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The brief could be summarised in a few
words: to design a pedestrian bridge
between the tree tops of the Arboretum at
Kirstenbosch. But the project was indeed a
challenging one and is the ‘story’ of how well
the whole project team worked together to
realise the brief.
The walkway was designed to be
‘organic’ and blend unobtrusively into the
forest, while minimising damage to the trees.
To achieve this, a delicate structure, carefully
located between the trees, and finished in
a colour that would blend in was required.
House De Clercq and cottage, Mount Verde
Set in an agricultural estate, surrounded by sugar cane, this
house is a perfect example of what LSFB methods are meant
for. “It is true to the material and does not look like a LSF house
trying to look like a brick home and the early involvement of
the contractor with the design team enabled them to push the
limits of LSFB,” the judges said.
“With a clever mix of a LSF system, with plated LSF joists
and some hot rolled steel they were able to achieve the client’s
desire for an industrial look with thin sharp lines to produce a
world class, beautiful up-market home,” said the judges
Mediclinic, Midstream
Due to the early involvement of the LSF contractor and profile
supplier, the architect was convinced that the design should
include a LSF roof structure to reduce the total load on the
supporting structure.
The Ultra-Span (a pre-fabricated light gauge steel roof truss
system by MiTek) roof structure covers 9 100 m² of the roof
structure and weighs in at almost 68 tons of steel. This comes to
just below 7,5 kilogrammes per square metre, including purlins,
which is extremely light considering some of the roof trusses
span 19 metres with considerable live load and bottom cord
loading requirements. The design also allowed for supporting
100 mm-thick FBI insulation between the truss top chords and
the purlins.
Residential category commendation:
Hennie De Clercq House
The key notion behind the De Clercq house in Cape Town
on the slopes of Table Mountain is that of outside living,
with ‘outside’ incorporating essentially everything on the
ground floor, with as few boundaries as possible. Thus
the single, large living room, encompassing the kitchen
dining and lounge area, opens to the patio on the one side
and onto a wide ‘stoep’ without columns on the other,
bordering on the fynbos garden.
A structure consisting of I-section beams and columns
enables the open plan and the cantilever ‘stoep’, while
carrying most of the storey above. Much attention was
given to the details and finishes of this structure as it
constitutes a key architectural feature.
“Steel was clearly the material of choice, to
satisfy these criteria,” the project team said.
To minimise disruption and damage to
the vegetation, a comprehensive survey of
the area was undertaken. Columns were
located relative to trees, and were not
necessarily placed at the most efficient
structural support positions.
Where it was not possible to avoid a
particular tree, it was either allowed to pass
through the structure, or was tied back to
ensure that it experienced minimum interfer-
ence from the structure.
Winner – residential category:
Zinkwazi Beach House
Located on the steep eastward facing slopes
above the Zinkwazi beach, the judges said
that this gem, using glass window walls
framed by an exposed structural steel
structure, has unimpeded views from the
living spaces.
The expression of this building is
derived directly from the usage require-
ments – enclosed spaces are built in
concrete and masonry and open or trans-
parent spaces are constructed from steel
and glass. “These structural systems define
the aesthetic language of the building and
speak directly to the functional aspects of
the spaces that they enclose,” the project
Joint winners – Light Steel Frame Category:
House De Clercq and Cottage and Mediclinic
Bridge category winner: Kirstenbosch Canopy Walkway
(‘The Boomslang’)
27
CONSTRUCTION WORLD
NOVEMBER
2015