Rolled
zinc roofing materials
VM Zinc (Umicore) Ltd - Zinc roof for house development on quarry edge
In the heart of suburban Kent, Munkenbeck
and Marshall’s design of Quarry House in Sevenoaks is unusual in
that the structure is built on the edge of a disused quarry. The
design had to accommodate the unusual manmade topography while
blending with homes nearby, so linking of quarry floor and
ground level was achieved using a stepped construction. The
innovative use of otherwise unusable land contributes much to
the four storey building’s credentials. A long-term
environmental problem has been turned into a visually impressive
design, and enhanced by careful and extensive landscaping.
Several types of timber were considered while concepts were
being drawn up, but a combination of larch, from an FSC
accredited source for the structural elements and zinc for the
roof was chosen to provide materials with similar natural ageing
properties. The larch’s silver grey will blend with the gradual
patination of the dramatic, curved zinc profile. Zinc was chosen
for the practicality it offers with complex shaping and
detailing and the low level of energy used in its manufacture.
From ore, it uses the lowest energy level of the non-ferrous
metals - less than half that of copper, and a quarter that of
aluminium.
The existing house is being retained, and with other homes
having an outlook onto the site, the new building’s overall roof
height was restricted by planners. Even so, while giving the
impression of being single storey viewed from ground level, the
curved roof in fact incorporates two floors.
At 5100 sq ft, the design uses the environment to assist cooling
of the building by drawing air over the cliff face. The roof
structure, while providing a major breakthrough in contemporary
design, also provides shading for natural cooling. An internal
box gutter has been used to take rainwater away through the
balcony areas via hoppers and 80mm rainwater pipes, also of
zinc. Two shallow recess gutters were formed at the verges to
prevent water penetrating end panel seams, with weathering
slates soldered to 4 flue outlets on the roof. Fascias and
soffits on the north and south elevation of the building were
also clad in zinc.
Zinc’s attraction in designs of this nature stems in part from
its recycling credentials, 90% of rolled zinc recovered from
roofs and rainwater systems (around 100,000 tonnes each year)
now being reclaimed in Western Europe, for use in galvanising as
well as manufacture of brass and zinc oxide. Though not yet in
widespread use as a roofing material in the UK, zinc’s
sustainable credentials have already established it in common
use for cladding.
All involved feel enthused by the project and feel they have
contributed to a highly innovative, environmentally sensitive
design solution which the client has singled out for particular
praise. Use of terms such as unique are much abused but perhaps
this home within its unusual landscape might lay more claim to
the term than most.
Email: vmzinc.uk@umicore.com