Cost model: Office design | Features

Relative cost of steel structures
Grid	Structure cost (index)	Total cost (index)
7.5 × 9 m	100	100.0
9 × 9 m	104	100.3
9 × 12 m	115	100.8
9 × 15 m	125	102.7

Location factors
Inner London	1.00
Outer London	0.94
South-east	0.92
South-west	0.85
East Midlands	0.81
West Midlands	0.84
East Anglia	0.86
Yorkshire & Humberside	0.80
North-west	0.83
Northern	0.83
Scotland	0.81
Wales	0.82
Northern Ireland	0.68

Shell-and-Core Works
	Element cost	Cost/m2 gfa £	% of total cost
Substructure	2,648,600	124.35	7.52
Allowance for de-watering excavations item @ £100,000
Break out existing slabs, piles, obstructions and allowance for probing/testing item @ £300,000
Foundations; bored piles 600-1500 mm diameter with under-ream, 16m long, ground beams, pile caps 1,940m2 @ £300
Allowance for mini piles and other works to boundary walls item @ £150,000
Allowance for piling platform and access ramp item @ £35,000
RC basement slab 300 mm thick, including waterproofing, excavation and disposal 1,940 m2 @ £150
RC mat slab 1200 mm thick, including waterproofing, excavation and disposal 200 m2 @ £450
Reinforced concrete retaining walls 300 mm thick; temporary supports 600 m2 @ £275
Reinforced concrete ground-floor slab 130 mm thick on profiled metal sheet decking 1760 m2 @ £60
Allowance for car park ramp, construction joints between new/existing work, slab, thickenings to stair foundations, lift/escalator pits, drainage channels, concrete transfer walls, etc item @ £300,000
Allowance for crane base including base piles item @ £30,000
Allowance for attendance on archaeologists and movement monitoring item @ £100,000
Allowance for below slab drainage item @ £250,000
Allowance for all other items and sundries item @ £150,000
Frame	4,047,500	190.02	11.50
Structural steel frame, based on 70 kg/m2 overall of gia including fittings 1,350 t @ £1,550
Extra for built up beams 360 t @ £250
Allowance for secondary steelwork, based on an extra 5 kg/m2 100 t @ £2,000
Extra for concrete encased beams at ground floor item @ £60,000
Fire protection to steel frame (average rate but generally 90 mins intumescent paint) 1,350 t @ £600
Reinforced concrete core walls average 350 mm thick 3,300 m2 @ £200
Allowance for other structures (such as within plant rooms, lift motor rooms) item @ £100,000
Allowance for expansion joints and other sundries item @ £50,000
Upper floors	1,220,800	57.32	3.47
Lightweight reinforced concrete 130 mm thick on profiled steel decking 17,430 m2 @ £60
Allowance for upstands, plinths, bund walls, metal plate walkways, supports, etc item @ £175,000
Roof	478,400	22.47	1.36
Lightweight reinforced concrete 200 mm thick on profiled steel decking 1,760 m2 @ £75
Proprietary roof finish, with paving slabs, insulation and ballast 1,760 m2 @ £140
Allowance for insulation to exposed soffits and acoustic treatment item @ £50,000
Allowance for upstands/plinths, hatches/ladders, safety hooks and latchways item @ £50,000
Stairs	535,000	25.12	1.52
Steel pan staircases including concrete infills to stair treads, painted mild steel balustrades and handrails (basement to roof; 13 floors; 53 m; 26 flights) 2 @ £190,000
Ditto, basement to ground: 2 flights 2 @ £15,000
Feature entrance stairs item @ £75,000
Allowance for stairs/cat ladders and safety rails to plant rooms item @ £50,000
External walls	7,653,500	359.32	21.74
Feature wall at ground level item @ £500,000
Internally ventilated double wall facade: unitised system incorporating double-glazed outer skin,
single-glazed inner skin with opening lights, integral louvre blinds 8600 m2 @ £700
Stainless steel screening to plant enclosures 450 m2 @ £450
Glass entrance canopies; cantilevered from building 250 m2 @ £1000
Allowance for stainless steel detailing, articulations, etc item @ £450,000
Extra for louvres item @ £25,000
Blockwork walls at roof level, including wind posts 60 m2 @ £100
Allowance for visual mock-ups and performance tests item @ £200,000
Windows and external doors	200,000	9.39	0.57
Extra over cladding for single and double doors, including disabled pass doors item @ £50,000
Extra over cladding for revolving doors 2 @ £40,000
Extra over screen enclosures for single and double doors item @ £10,000
Electrically operated galvanised steel roller shutter to loading bay and car park ramp 2 @ £15,000
Metal doors in service areas item @ £30,000
Internal walls and partitions	1,614,000	75.77	4.58
Insitu concrete walls in basement, etc 540 m2 @ £150
Fairfaced blockwork walls at basement, ground levels and roof levels 3,500 m2 @ £80
Curved blockwork entrance feature wall 300 m2 @ £170
Drylined core walls 6950 m2 @ £80
Extra for double thickness drylined core walls 1,000 m2 @ £80
Allowance for other walls/partitions to plant areas, additional walls and detailing item @ £150,000
Glazed screen to shopfronts 70 m2 @ £800
Veneer-faced WC cubicles/doors; access panelling 90 @ £4,000
Internal doors	377,000	17.7	1.07
Single timber doors 140 @ £1,500
Double timber doors 30 @ £2,500
Profilex riser doors 35 @ £1,200
Other doors: plant rooms; additional access door hatches item @ £50,000
Wall finishes	1,033,400	48.52	2.94
Stone cladding to main entrance lobby 880 m2 @ £350
Back-lit glass panelling on steel frame in main entrance lobby 150 m2 @ £1,000
Paint to fair face block walls 2,150 m2 @ £5
Plaster and paint to blockwork/concrete 3,820 m2 @ £15
Skim coat and paint to drylined walls 1,700 m2 @ £8
Stone cladding to toilets 450 m2 @ £275
Granite cladding to lift lobbies 800 m2 @ £375
Lift architraves item @ £70,000
Floor finishes	779,600	36.60	2.21
Granite/stone tiles to main entrance lobby and lift lobbies 1250 m2 @ £350
Stone tiles to toilets including membrane, waterproofing, screed and skirtings 440 m2 @ £250
125 lightweight screed to circulation and core areas to make up levels 1,280 m2 @ £30
Durable sealant/hardener to car park, loading bay and plant rooms 1,140 m2 @ £80
Vinyl flooring to security areas item @ £7500
Entrance mats and matwells item @ £40,000
Allowance for lining to car park and loading bay item @ £25,000
Allowance for other floor finishes item @ £30,000
Ceiling finishes	509,800	23.93	1.45
GRG feature ceiling to main entrance lobby, including detailing in areas 870 m2 @ £300
Feature drylined ceiling to lift lobbies 380 m2 @ £140
Metal tile suspended ceilings to toilets 440 m2 @ £75
Painted plasterboard on metal framing to corridors, circulation area, etc 840 m2 @ £50
Insulation to car park/loading bay soffits 1030 m2 @ £20
Allowance for access panels, bulkheads/other detailing and paint to some plant room soffits,
other sundry ceiling finishes item @ £100,000
Fittings/fitting out (excl. loose furniture)	537,500	25.23	1.53
Allowance for main entrance reception desk and security desks item @ £80,000
Stone vanity tops in toilets with holes for basins/taps and mirrors behind 70 m @ £1,750
Toilet fittings including soap dispensers/tanks, roll holders, paper towels, coat hooks, etc 90 @ £500
Extra for fittings to disabled toilets 10 @ £1,500
Allowance for rubbish compactor item @ £25,000
Allowance for column guards, bollards/crash rails to loading bay/car park, cycle racks, car park traffic management system, statutory signage and other fittings item @ £250,000
Sanitary appliances	83,000	3.90	0.24
WCs, basins, cleaners sinks, urinals (average rate per point) 200 @ £370
Extra for disabled toilets 10 @ £900
Disposable installations	234,700	11.02	0.67
Rainwater disposal system 21,300 m2 @ £3
Soil, waste and vent installation 21,300 m2 @ £7
Extra for drainage to retail areas Item @ £10,000
Condensate drainage 21,300 m2 @ £0.50
Water installations	233,000	10.94	0.66
Cold water services: incoming, storage, pumps, distribution, etc. 21,300 m2 @ £6
Hot water heaters and distribution 21,300 m2 @ £3
Water services for vending area 21,300 m2 @ £1
Supply to retail areas item @ £20,000
Space heating and air treatment	1,448,200	67.99	4.11
Gas installation item @ £20,000
Boilers item @ £65,000
Air handling units 21,300 m2 @ £8
Chillers 21,300 m2 @ £13
LTHW heating installation including pumps and boiler flues (dilution) 21,300 m2 @ £18
Air conditioning installation including fans and ductwork 21,300 m2 @ £11
CHW installation including pumps and riser pipework 21,300 m2 @ £14
Ventilation installation	481,700	22.62	1.37
Toilet extract installation 21,300 m2 @ £4
Smoke extract ventilation 21,300 m2 @ £3.50
Ventilation to plant room, lift motor rooms, refuse area, etc. item @ £45,000
Car park and basement ventilation 21,300 m2 @ £7
Stair and lobby pressurisation 21,300 m2 @ £6
Electrical installations	1,447,000	67.93	4.11
HV Switchgear and transformer 21,300 m2 @ £8
LV distribution and rising busbars 21,300 m2 @ £23
Power to mechanical plant 21,300 m2 @ £2.50
Small power installation 21,300 m2 @ £3
Lighting, emergency lighting 21,300 m2 @ £11
Lighting, emergency lighting to car park and basement areas 21,300 m2 @ £3
Enhanced lighting in lobby and other areas item @ £50,000
External building lighting item @ £160,000
Standby power installation, including oil system item @ £140,000
Earthing and bonding 21,300 m2 @ £1
Lifts and escalators	1,472,000	69.11	4.18
Passenger lifts, 21-person serving 14 floors 6 @ £170,000
Goods lift serving 14 floors 1 @ £190,000
Car park lift 1 @ £50,000
Fire fighting lift 1 @ £140,000
Enhanced lift car finishes 6 @ £12,000
Protective installations	298,200	14.00	0.85
Sprinkler Installations: tanks, pumps, risers etc. 21,300 m2 @ £11
Dry riser installation 21,300 m2 @ £2
Lightning protection 21,300 m2 @ £1
Communications installation	355,200	16.68	1.01
Fire alarm installations 21,300 m2 @ £12
Containment for BMS, security, data, etc 21,300 m2 @ £2
Landlord security provisions 21,300 m2 @ £1.50
Disabled alarms item @ £25,000
Special installations	626,900	29.43	1.78
Building management system 21,300 m2 @ £13
Allowance for facade cleaning equipment item @ £350,000
Builder’s work	341,000	16.01	0.97
Builder’s work in connection with services installations, including machine bases, steel framework, firestopping, etc: overall allowance 21,300 m2 @ £16
Preliminaries and contingencies	6,547,000	307.37	18.59
Construction manager’s organisation, staff costs and fee @ 17% item @ £4,871,000
Design reserve and construction contingency @ 5% item @ £1,676,000

TOTAL SHELL-AND-CORE COSTS	35,203,800	1652.74	100.00

Fit-out Works
	Element cost	Cost/m2 gfa £	% of total cost
Wall finishes	103,300	4.85	1.83
Emulsion paint finish to office side of core walls 1,770 m2 @ £5
Column casings, including paint, sub-frame, etc 1,180 m2 @ £80
Floor finishes	540,200	25.37	9.57
Dust sealer to concrete slabs 14,600 m2 @ £1
Medium grade fully accessible raised floor, metal faced plycore; 600x600 tile size, 150 nominal depth; including fire barriers 14,600 m2 @ £36
Ceiling finishes	657,000	30.85	11.64
Concealed grid metal tray suspended ceiling to office areas; acoustic quilt & fire breaks 14,600 m2 @ £45
Fittings / Fitting out	14,600	0.69	0.26
Allowance for statutory signage 14,600 m2 @ £1
Space heating and air treatment	1,722,800	80.89	30.53
Four-pipe fan-coil units 14,600 m2 @ £18
Distribution ductwork, grilles etc 14,600 m2 @ £40
CHW installation; insulation 14,600 m2 @ £27
LTHW installation; insulation 14,600 m2 @ £22
Condensate installation; insulation 14,600 m2 @ £11
Electrical installations	890,600	41.81	15.78
Lighting and emergency lighting installation 14,600 m2 @ £44
Distribution boards 14,600 m2 @ £4
Earthing and bonding 14,600 m2@ £2
Lighting control 14,600 m2 @ £7
Small power to fan coil units 14,600 m2 @ £4
Protective installations	219,000	10.28	3.88
Sprinkler protection to offices 14,600 m2 @ £15
Communications installations	153,300	7.20	2.72
Fire alarm installation 14,600 m2 @ £10.50
Special installations	219,000	10.28	3.88
Building management system 14,600 m2 @ £15
Builders’ work in connection	73,000	3.43	1.29
Builders’ work in connection with Category A services 14,600 m2 @ £5
Preliminaries and contingencies	1,050,200	49.31	18.62
Construction manager's preliminaries, staff costs, fee @ 17% item @ £781,000
Contingency and design reserve @ 5% item @ £269,200

TOTAL category a fit-out COSTS	5,643,000	264.96	100.00
Note: The cost of the Category A fit-out £/m2 (NIA) is £386.50