Insulate Magazine Issue 14 - January 2018

The only independent insulation industry trade magazine
Keeping Everything Moving
Supply and Demand
No Room for the Future
Specifications, for cavity wall constructions in particular,
have been carefully engineered around the contribution
a thermally efficient block on the inner leaf makes. That
leaves only a narrow window for an alternative product to
help achieve the same, which simply isn’t realistic given
the shortages experienced.
The implications of bringing a site to a halt are potentially
severe: extra costs, setbacks to the schedule, and the
possibility of losing a workforce if they move to another
site. The restless beast, therefore, demands an answer -
and it is usually demanded sooner rather than later.
Unfortunately, the specifications are so carefully
engineered that there is no contingency in the design
for product substitution. There’s often a limited
understanding of the likely implications of using something
different, and what on paper looks like a small change is
magnified and exaggerated when it comes to making it
work in reality.
For example, changing a lightweight block to a medium
density block might only worsen the U-value of the whole
wall by 0.01 W/m2K - let’s say, from 0.21 W/m2K to 0.22
W/m2K. Not the end of the world, it might seem - but
increasing the cavity insulation thickness by 5mm to claw
back that difference is easier said than done. Does the
insulation manufacturer make their product 5mm thicker
as a stock item?
Is there tolerance in the design to accommodate it if they
do? If there isn’t and they don’t then there certainly won’t
be the tolerance for a product 10mm or 25mm thicker.
How likely or practical is it that the design can be altered
to include a wider cavity, a wider inner leaf block, or a
layer of internal insulation?
Insulation Upheaval
Over the last twelve months it hasn’t just been the supply
of lightweight blocks that has exerted pressure - supply
issues in the insulation industry have caused their own
challenges.
The limited availability of rigid polyisocyanurate (PIR) foam
boards due to a shortage of one of the chemicals usedin
production has left contractors and installers looking for
alternatives. Which is fine … up until the point that products
are offered for the wrong reasons or applications.
And cavity walls remain one of the biggest areas of concern.
Approved Document C of the building regulations in
England and Wales advises that rigid insulating materials
for cavity walls should possess current certification, and
the products be installed in accordance with the contents
of that certificate.
(With the levels of exposure experienced in Scotland,
Section 3 of the Technical Handbooks contains its own
guidance on cavity insulation. Consultation with Local Authority
Building Standards is advised when considering
appropriate solutions.)
The shortages in PIR have resulted in many and varied
questions about alternative solutions. Where those solutions
are based on other insulation types of proven performance,
and the design can be adapted accordingly to
utilise them, then all should be fine.
But seeking alternative rigid products from within the
same range and thinking they are ‘basically the same
thing’, even though they don’t benefit from certification
for cavity applications, is a recipe for quality issues - and
possible non-compliance with regulations.
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