JUNE 2017 | 33
Installer Essentials
FIT TIGHT, VENTILATE RIGHT
Andy Swift, national sales manager for ISO-CHEMIE,
considers the effective sealing of building façades,
which can prove to be difficult if failure, particularly
in the form of water leakage, is to be avoided.
While a building façade
should offer some degree of
eye-catching appeal, its main
purpose is to provide weather
protection, and a safe and com-
fortable interior. If this is to be
achieved and long-term perfor-
mance and durability assured, the
materials used need to be carefully
designed, planned and installed.
Facades can come in all shapes
and sizes ranging from heavy
forms of construction through to
brickwork and precast concrete to
lighter structures such as profiled
metal sheet, stick curtain walling,
aluminium and glass screens.
Final specification will have been
decided by the client and the
architect based on the purpose of
the building, the image required,
the design life of the building and
whole life costs including energy
and maintenance costs.
One of the biggest onsite issues
installers can face is how to effec-
tively seal the façade. It doesn’t
matter how much effort has been
spent designing and developing
the perfect joint and gasket if
it’s then undone by an incorrect
installation by an untrained work-
force that has little appreciation of
the performance requirements of a
sealed joint.
And here the choice of sealant
can be critical, requiring careful
consideration and examination to
achieve optimum levels of long-
term sustainability and perfor-
mance.
Sealants, which must adhere
strongly to the materials they
connect, must also be durable and
possess the requisite resistance
qualities if they are to protect
effectively against the elements.
They must also offer compliance
with acoustic and insulation regu-
lations and accommodate move-
ment joints - they need to offer
flexibility without compromise
while ensuring adjacent materials
do not come under stress.
The mantra of ‘fit tight, ventilate
right’ should be adhered to. An
air-tight building with controlla-
ble ventilation is the ideal design.
The construction of commercial
buildings must be tested for
air-tightness in much the same
way as domestic buildings: any air
leaks after a failure can be tested
using smoke pencils, which will
draw smoke from the building
and identify remedial works to
conform to standards. Sometimes,
these failures are through lack of
design input and at other times,
due to contractors not adhering to
designs - usually due to a lack of
understanding of the purpose of
the specified products.
Many sealants are likely to have
a shorter useful life than the life
span of the building unless they
are protected and some provision
should be made for replacing the
sealants within the joints, or over
sealing. Although a significant
proportion of sealants that are
used in façade construction today
are ‘wet’ applied materials based
on synthetic polymers, which cure
to form flexible solids, they do
have their drawbacks: mastics will
harden with time, rendering them
particularly unsuitable for use in
large scale industrial or commer-
cial façade systems.
So, as an alternative to these
‘wet’ solutions, the building and
construction sector is seeing the
emergence of foam-based sealing
strips and tapes. These products
consist of flexible materials, which
are pre-formed in a range of sizes
and sections and mainly rely on
compression, and can be used to
improve the long term sealing of
façade finishes for curtain walling,
pre-cast or in-situ concrete, brick
and block work and composite or
cassette-style metal panels.
The ISO-CHEMIE ISO3 Façade
Sealing system protects the ex-
pansion/movement joints as well
as the junctions between different
materials used in façade construc-
tion against the extremes of hot
and cold and wet and dry weather
together with the physical stresses
caused by building movement.
It can also be used to supply
the relevant level of air tightness
required by the current and pro-
posed changes to the UK Building
Regulations.
The system complies with
regulatory requirements relating
to the different types of facades
including conformity to EnEV
regulations. It also complies
with guidelines laid down by the
industrial association for metal
building constructions (IFBS) for
joint tightness on lightweight steel
constructions.
Passivhaus award-winning sys-
tems BLOCO-One and Winframer
Type 1 are a good solution to
fixing windows to facades when
the external wall is not fitted,
creating an air-tight, structural and
thermally efficient frame to install
windows. BLOCO-One also allows
the window to be installed as a ‘3
in 1’ solution.
Andrew Swift, tel. 07837 337220,
email [email protected]