Architect and Builder November/December 2018 | Page 36

to the plastered brick walls. The selection of these
glazing types was to achieve thermal insulation.
There are three double volume areas on the
ground floor, two are reception atriums which are
specifically for the use of the new corporate tenant
and one which is for the retail spine. These double
volume spaces allow for a vertical space creating
a grand reception area and allow for ingress of
natural light from the south.
Due to the limitations of the overall office ceiling
heights double volume areas were created on the
2nd floor within the office space which create
naturally, well-lit, vertical areas which allow for
pause areas. Careful use of materials such as
aluminium panels, performance glazing, and light
coloured wall and floor tiles enhance the iconic
brand value of the public atria.
Structure
All existing concrete structural elements remained,
the addition of new Bondek slab in-fills allowed
for the expansion of the building’s footprint. New
steel framing structures allowed for the fixing of
the curtain wall system as well as the aluminium
cladding. Due to the irregularities on the existing
structure & slab edges it was a challenge to co-
ordinate all the structural elements as well as the
curtain walling and cladding.
During the demolition process the team
encountered downstand beams and other
elements that would not have been noted during
the surveys. This unfortunately required some re-
design of some areas and details to accommodate
existing structures.
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Roof
The existing timber and tiled roof was removed
and replaced with a new lightweight roof structure
supported on a ring beam and girder on the south
elevation of the building. The steel structure was
designed and constructed with structural steel
lattice trusses, girders and lattice columns. This
allowed for the new soft roof to be concealed
behind the façade.
The steel frame principle also allowed sufficient
flexibility to achieve a curtain wall cladding
accentuated with aluminium solid elements as
well as utilising the steelwork at roof level to
support a balcony structure. The design demanded
coordination of the engineer’s requirements, the
curtain wall shop drawings and the detailing of the
solid aluminium elements during the pre-contract
documentation stage and on site construction.
The structure supporting the multi-level façade
also provides vertical support for the roof structure.
This structure was designed and constructed with
conventional I and H structural steel sections. The
exposed steel hangers with intumescent paint
were constructed from hollow sections and these
support the Bondek infill floors. A number of these
columns, in particular on the 4th floor terraces, are
features with no structural significance, however
six of these columns have been designed to
provided vertical support for the roof structure.
HVAC
• An energy efficient variable air volume system
supplies conditioned air from air handling units
located in plant rooms.
Baker Street