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Table 1: Comparison of specification standards for 1960-1970s and 1990s office buildings
Ìý19901960s-1970s
Floor loadings5 kN/m2 + 1 kN/m23 kN/m2
Floor-to-floor heights3.6 - 4.1m2.8 - 3.6 m
Floor-plate size1000-2000m2700-1200m2
Floor-plate width15 - 18m10 - 14m
Table 2: Guide rates
Refurbishment options£/m2 gross floor area
Cosmetic refurbishment270 - 380
Refurbishment of services and internal finishes490 - 700
Extensive refurbishment including alterations to structure and cladding810 - 1050
Table 3: Sensitivity analysis of development yield for three rental incomes
scenario 1scenario 2scenario 3
5100 m2 space at£130/³¾2£160/³¾2£195/³¾2
Anticipated rental income (5100 m2 x rent)£663,000£816,000£995,000
Time to purchase at 7% yield per year (100÷7)14.3 years14.3 years14.3 years
Gross development value (income x years to purchase)£9,481,000£11,669,000£14,229,000
Residual profit/loss (gross development value less total development cost of £11,500,000, see table below)-£2,019,000£169,000£2,729,000
Actual development yield (anticipated income ÷ development costs) 5.77%7.10%8.65%
Table 4: Feasibility appraisal for estimated development costs
£total £
Construction costsÌýÌý
Demolition150,000Ìý
Refurbishment - 6250 m2 @£815/m25,100,000Ìý
External works50,000Ìý
Planning, building regulations fees, survey work, say 1% of construction cost50,000Ìý
Professional fees @ 12%640,000Ìý
Finance costs @ 9% a year based on 50% of construction period415,0006,405,000
Site/existing building purchase ÌýÌý
5500 m2 building @ £540/m22,970,000Ìý
Acquisition costs and fees @ 2%60,000Ìý
Finance costs @ 9% a year420,0003,450,000
Marketing and letting fees Ìý100,000
Development profit @ 12% Ìý1,095,000
Void periodÌýÌý
Finance costs of 9% a year for six months loss of rentÌý450,000
Total development costÌý11,500,000
Cost breakdown
ÌýElement cost (£)Cost/m2 gfa (£)% of total cost
Demolitions and alterations142 53522.812.69
Note: all stripping out and pulling down includes taking away debris and making good to any remaining surfaces
Stripping out existing radiator heating services and boilers etcÌý5500 m2 @£1.50
Stripping out water and waste servicesÌý5500 m2 @£1
Stripping out electrical servicesÌý5500 m2 @£1
Removing floor finishes and hacking off existing screedsÌý5200 m2 @£7
Hacking off existing wall plasterÌý1900 m2 @£3
Taking down suspended ceilingÌý5200 m2 @£1.80
Removing finishes and fittings to toilet areasÌý140 m2 @£5
Removing finishes to stairwell treads and risersÌý130 m2 @£2.50
Removing staircase balustradesÌý150 m @£8
Pulling down block spandrel walls, partition walls and doorsÌý1000 m2 @£4
Pulling down timber and demountable partitions and doorsÌý1200 m2 @£2.50
Removing doors from openings in partitionsÌý50 nr @£10
Removing precast concrete external cladding panelsÌý1700 m2 @£6
Removing galvanised mild steel single-glazed windowsÌý1100 m2 @£3
Removing 300 x 400 mm reinforced concrete upstandsÌý900 m @£12
Removing asphalt roof coverings and screedsÌý1100 m2 @£6
Taking down four-storey steel escape staircase including breaking out foundationsÌý1 @£1,000
Filling to door opening, one brick thick about 1.5 x 2.1 m through 225 mm reinforced concrete wall Ìý5 @£150
Cutting to enlarge opening through half-brick internal wall; new opening 1100 x 2100 mm; existing opening 800 x 2100 mm; forming jambs square; new precast lintel, drypack to existing lintelÌý10 @£100
Cutting out defective reinforced concrete; blast-clean reinforcement and repalce with repair mortar in areas not exceeding 2 m2Ìý25 m2 @£30
Include for taking down external signageÌýallow£500
Cutting to form opening 1.485 x 2.1 m through 150 mm reinforced concrete wall including 15 Ronafix modified mortar to jambs and headÌý2 @£300
Cutting to form openings 1.20 x 1.80 through 150 mm rinforced concrete wall including 15 Ronafix modified mortar to jambs and headÌý40 @£250
Breaking out to form opening 8 x 6 through 300 mm reinforced concrete floor oever entrance foyer including additional framing steelworkÌý48 m2 @£100
Filling in existing duct openings 2 x 5 m in 300 mm reinforced floors including new concrete, formwork to soffit, 10 mm reinforcement and scabbling edges of existing floorÌý10 @£160
Diamond saw cutting new openings 2 x .5 m in 300 mm reinforced concrete floor including 15 Ronafix modified mortar to edgesÌý10 @£670
Breaking out to form four openings 5 x 2.5 m through 300 mm reinforced concrete floor slab for new staircaseÌý50 m2 @£70
Substructure12 2001.950.23
150 mm reinforced concrete ground slab and thinkcening to extended slab dowelled in along one edgeÌý130 m2 @£80
200 x 150 mm deep reinforced concrete upstand kerbÌý180 m2 @£10
Frame142 70022.832.69
Structural steel cantilever extension 700 mm long, one end bolted to frame and perimeter edge beam (1200 m @ 70 kg/m); measure per m2 extended floor areaÌý625 m2 @£160
Structural steel strengthening to one bay for new plant room overÌý2 t @£1,500
Structural steel frame to lightweight plant room enclosure at roof level including plant support steelworkÌý4 t @£1,000
Bracing to new stairshaftÌý4 t @£1,300
Trimming to new riser openingsÌý2 t @£1,500
Fireboard protection to structural steel generallyÌý1100 m2 @£25
Upper floors57 5009.21.08
200 mm reinforced concrete extensio nto upper floor slabs including formwork, reinforcement and dowelling to existing structure 500 m2 @ £80.00200 x 300 mm reinforced cocrete perimeter upstands including formwork and reinforcement Ìý700 m @£25
Roof61 5009.841.16
150 mm reinforced concrete slab to extended roof area including formwork and reinforcement Ìý125 m2 @£48
Warm deck insulation, screed and 19 mm asphalt roofing on felt including work to parapets etcÌý1200 m2 @£30
Lightweight coated steel cladding to plant roomÌý125 m2 @£60
Perimeter edge and gutter detail to plant room roofÌý40 m @£25
Galvanised balustrading to roof perimeterÌý100 m @£110
Stairs29 3004.690.55
Precast concrete dogleg staircase; 3.35m riseÌý4 flghts @£3,000
Chromium-plated balustrades to main staircaseÌý10 m @£300
Chromium-plated handrails to main staircaseÌý80 m @£100
Painted mild steel balustrade to escape stairsÌý20 m @£90
Colour-coated mild steel handrail to escape stairsÌý180 m @£25
External walls1 147 000183.5221.63
Polyester powder-coated aluminium curtain walling system with double-glazed low-emissivity glass and insulated coated aluminium spandrel panelsÌý2900 m2 @£350
Colour-coated aluminium over-cladding, Luxalon or equivalent, on metal grid fixed to concrete and walls Ìý280 m2 @£250
Proprietary independent dry lining as back-up wall to spandrel panelsÌý2800 m2 @£20
Lightweight colour-coated steel wall cladding, Luxalon or equivalent to new plant roomÌý100 m2 @£60
Windows and external doors91 70014.671.73
Polyester powder-coated aluminium double-glazed modular windowsÌý90 m2 @£320
Polyester powder-coated aluminium double-glazed modular fire escape door 1.5 x 2.1 m including frames and furnitureÌý2 @£1,500
Feature entrance screen, doors and canopy in structural glazingÌý75 m2 @£500
Aluminium louvres to roof plant roomÌý40 m2 @£560
Internal walls38 0006.080.72
Note: Additional partitioning to tenants' floor areas excluded ÌýÌýÌý
Shaft wall system to form new service risersÌý220 m2 @£30
150mm blockwork in partitions to new staircase tower and coresÌý210 m2 @£15
100mm blockwork as compartment walls generallyÌý280 m2 @£10
One-hour fire-resisting 70mm Gyproc metal stud partition 3-3.3 m high with 12.5 mm fireboard each side Ìý120 m2 @£35
WC cubicles including doorsÌý35 @£350
WC backwall duct sets; 2200mm high; IPS or similarÌý90 m @£100
Internal doors50 3508.060.95
Veneered flush doorsÌý10 @£300
Laminate-faced solid flush single doors to toilet etcÌý25 @£550
Laminate-faced solid half-hour fire-resisting double doors with vision panels to stairwells and lobbiesÌý15 @£1,250
Laminate-faced solid one-hour fire-resisting double doors with vision panels to stairwells and lobbiesÌý11 @£1,350
Wall finishes72 86011.661.37
Two layers 12.5mm wallboard and skim coat to existing concrete columnsÌý480 m2 @£12
13mm plaster and paint to wallsÌý2400 m2 @£7.50
Tassoglass paper to walls and columnsÌý5700 m2 @£7
Ceramic wall tiling on plaster to toilet walls etcÌý230 m2 @£40
Floor finishes365 40058.466.89
150mm raised-access floor to office areas including carpet tilesÌý5100 m2 @£50
Cavity barriers Ìý800 m2£10
Carpet on concrete make-up to common areasÌý400 m2 @£25
Lightweight concrete make-up to lobby areasÌý900 m2 @£25
Vinyl sheeting to treads and rises of staircases including screeds, nosings and skirtingsÌý190 m2 @£50
Ceramic non-slip tiles on screed to WCs, cleaners' cupboards, kitchenettesÌý235 m2 @£60
Granite feature flooring to entrance foyer on screedÌý50 m2 @£140
Entrance mat and frameÌýItem @£1,000
Hardwood skirtings to common and office areasÌý1600 m @£8
Dustproof sealer to raised floor plenumÌý5100 m2 @£5
Ceiling finishes46 9607.510.89
Plasterboard dry lining to underside of suspended slabsÌý4300 m2 @£7
(Trox chilled ceiling panelled system, 5100 m2, included in heat source space heating and ventilation)ÌýÌýÌý
M/F suspended ceiling to common areasÌý570 m2 @£18
Feature suspended ceiling to entrance foyerÌý48 m2 @£100
Emulsion paint to soffits of stairs and landingsÌý360 m2 @£5
Fittings and furnishings35 000 5.60.66
Allow sum for kitchenette etcÌýÌý£5,000
Internal vertical louvre blindsÌý1000 m2 @£30
Sanitary installation20 0003.20.38
35 white glazed WCs; 5 disabled WCs and fittings; 15 urinals; 35 wash hand-basins in purpose-made vanitory units; 5 cleaners' sinks and 5 stainless steel sinksÌýÌýÌý
Disposal installation30 0004.80.57
Rainwater, waste and soil disposal in PVCuÌýÌýÌý
Water installation41 0006.560.77
Mains supply, hot and cold water in copperÌýÌýÌý
Heating and ventilation1 112 150177.9420.97
Displacement ventilation to office areasÌý5150 m2 @£28
Chilled ceiling installation to office areas including suspended ceiling completeÌý5150 m2 @£160
Perimeter heating to office areasÌý5150 m2 @£22
Pressurisation to cores and staircasesÌý590 m2 @£40
Extract ventilation to toilets and kitchenettesÌý235 m2 @£30
Electrical installations498 50079.769.4
Complete installtion, including recessed light fittings in chilled ceilings; no standby generationÌý100 m2 @£85
Common areas and plant roomsÌý1000 m2 @£65
Lift and conveyor installation50 00080.94
Overhaul of 2 eight-person passenger lifts serving five floors including respraying doors Ìý2 @£20 000
Internal refurbishment of lift carsÌý2 @£5,000
Protective installations62 500101.18
Addressable fire alarm and security systemÌý6250 m2 @£10
Communication installations129 25020.682.44
Centralised building management system for zoned displacement ventilation systemÌý6250 m2 @£15
Data and telephone wiring provision in dado trunkingÌý5100 m @£5
Public address installation; clocksÌýItem @£10 000
Builders' work in connection146 00023.362.75
Associated builders' work in connection with servicesÌýallow 7.5% Ìý
Example spot items (provisional quantities)ÌýÌýÌý
Concrete filling to hole 100 x 100 mm in 150 mm reinforced concreteÌýallow 10 @£25
Concrete filling to hole 1000 x 600 mm in 150 mm reinforced concreteÌýallow 3 @£50
Scabbling surface of existing concreteÌýallow 250 m2 @£2
Reinforced concrete in machine bases and plinths including reinforcement and formworkÌý5 m3 @£200
Cutting chases for conduit 25 x 25 mm; in concreteÌýallow 100 m @£7.50
Cutting chases for conduit 25 x 25 mm; in brickwork/blockworkÌýallow 100 m @£2
Diamond saw cutting rebates in reinforced concrete 25 mm wide x 100 mm deepÌýallow 40 m @£60
Diamond saw cutting holes not exceeding 55 mm diameter in slabs 100-200 mm deepÌýallow 20 @£12
Ditto 200-300 mm deepÌýallow 20 @£18
Diamond saw cutting holes 100 mm diameter in slabs 100-200 mm deepÌýallow 20 @£15
Ditto 200-300 mm deepÌýallow 20 @£20
Diamond saw cutting holes 200 mm diameter in slabs 100-200 mm deepÌýallow 20 @£25
Ditto 200-300 mm deep Ìýallow 20 @£40
Diamond saw cutting holes 200 mm diameter in brickwork/blockwork 100-150 mm thickÌý50 @£18
Cutting away and making good for lighting, socket outlet and fittng outlet pointsÌýallow 100 @£5
Subtotal4 382 405701.1882.64
ÌýÌýÌýÌý
Preliminaries438 29570.138.26
Contractor's management and staff, site accommodation and other preliminary itemsÌýÌýÌý
Contingencies and design reserve482 30077.179.1
Total for scheme5 303 000848.48100
(excluding site works)ÌýÌýÌý
ÌýÌýÌýÌý
ÌýCost/m2 gfa (£)ÌýÌý
Other itemsÌýÌýÌý
Demolitions and alterationsÌýÌýÌý
External scaffolding - allow 2800 m2 @ £126.5ÌýÌý
Stripping out existing air-conditioning systems etc - 5200 m2 @ £21.66ÌýÌý
Removing asbestos cladding board as duct casings etc - typical rate £20/m2n/aÌýÌý
Removing asbestos lagging to pipes; including cleaning pipes - typical rate £40/mn/aÌýÌý
Removing sprayed asbestos to structural beams; including cleaning steelwork - typical rate £70/m2n/aÌýÌý
Raking shoring to adjoining building - typical rate £5/m2n/aÌýÌý
Cleaning of external stone facade - typical rate £8/m2n/aÌýÌý
Cleaning of stained brickwork - typical rate £5/m2n/aÌýÌý
Cleaning of curtain walling or windows - typical rate £5/m2n/aÌýÌý
Repair/refurbishment of curtain walling - typical rate £60/m2n/aÌýÌý
Funigcidal treatment of stonework - typical rate £5/m2n/aÌýÌý
Repair and redecoration or external windows - typical rate £20/m2n/aÌýÌý
Upper floorsÌýÌýÌý
Localised strenghtening of 7.6 x 5.25 m bay with additional fire-protected steel beams bolted with friction anchors to existing concrete frame - 40 m2 @ £650.5ÌýÌý
StairsÌýÌýÌý
Foundations to new attached staircase block 4.6 x 2.5 x 17.5 m high, curtain walling to three sides, roof over and with 4 staircase dogleg flights and finishes as other escape staircases, complete - 1 @ £100,00010ÌýÌý
[The construction of the staircase outside the building footprint will increase lettable area by 45 m2 (0.8%)]ÌýÌýÌý
External walls and windowsÌýÌýÌý
Coated steel Luxalon cladding on metal support rails including 140 mm concrete block back-up wall (2000 m2 @ £80) plus polyester-coated aluminium double-glazed windows (1300 m2 @ £350)-90ÌýÌý
Coated steel Luxalon cladding on metal support rails including 140 mm concrete block back-up wall (2000 m2 @ £80) plus polyester-coated aluminium double-glazed windows with interstitial blinds (1300 m2 @ £500)57ÌýÌý
Heat source, space heating and ventilationÌýÌýÌý
Radiator heating system with localised extract - 5150 m2 @ £60-168ÌýÌý
Fan-coil unit comfort cooling system - 5150 m2 @ £180ÌýÌýÌý
Communications installationsÌýÌýÌý
Central building management services system for fan-coil unit comfort cooling system - 6250 m2 @ £206ÌýÌý
Protective installationsÌýÌýÌý
Single-level sprinklers with heads at 9 m2 - 6250 m2 @ £1012ÌýÌý
Regional Variations
All costs in this model are based on a scheme in Outer London and should be adjusted by the following location factors for schemes in other areas:
Inner London1.08
Outer London1
East Anglia0.85
East Midlands0.83
North0.86
Northern Ireland0.68
North-west0.85
Scotland0.91
South-east0.91
South-west0.84
Wales0.83
West Midlands0.84
Yorkshire and Humberside0.85