NSC 17
May 19
“The cores were islands in the middle
of the footprint, so we’ve pushed them to
the rear of the building to create more floor
space,” explains Mr Mumford.
One of these cores served both parts of
the building with two staircases that were
separated by a dividing shear wall. The wall
has been removed, most of the core infilled
with steelwork, and new lift shafts installed
around a stability-giving braced steel frame.
Two more cores have been partially
infilled and extended upwards to create
additional floor space, while the remaining
core has been completely infilled.
Much of this work has involved a tricky
process of lifting and installing steelwork
into the existing structure via the open
roof and then down through the floorplates
using openings created by the cores.
“We had to thread the steel beams and
columns into the building by using one of
the site’s two tower cranes and then move
the sections to their final positions with a
block and tackle,” explains Mr Timbers.
The two tower cranes are sat on the
uppermost level of the retained building
and because of a lack of space, their bases
will form part of the new steel-framed
structure. Parts of the crane bases had to
be positioned over column locations and
so once the cranes have been dismantled,
parts of the base will remain as permanent
columns.
Logistics governed the entire erection
programme as the site is very confined with
no room for materials storage and very little
space in which to manoeuvre steelwork into
place.
Because of the nature of the project, the
steelwork package has overlapped with the
demolition programme, albeit in different
parts of the site. This has required a lot of
coordination between trades and a strict
delivery programme, as the project only has
one entrance for materials.
The initial steel construction elements
of the scheme to be undertaken were in the
building’s basement and ground floor.
Originally, the building had two main
entrances that were accessed via nine steps.
They have now been amalgamated into one
entrance and lowered to street level. New
steelwork supports the new ground floor
and creates a large double-height entrance
foyer.
Steelwork contractor Billington
Structures is supplying and erecting
approximately 850t of steel, along with more
than 2,000m of edge protection barriers
from easi-edge.
Sir Robert McAlpine will complete the
project in November.
Commercial
Exposure to heritage
Adding some modern-day
aesthetics to the scheme, the
internal fabric of the completed
building will be exposed, in
order to highlight the industrial heritage
of the building. This exposed design will
include the existing reinforced concrete
slabs and columns on the lower floors,
along with the steelwork in the new areas.
“The new upper storeys utilise cellular
beams allowing integrated service runs
that will be partially hidden behind a
transparent mesh ceiling to create an
industrial yet contemporary aesthetic,”
says Heyne Tillett Steel Associate James
Mumford.
As the frame is exposed, thermal
breaks have been incorporated at roof
level where plant screen and mansafe
posts are fixed down to the new roof
steelwork. There are also thermal breaks
between the precast concrete canopy on
the front elevation and the supporting
steelwork behind.
Steelwork forms a new
rear façade
Parts of the crane
bases will remain as
permanent columns
/Concept_design#Concrete_or_steel_cores
/Braced_frames
/Construction#Tower_cranes
/Construction#Steel_erection
/Construction
/Construction#Edge_protection
/Visually_expressed_structural_forms
/Service_integration