Specifiers Journal 2016

Prefabricated three dimensional façade design and
construction using prefabricated precast concrete
Modern contemporary building
designers are demanding buildings
requiring a high degree of relief
in the surface of the façades. This
usually involves constructing the
buildings in a traditional method
where an internal structural layer is
built, a cavity is left which can then
contain thermal insulation (If it is
not already installed in the structural
layer as in structural framed steel
systems); the external elements are
then installed.
This system has in the past worked
very well, now however, where
Building Regulations have started to
demand higher thermal standards
combined with the increasing
deleterious effects of the Y factors,
(the thermal bridges associated
with fixings such as wall ties and
cladding supports) means that
attempting to achieve the lower U
values demanded by the regulations
is becoming increasingly difficult.
Wall thicknesses are increasing and
this creates a number expensive
building solutions. There is now
however an alternative way of
keeping these costs in check and
reducing the overall wall thickness.
A revolution had been occurring in
the concrete industry allowing the
external façade to be installed in
one process. This can be achieved
either by pouring in place on site
or more commonly by installing
8 SPECIFIERS JOURNAL
prefabricated precast concrete
panels to form both the structure
and the visible architectural finish
complete with windows if required.
Whilst this method of construction is
not new to the construction industry;
hospitals, schools and hotels as well
as industrial buildings have been
built for many years all over the
British Isles. The new development
is now enabling a sculptured relief
in the façade, completely thermally
broken. No longer does a thermally
broken concrete sandwich panel
have to flat and boring.
The installation of the complete
wall using a series of panels in one
operation, using the Thermomass
thermally broken connectors
has enabled U values as low as
0.10 W/m 2 K to be achieved and
lower if required, the real innovation
came with the development of
the X connector technology from
Thermomass. Designed initially
to achieve composite reaction
between two wythes of concrete
its has exceptional strength
characteristics proving to be a real
asset when insulation thicknesses
are having to be increased and
when additional deep rustications in
the external façades are becoming
a commonly specified requirement.
The over all effects are stunning,
making good use of natural products,
creating completed project that is
highly sustainable, has increased
thermal mass and comfort yet
enabling projects to be delivered on
time and to budget.