Clearview National December 2014 - Issue 157 | Page 63

GLASS&SEALEDUNITS

A Strong
Warning
for IGU’s
New guidance has been published by
the British Woodworking Federation
(BWF) to help firms placing orders for
insulating glazing units (IGUs) including
narrow cavity or ‘slim’ glass units.
»»Such units – highly
energy efficient, hermetically
sealed units designed to keep
homes warmer in the winter and
cooler in the summer – usually
consist of two or more panes
of glass separated by a spacer
material and sealed together at
the edge. The space between the
panes is filled with air or an inert
gas such as argon or krypton
which, together with a lowemissivity glass coating, produces
the unit’s excellent insulating
properties.
‘Slim’ units have cavities of
8mm or less and often have a
reduced edge seal and they are
favoured in listed buildings or
conservation areas as they allow
thinner timber profiles and bead
detail.
However, concerns have been
raised by BWF members about
the quality of some of these
units supplied by a range of
different manufacturers. Further
investigation by the BWF has also
highlighted that there are some
‘slim’ IGU suppliers who are
seemingly unable to provide the
appropriate test evidence required
to ensure performance of the unit
in the long term.
Kevin Underwood, BWF
Technical Director, says:
“We have received a number
of queries through the BWF
technical helpline and in our
technical committee and council

meetings particularly concerning
certain ‘slim’ insulating glass units
on the market. The new guidance
addresses this concern, helping
buyers to exercise appropriate care
and ensure that when purchasing
IGUs they know what to ask
for and what they should expect
from supporting documentation
from their suppliers. IGUs that
have been suitably tested and
manufactured in a controlled
manner should provide the levels
of performance our members are
looking for.”

‘IGUs that have
been suitably tested
and manufactured
in a controlled
manner should
provide the levels
of performance
our memebrs
are looking for’
Kevin Underwood points out
that CE marking for glass units
became mandatory on 1 July
2013, so this should help buyers
of all types IGU that are covered
by the harmonised standard BS
EN 1279-5.
The BWF is advising its
members to seek confirmation
from suppliers that all the IGUs,

Wishing you a merry
Christmas and a
prosperous New Year

both ‘standard’ and ‘slim’ types
will be CE marked and will meet
the requirements for the durability
of glass units given in the BS EN
1279 series of standards.
Kevin Underwood explains that
buyers should insist that units
should only be supplied when
there is the correct and full test
evidence to accompany them:
“In order to establish that the
test evidence applies to the glass
units which you’re intending
to buy, you should ask the
supplier for a copy of the system
description, and check that this
is fully consistent with what
you’re buying,” explains Kevin
Underwood.
“The IGUs should also have
been tested for durability, which
means meeting the requirements
for moisture penetration, gas

leakage if appropriate, and edge
seal strength. The production
of the IGUs should also follow
a Factory Production Control
system and periodic testing
meeting the requirements of BS
EN 1279.”
Members are also advised to
discuss the length of warranty
that is being offered by their
glazing suppliers on these units
and to check the detail as to what
these warranties will cover. They
should also confirm that they
will employ an acceptable glazing
method using appropriate and
compatible materials in an effort
to avoid future problems.
A copy of the BWF fact sheet on
Slim IGUs can be downloaded
at: http://www.bwf.org.uk/
assets/bwf-igu-advice.pdf

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