Project1_Layout 1 07/05/2013 FLAT ROOFING & WATERPROOFING SYSTEMS
Mastic asphalt terrazzo for
Whilst terrazzo is traditionally perceived as an internal wall or floor finish, when combined with mastic asphalt, it is ideally suited for roofing and
other external applications. Malcolm Grinstead, director of the Mastic Asphalt Council, explains its benefits
There is an increasing need amongst
architects, specifiers and designers to
specify roofing materials, which not only
offer effective waterproofing, durability
and longevity, but an aesthetic element.
This is particularly the case if roofing substrates are
visible such as balconies, walkways and deck areas.
Here at the Mastic Asphalt Council (MAC), we
have seen a trend emerging amongst our members
for the use of mastic asphalt terrazzo in external
applications. Terrazzo is traditionally perceived as
an internal wall or floor finish, but the incorporation
of mastic asphalt makes it ideally suited for roofing
and other external applications.
The long and rich history of terrazzo, with
archaeologists discovering the material in ancient
Neolithic settlements as far back as 8,000 years ago,
is testament to its status as a construction material
that stands the test of time.
Today, modern interpretations of terrazzo
have been created by combining decorative stone
chippings with mastic asphalt, which is then polished
to create infinite possibilities in any design situation.
Some perceive mastic asphalt terrazzo as having
a distinctly ‘retro’ look and no two installations are
ever the same, as the aggregate is exposed as part
of the finishing process. Other finishes can also be
created – such as matte or smooth – as opposed to
the highly polished effect normally associated with
terrazzo. Different visual effects can be created
depending on the size and type of aggregate added at
the mixing point to create a bespoke finish.
Mastic asphalt terrazzo offers the durability and
distinctive features of terrazzo, and consists of a
traditional mastic asphalt base with a modern finish.
Slip and skid resistance can be incorporated into the
wearing course of the mastic asphalt.
Rio Asphalt & Paving Co. has carried out a 330m2
application on the Pope Building at the University of
Nottingham. The multi-purpose deck area has very
heavy footfall and had previously been protected
with mastic asphalt overlaid with promenade tiles.
A refurbishment solution was required due to the
expiration of its natural lifecycle.
The area was refurbished using IKO Permaphalt
roofing, and instead of reinstating the promenade
tiles, IKO Mastic Asphalt Terrazzo was installed
and ground to provide a hardwearing, durable and
decorative finish. The resulting system is ultra low
maintenance and it can simply be re-ground in years
to come to give the roofing finish a new lease of
life. The refurbishment was carried out whilst the
building was still operational, with students and
lecturers still continuing to use the area, so health
and safety was of paramount importance.
072 MAY 2018 RCIMAG.COM
The Pope Building at the University of Nottingham features IKO Mastic Asphalt
Terrazzo, which provides a hardwearing, durable and decorative roofing finish
has also recently
been carried out by
MAC member Bell
Asphalt Company on the
White Knights Building at
Reading University, whereby external mastic asphalt
terrazzo was applied over the university basement
using a system manufactured by IKO. The system
was specified on the basis of its long durability,
waterproofing properties and ability to provide an
Mastic asphalt terrazzo is very popular for roofs,
terracing, balconies, podiums and walkways in
European countries such as Sweden, France and
Germany. European specifiers tend to opt for a
wider range of coloured mastic asphalts for roofing
applications than their UK counterparts, and perhaps
we need to break down the perception that mastic
asphalt is just offered in a standard black finish for
industrial applications. From a manufacturing point
of view, the potential is certainly there to offer a
wider range of colours.
Architects are colour-conscious and the
development of coloured asphalts, created
using suitable colour-stable pigments, and the
incorporation of aggregates would encourage
architects to specify mastic asphalt for a wider
variety of applications. We are finding that specifiers
are realising mastic asphalt’s broad spectrum, and
that they can have bespoke effects such as terrazzo
without sacrificing durability. Mastic asphalt is
perceived by some as an old-fashioned material, but
like many long-lasting materials that have stood the
test of time, it is being re-imagined and modified in
a modern way.
Mastic asphalt terrazzo also comes into its own
when lifecycle costs are taken into consideration,
as there are examples where mastic asphalt has
provided effective waterproofing for some 100 years
or so. Increasingly, specifiers are not just looking at
installation costs, they are considering lifecycle costs
and the lifecycle cost of mastic asphalt is much lower
than competitive roofing systems.
Mastic asphalt terrazzo offers a number of other
practical benefits. It is easy to install and inexpensive
to repair if damaged. Its seamless nature means it
can be easily spot repaired, eliminating the need
for costly wholesale replacement. The flowing
characteristics of mastic asphalt make it easy for
installing contractors to tackle roof surfaces which
are complex, stepped or with multiple protrusions.
In comparison, failure is often found at the point of
detail work in felt or sheet membrane waterproofing
systems, where roofers have cut and fixed the
material to the roof in question.
It is highly resistant to deterioration from
extreme weather conditions and attack from thermal
shock, which are a frequent source of breakdown
in many other types of membrane. Mastic asphalt
can also withstand heavy traffic applications. Its
seamless nature makes it a particularly attractive
option for local authorities, as it helps reduce the risk
of accidents caused by loose slabs or blocks.
Mastic asphalt also offers huge environmental
benefits as it is carbon neutral. It is 100% recyclable
at the end of its useful life and can be broken down
into hardcore or used in roof screeds.