Cost
Table of key costs (£/m2 GIFA), for City of London Office Building (Q4, 2017)
Elements Steel cellular composite Post-tensioned concrete flat slab
Substructure £87 £92
Frame and upper floors £423 £458
Total building £2,549 £2,687
Any estimate that falls outside these ranges
should be taken as a signal that the design
should be looked at closely to determine why.
Location of a project will be a key factor in
establishing price and indices are used to allow
for adjustment of cost data between regions.
The variations in these indices, such as the
BCIS location factors, provide a clear indication
that market conditions differ between regions
to a significant extent, which is a key
consideration for cost analyses to take into
account.
NSC 33
BCIS rates for different locations
as of Q4 2017 (UK Mean = 100)
Location BCIS Index
Central London 126
Manchester 104
Nottingham 104
Birmingham 102
Liverpool 99
Leeds 97
Newcastle 92
Dublin 92*
Glasgow 92
Cardiff 85
Annual Review
Steel comes to One Kingdom Street
AECOM’s cost comparison of an actual
office building looks at the steelframed,
10-storey, grade A central
London office at One Kingdom Street near
Paddington railway station which was
completed in 2008.
The building comprises 10 storeys with two
basement levels and plant housed at roof
level. It incorporates clear spans of 12m x
10.5m and was built with three cores, with an
open atrium on the main core.
This cost comparison updates cost models
developed in 2010 when the building was part
of the Target Zero study to provide guidance
on design and construction of sustainable, low
and zero carbon buildings. Costs current in the
fourth quarter of 2017 are the latest used for
the new Costing Steelwork study (see table
alongside).
The 40m high building is rectilinear, with a
footprint of 81m x 45m. The western half of
the building is partly constructed on a podium
transfer structure that encloses works access
for the Crossrail project.
It is founded on 750mm diameter bored
piles with in situ pile caps laterally restrained
by ground beams. The piles are the same size
as those used to support the Crossrail podium
to reduce the potential for differential
settlement.
Two structural options were assessed with a
concrete-framed post-tensioned concrete flat
slab for comparison. The analysis shows the
steel composite solution as 8% lower than the
concrete alternative for the frame and upper
floors, and 5% lower for the total building.
Costs benchmark framed
AECOM has provided costs based on
the structural framing of a commercial
office development in central London,
expressed as a cost/m2 on Gross Internal Floor
Area, to be used as a benchmark. A range of costs
is indicated for the key costs drivers as these can
very between projects for a variety of reasons, as
detailed in the full report.
To use the table first identify which frame type
most closely relates to the project being costed,
select and add the proposed floor type and add
fire protection if required.
Indicative cost ranges based on gross internal floor area (Q4,2017)
Type Base index 100 Notes
Frame
Steel frame to low rise building £97-117/m2 Steelwork design based on 55kg/m2
Steel frame to high rise building £163-185/m2 Steelwork design based on 90kg/m2
Complex steel frame £185-218/m2 Steelwork design based on 110kg/m2
Floor
Composite floors, metal decking
and lightweight concrete topping
£60-91/m2 Two-way spanning deck, typical 3m span,
with concrete topping up to 150mm
Precast concrete composite floor
with concrete topping
£97-137/m2 Hollowcore precast concrete planks with
structural concrete topping spanning
betwen primary steel beams
Fire protection
Fire protection to steel columns
and beams (60 minutes’ resistance)
£14-20/m2 Factory-applied intumescent coating
Fire protection to steel columns
and beams (90 minutes’ resistance)
£16-29/m2 Factory-applied intumescent coating
Portal frames
Large-span single-storey building
with low eaves (6-8cm)
£73-95/m2 Steelwork design based on 35kg/m2
Large-span single-storey building
with low eaves (10-13cm)
£83-113/m2 Steelwork design based on 45kg/m2
* AECOM index