastener
and fastening system specified meet
the durability, weathertightness,
airtightness, aesthetic and structural
performance requirements of the final
product, specifiers need to consider
five key areas: whole lifecycle costs,
external and internal environment,
colour-matching needs, legislation
and regulation, and warranties.
THE IMPORTANCE OF
WHOLE LIFECYCLE COSTS
According to Kirwan, specifiers
should look at the whole lifecycle
costs of the fastener, not just the initial
costs: “Choose an A4 316 stainlesssteel
fastener and you are guaranteed
to meet the minimum requirements,
but if you buy cheap, they won’t last
as long and will need to be replaced
earlier than expected. This brings
about servicing, maintenance
and additional capital costs that
can be avoided by specifying the
appropriate fasteners first time
around.”
ONE SIZE DOES NOT
ALWAYS FIT ALL
Kirwan continues: “Buildings are
naturally exposed to the elements,
which differ dependent on where
the building is located. The external
environment of a building can
impact the effectiveness of fasteners
used. For example, when specifying
fastening systems for use on
buildings within 10km of the coast or
an estuary, there is a high salt content
in the air that can corrode fasteners.
Fasteners in these cases should be
made from A4 316 grade stainlesssteel.”
However, it isn’t just the external
environment of a building that
impacts on what fasteners should
be specified – the building’s use
can have implications. Swimming
pools, for example, cause a high
level of chlorine in the air, leading to
stress cracking within the fastening
material due to the corrosion process
as humidity and chlorine react with
the metal. These buildings would
be better suited using R5 or 1.4547
stainless-steel fasteners which are
less likely to be affected by chlorine
in the air.
COLOUR MATCHING
During the 1970s, the market share
for colour-coated cladding materials
dramatically increased, principally
within the industrial and retail
building sectors. Today colour-coated
cladding represents over 90% of
their total market, now widely used
as part of the cladding envelope on
many other building types such as
educational, healthcare, residential,
leisure and transport-related
buildings.
One key consideration for
specification is using powder coating
instead of the traditionally used
moulded headed fasteners for colour
matching. Moulded headed fasteners
are prone to UV degradation, whereas
powder coating offers toughness and
durability, as well as providing an
accurate match to the colour of the
surrounding weather sheet. Powder
coating is only very slightly affected
by UV light, so fading or weathering
is uncommon. The fastener head
remains small and compact and there
is no bulky plastic to cause visual
intrusion.
LEGISLATION AND
REGULATION
“Specifiers also need to consider
changing legislations and their impact
on fastening systems,” Kirwan says.
“For example, Part L2 of the Building
Regulations for England and Wales,
introduced in 2002 to help address
energy efficiency requirements in
non-domestic buildings, cast a light
on the importance of airtightness.
“A prime focus for the new
regulations is providing building
managers, landlords and tenants with
detailed and accurate information
about energy usage in their buildings
to enable them to identify areas where
energy is being wasted and where
there are opportunities for reducing
energy consumption.
“Effective seals are critical
in ensuring the airtightness of a
building. High grade butyl strip
weather and air sealants perform 20%
better than standard butyl sealant.
This type of sealant is manufactured
from cross linked butyl and is
therefore suitable for all corrosivity
categories C1-C5.”
WARRANTIES AND
CERTIFICATION
In wider, product design terms, it
is critical specifiers consider the
implication of the fasteners used on
the warranty of fastening systems.
It is expected that the fasteners are
warranted with the fastening system
that is being used, but often, they
are warranted separately. This can
mean that the whole system is not
warranted, causing complications
down the line.
Whilst fasteners are used in
abundance, these everyday heroes
are critical to overall quality.
Specifiers should consider fastening
solutions once they have an aesthetic
vision in mind to ensure the correct
fixing solution is used to achieve that
vision, as well as deliver whole life
costs and value. !
28 WWW.EUREKAMAGAZINE.CO.UK | FEBRUARY 2020
/WWW.EUREKAMAGAZINE.CO.UK