Cost model: Mixed use

01 / Introduction

The last time mixed use developments were the subject of a Building Cost Model, the world was a very different place: Labour was in government, Lehman Brothers was a financial powerhouse and the iPhone was a mere idea on the desks of Messrs Jobs and Ive.

However, many of the principles covered then could be applied now. Certainly, inner town and city planning policies continue to follow the PPG6 guidelines as well as a desire to create more destination areas for a diverse range of people and businesses. In those 10 years, the force of changing economics has arguably prompted mixed use developments to adopt greater flexibility, with the growth of sub-use classes such as pop-up retail and private rented residential. These changes are responses to the rise of the flexible worker: a generation defined by their use of social media as a key tool of communication, who favour greater flexibility in their work and home lives.

In parallel to this – and perhaps equally defining – is the Thatcherite impact on social housing, which, in part, led to the housing crisis and the recession of 2008-2012. This crisis created social, political and economic events which placed greater importance on flexibility for development success. Evidence of this can be found in the British Property Federation report from last year, highlighting how lease lengths in both commercial office and retail sectors have shortened since the turn of the century.

To cater for these shifting behaviours, the mixed use market has had to adapt accordingly and developers have increasingly adopted a mixed-use template where previously single use would have been deemed sufficient.

02 / Defining mixed use

The definition of mixed use can be varied, stretching from dual use entities (such as residential over retail in a single building) to large scale regeneration projects containing multiple buildings with multiple uses, developed in several phases over significant time periods.

This article will focus on inner city or town mixed use schemes, consisting of a number of buildings connected by a shared infrastructure. Smaller, more urban developments tend to form the majority of mixed used schemes as there are greater opportunities for small plots as opposed to acres for major regeneration within town centres. That said, and possibly with a few exceptions (principally around the scale and phasing of infrastructure), many of the principles covered can be applied to larger mixed-use developments.

Why mix use classes?

Mixed used schemes can be brought about by a number of circumstances. Often it is a combination of a developer’s ambition for a diversified income stream and the need to meet the local authority’s desired balance of use-classes.

Alternatively, it may be the replacement of a use-class already on site, which the development will be displacing, or a Town and Country Planning Act 1990 Section 106 obligation (S.106).

In all cases, the developer’s objective is to ensure that the different use-classes do not hinder one another but instead support and enhance the values of each use within the total scheme.

03 / Considerations for Design and Cost

Mixed use buildings are often some of the most challenging to accurately estimate during the early stages, not least because the interfaces between uses must be understood, whether they exist within one building or are part of the connected infrastructure and public realm between buildings. The mixture and priority of uses can obviously vary, and the cost model will need to have an inherent flexibility to accommodate movements in these attributes over the gestation of the scheme.

Uses can be wedding cakes; numerous layers for a number of uses, like The Shard in London, or connected by shared basements or other shared infrastructure, like a series of separate above-ground buildings such as at the Old Vinyl Factory, Hayes.

Similarly some schemes may share plant while others may not. In some cases, structure, facade or other elements may be shared between the uses leading to an initially arbitrary apportionment between use classes when benchmarking. In short, cost benchmarks often sit some way off what one would normally expect for a single use building. The following considerations will help the initial review.

Configuration

The location and arrangement of uses is a key driver of cost and efficiency. Generally, as the number of uses stacked upon one another increases, so does the cost as it requires extra cores, extra MEP requirements and so on, but it also has a converse effect on overall floor area efficiency as the non-value driving areas such as cores and corridors need to increase to provide the required segregation between uses.

Mitigating the construction cost premium of amalgamating uses within mixed use developments require architectural and engineering intelligence to find smart solutions to elements of design that can support more than one use.

Good examples could be building in the ability for the various uses to share a means of escape, common plant or shared energy strategies.

Full utility

Unlike single-use buildings, mixed-use will, by their nature, have a non-standard set of assumptions for infrastructure such as power or utilities into the building. Where, what and how these come into the building or buildings is crucial for understanding how well the mixed-use development can service all the uses. For example, A3 retail units may need to be designed to offer gas and electricity to serve both traditional gas kitchens and induction hobs. Additionally, and depending on the ownership arrangements, the utilities will need to be easily measurable in order to apportion the service charge with separate meter rooms. This level and multi-service of utilities will usually come at a cost beyond that normally expected for a single-use building, especially in instances where the existing building/plot supplies are lower than those now required. A full appreciation of all the diversions of existing infrastructure, as well as any upgrades to the new building, should be undertaken at the earliest possible opportunity.

Benchmarking the MEP services

In the early stages of a development, it is not uncommon for budgets to be based on benchmark rates and assumptions, which means thought must be given to likely plant requirements and how that plant is to be allocated and shared. It is important to determine whether shared plant is preferred rather than a separated strategy. This will have other implications in terms of the overall efficiency of the development as a separate plant strategy will take up more space within the development area, possibly reducing the lettable area.

In mixed-use projects which rely on shared plant, some of the benchmarked MEP costs can be higher but efficiencies tend to be better compared to separate systems. Overall this can be a source of opportunity from which both assets can take a shared benefit. When setting the budget, it is important to ensure that the initial cost study considers the development as individual uses as well as individual buildings.

Distribution of services

Developments which use retail along the ground plane could have a requirement for kitchen extracts and ventilation to serve the units. If other use-classes are located above or around the retail units, care over the positioning of the ventilation and kitchen riser extract is crucial to ensuring that noise and smell pollutants do not affect the other use-classes. Often it is not possible to place them anywhere other than on the roof and, as such, they need to pass through other uses and be serviceable at intermediate levels. This requires co-ordination of landlord access and riser access through the building.

Structure

There are two primary issues that need to be considered at the outset. First, the use-classes will all have their own preferred structural grid and structural depths (and thus their preferred material and method of construction). Offices and retail spaces crave long span structures, whereas residential will have varying facade lines for day light and tighter spans offering a variety of structural grids.

Depth of the structural zones and floor heights may also vary and this can be more problematic in stacked-use buildings where the traditional repetition of a single use cannot be achieved. To ensure that all these uses get grids appropriate to their needs the frame may require the incorporation of transfer structures. However, this needs to be evaluated with a cost benefit study as transfer structures can add significant cost. Such an analysis will include consideration of the sound and thermal insulation between the uses, among other things.

The optimal number of cores required to service various uses will be a critical study. In some cases cores can be shared, such as in retail and offices as there are opportunities to share the goods lift and some stair access, but this can impact leasing agreements and possibly affect the values if the retail demand becomes too burdensome.

Sharing a core between private sale and social rented residential is possible but problematic. It can be accomplished through the use of access controls and careful architectural planning. Yet it tends to be avoided where possible, and is only really accepted when the efficiencies of a split-core building would be so low that it becomes a worthwhile compromise.

04 / When, where and regional considerations

Time to pay up front

The programme of construction and the release of units or uses to market is initially driven by the sheer size of the development, as well as the connectivity (physical and market) of the respective uses. The drivers for this can be varied such as funding arrangements or when the development requires a positive cash flow.

Towers with stacked uses cannot easily phase the release of uses as they are too closely linked in construction terms, whereas a horizontally-arranged scheme can phase its works over a number of years. If it is intended that a mixed use scheme is to share infrastructure either through Escrow arrangements or via the building of public realm and roadways, this must be factored in to the phased design and upfront budgets, which places pressure on the day one sales or leases to bear the brunt of the costs but can positively impact on future development values. For larger mixed-use masterplans, limiting forward expenditure on major pieces of infrastructure – or matching such investment with income-generating development – is a persistent challenge.

The right spot

“Mixed use gold” has been discovered in recent times through the imaginative redevelopment of constrained sites, and there will no doubt be further and different prospects for realising value through a mix of uses as future building products respond to occupiers developing needs for flexibility and wellbeing. Over the last decade, these opportunities have come with cost and construction implications, broadly because many mixed use sites are found on transport and former industrial hubs. Transport hubs are natural places for mixed use developments as they provide strong connectivity. However, they may require adjustments to existing transport links, possibly adding a road or path and connecting into transport interchanges or transfer structures over train lines. These can add significant enabling works costs to the project, which generally need to be paid for on day one.

Post-industrialised Britain has a number of former factory, gas works and other industrial areas of unoccupied land next to major cities and towns; these could be prime spots for redevelopment. The challenges include remediating the land; making it ready for safe use for habitable dwellings. Successful mixed use developments – as seen at Argent’s Brindlyplace, Birmingham and King’s Cross Central, London – have shown that while these prime spots of land are hugely attractive in terms of location, the success of these impressive schemes has been realised despite the considerable cost to prepare them for redevelopment.

Mixed skill set

Mixed use developments, by their very nature, require a skill set that is broader than single use projects. For example, delivery of residential schemes is subject to different constraints and drivers of success than commercial office and retail.

This is an important consideration in the procurement strategy, with potential contractors requiring the breadth of ability and experience commensurate with the uses. Often the dominant use class will be an over-riding matter, and seeking contractors with strong, proven records in this area will be a prerequisite.

The scale and complexity of the infrastructure works may require specialist input, and the size and phasing of the masterplan will help to determine how the work will be allocated. As with any other construction project, assessing the capabilities, capacity and covenant of the supply chain is a must.

05 / Cost model

This cost model looks at a mixed use scheme, located in the South-east but outside the m²5. It covers 50,300m² in total gross area and comprises 9,000m² of office accommodation, 1,200m² retail units, and 23,500m² residential split between 290 private units and 60 socially rented units.

The layout is two buildings sat on a single storey basement that has one flank as an under croft. The basement houses car parking and plant. Due to the lease and ownership differences of office and residential accommodation, it is assumed that the plant is not shared.

	Total (£)	£/m2	%
Summary
Demolition	2,000,000	40	1
Shared basement	18,080,000	3,054	13
Residential building	92,360,000	2,800	67
Commercial building	25,920,000	2,271	19
Total cost model	138,360,000	2,750	100
1) Areas	GIA	NIA	N:G
Shared basement	5,919	150	3%
Residential building	32,981	24,352	74%
Office building	11,415	8,861	78%
Total	50,315	33,363	66%
2) Wall to floor
Residential building	0.65
Office building	0.49
3) Floor to ceiling heights
Residential building: 3.1m
Office building : 4.1m
4) Buildings with apportioned basement (excluding demolition)
Residential Building	105,790,000	2,830.25
Office Building	30,570,000	2,363.01
Shared basement
Site enablement
Demolition / site preparation	2,000,000	40	100
Site clearance including demolition of existing structures and grubbing up existing foundations (12,346m2 @ £162)
Total - Demolition / site preparation	2,000,000
Shared basement works
Substructure	8,809,000	1,488	49
Excavation; including disposal off site (17,757m³ @ £60)
Pilling mat; including disposal (5,919m² @ £60)
CFA Piles; 600mm diameter, 25m deep, including rig establishment, disposal of pile arising’s off site, trimming tops of piles, pile / integrity testing (681nr @ £6,000)
Pile caps to top of piles along basement floor (1,775m² @ £339)
Allowance for lift pits (14nr @ £10,000)
Reinforced “Caltite” concrete to ground slab to basement; 400mm thick, including blinding, waterproofing, reinforcement, formwork and below ground drainage(5,919m² @ £353)
Retaining walls along perimeter; 300mm RC including king posts, C40 concrete, rebar and formwork (1,615m2 @ £292)
Frame	1,083,000	183	6
Reinforced concrete to frame supporting ground floor slab; columns 1200mm x 800mm at centres dependant on location and parking including Cell core HX S 225mm thick, blinding, reinforcement and formwork (5,919m² @ £183)
Upper floor	1,291,000	218	7
Reinforced concrete to suspended capping slab to basement; including reinforcement, formwork and insulation (5,919m² @ £218)
Roof	0	0	0
No works included for this element
Stairs	30,000	5	0
Reinforced concrete internal stair; Dog leg, half landing, including reinforcement and formwork and aluminium handrail (3flts @ 10,000)
External walls and doors	0	0	0
No works. Included within above ground buildings.
Internal walls	474,000	80	3
Blockwork to enclose plant rooms, storage and demise areas (5,576m² @ £85)
Internal doors	100,000	17	1
Single leaf, metal doors with kick plate to plant rooms, storage and demise areas (50nr @ £2,000)
Internal finishes, fittings, furnishing and equipment	250,000	42	1
Allowance for emulsion paint to block walls within access corridors (7,000m² @ £10)
Access barriers, and signage to car park, allowance only (1 item @ £100,000)
Epoxy paint to floor of plant rooms (2,412m² @ £20)
Vinyl flooring to access corridors including screed, trims and stainless steel door thresholds (324m² @ £98)
All other common parts finishes set out in fit out section
MEP and vertical transportation	1,782,000	301	10
Disposal Installations (5,919m² @ £25)
Water Installations (5,919m² @ £13)
Space Heating and Air Treatment (5,919m² @ £23)
Ventilation systems (5,919m² @ £58)
Electrical installations (5,919m² @ £76)
Protective installations (5,919m² @ £35)
Communication installations (5,919m² @ £71)
Builders’ work	89,000	15	0
BWIC @ 5%
Preliminaries, OH&P and contingencies	3,312,000	560	18
Preliminaries @ 15%
OH&P @ 5%
Design & build risk @ 2.5%
Contingencies
Design reserve / construction contingency	860,000	145	5
Design reserve @ 2.5%
Construction contingency @ 2.5%
Total shared basement	18,080,000	3,054	100
RESIDENTIAL
Residential shell and core
Substructure	0	0	0
All piling and substructure contained within the shared basement
Frame	5,462,000	166	10
Reinforced concrete; 900 x 250mm at centres dependant on location including reinforcement and formwork (14,010m @ £178)
Reinforced concrete shear walls; 300mm thick including C40 concrete mix, rebar and formwork inclusive of kickers (32,981m² @ £90)
Upper Floors	6,520,000	198	11
Reinforced concrete slabs 250mm thick; including reinforcement, formwork and insulation (32,981m² @ £179)
Reinforced concrete roof slab 300mm thick; including reinforcement, formwork and insulation (3,148m² @ £196)
Roof	1,136,000	34	2
Roof coverings to residential building including waterproof membrane and insulation (4,505m² @ £150)
Timber decked terraces to residential building (1,200m² @ £125)
Upstands/parapets/balustrade, fall safe system to maintenance area and lift overruns) (1 item @ £200,000)
Lift over runs, block work with louvered opening, timber entrance doors and weather protective paint to the exposed brick (11 nr @ £10,000)
Stairs	960,000	29	2
Reinforced concrete internal stair to residential building; Dog leg, half landing, total rise per floor 3.2m, including reinforcement and formwork and mild steel balustrade (96nr @ 10,000)
External walls, windows, doors and balconies	16,642,000	505	29
Facing brickwork; Stretcher bond (snapped headers), flush joints, including SFS substrate, insulation and internal plasterboard lining to both buildings (12,551m² @ £450)
Velfac, Aluminium timber composite; 28mm double glazing, including all ironmongery to residential building (9,014m² @ £650)
Extra over allowance for large format glazed doors to retail shop front openings (7nr @ £5,000)
Allowance for louvered plant screens to roofs of both buildings (1 item @ £10,000)
Single leaf timber external doors to both buildings including ironmongery and connection to centralised security system (7nr @ £4,000)
Double leaf timber external doors to both buildings including ironmongery and connection to centralised security system (14nr @ £7,500)
General access scaffold to all areas (21,565m² @ £100)
Balconies installed to all residential units; Includes insulation; timber decking; glazed balustrade; drainage; soffit treatment; thermal break (350nr x £8,000)
Internal walls and partitions	2,487,000	75	4
Partition to residential apartment party walls; Metal stud partition system, 2nr 15mm Gyproc SoundBloc, 100mm insulation taped and jointed (30,489m² @ £80)
100mm blockwork, cut joint at bottom including king posts to retail demises (479m² @ £100)
Internal doors	625,000	19	1
Apartment internal entrance door; Single, including veneered softwood frame, full height side panel, hardwood veneer and ironmongery (350nr @ £1,500)
Internal riser door to residential building; Single, including painted softwood frame, hardwood veneer and ironmongery (83nr @ £600)
Internal basement doors to residential building; Single, fire rated, including painted steel frame, steel faced and ironmongery (20nr @ £2,500)
Internal finishes, fittings, furnishing and equipment	820,000	25	1
Allowance for screed to slabs @ (32,800 x £25)
All other common parts finishes set out in fit out section
MEP and vertical transportation	10,695,000	324	19
Sanitary installations; included in residential fit out works - apartment fit out
Disposal installations (32,981m² @ £21)
Water installations (32,981m² @ £15)
Heat source (32,981m² @ £54)
Space heating and air treatment (32,981m² @ £33)
Ventilation systems (32,981m² @ £17)
Electrical installations (32,981m² @ £81)
Gas installations (32,981m² @ £2)
Protective installations (32,981m² @ £5)
Communication installations (32,981m² @ £63)
Lift installations (10 nr @ average of £109,800))
Builders’ work in connection	535,000	16	1
Builders’ work @ 5%
Preliminaries, OH&P and contingencies	10,905,000	331	19
Preliminaries @ 15%
OH&P @ 5%
Design and build risk @ 2.5%
Total residential shell works	56,787,000	1,722	100
Common area fit out works
Private Residential Common Areas	1,988,000	60	85
Residential lobby including timber veneered MDF core reception desk, folded metal post boxes, plasterboard and emulsion paint to wall finishes, porcelain tile to the floor finishes, suspended plaster board ceiling 115m² @ £1,133)
Wall finish to reinforced concrete and blockwork walls; Plasterboard and paint (9,904m² @ £45)
Wall finish to partitions and linings; Emulsion paint (30,689m² @ £10)
Painted skirting to partitions and linings: MDF skirting and painted (10,532m @ £12)
Floor finishes to lift lobbies, stairs access corridors, hard wearing nylon based carpet to common front of house areas. (7,297m² @ £55)
Floor finishes to basement and plant rooms, epoxy resin paint to floor. (2,253m² @ £20)
Suspended plasterboard ceiling to all common areas ground and above (7,297m² @ £35)
Allowance for signage (1 item @ £30,000)
Allowance for refuse shoots to each core (4nr x £50,000)
Allowance for bicycle store with the basement; Josta double stacked. (30nr x £900)
Allowance for car park fittings including barriers, signage and access control (1 item @ £20,000)
Affordable common areas	355,000	11	15
Residential lobby including plasterboard and emulsion paint to wall finishes, hard wearing carpet to the floor finishes, suspended plaster board ceiling and timber post boxes. 31m² @ £800)
Wall finish to reinforced concrete and blockwork walls; Plasterboard and paint (3,560m² @ £45)
Wall finish to partitions and linings; Emulsion paint (4,176m² @ £10)
Painted skirting to partitions and linings: MDF skirting and painted (2,549m @ £12)
Floor finishes to lift lobbies, stairs access corridors, hard wearing nylon based carpet to common front of house areas. (1,091m² @ £25)
Floor finishes to basement and plant rooms, epoxy resin paint to floor. (837m² @ £20)
Suspended plasterboard ceiling to all common areas ground and above (1,091m² @ £40)
Allowance for signage (1 item £10,000)
Total residential common area fit out works	2,343,000	71	100
Private apartment fit out works
Internal walls and partitions	1,031,000	54	5
Internal partitions to apartments; Metal stud partition system, 1nr 12,5mm Gyproc Wallboard, 25mm insulation, taped and jointed (14,989m² @ £45)
Internal partition to apartment bathrooms; Metal stud partition system, 1nr 12,5mm Gyproc Wallboard, 25mm insulation1 layer of moisture resistant 12.5mm Gyproc MR (7,130m² @ £50)
Internal doors	825,000	43	4
Internal doors to apartments; Single, including painted softwood frame, hardwood veneer and ironmongery (1,000nr @ £825)
Wall finishes	1,855,000	97	8
Finish to bathrooms, en suites and kitchen splashbacks; Ceramic tile (22,009m² @ £55)
Finish to partitions and linings; Emulsion paint (44,621m² @ £10)
Skirting to partitions and linings; MDF skirting and painted (16,526m @ £12)
Floor finishes	1,237,000	65	6
Finish to kitchens and bathrooms; Porcelain tiles, laid on screed (2,881m² @ £90)
Finish to living areas; Engineered timber flooring, wax finish (9,298m² @ £70)
Finish to bedrooms and stores; Carpet (6,972m² @ £47)
Ceiling finishes	1,031,000	54	5
Finish to apartments; Suspended plasterboard ceiling, taped and jointed, primed, sealed and decorated (19,093m² @ £54)
Fittings, Furnishing and Equipment	5,154,000	269	23
Kitchen to private apartments; handless furniture, composite work surface and glass splashback (by others), Franke one & a half bowl undermount sink, tap as Penthouse, LED recess lights, Bosch Whitegoods (290nr @ av. £8,000)
Allowance for cooker hoods to the above (290nr @ £250)
Sanitaryware to private apartments; Bath, close coupled WC pan and seat, pedestal wash hand basin, chrome plated tapware, recessed thermostatic shower mixer with chrome head, shower screen; mirror with lighting; storage under basin; casings; pipe ducts; panels; fixing of fittings and sanitaryware (290nr @ average £5,000)
Fittings to master bedrooms of private apartments; Wardrobe doors and fittings, oak veneer panels (290nr @ £2,222)
Fitting to living area of private apartment; Oak veneered full height shelf unit and mirror (290nr @ £2,300)
MEP	6,588,000	344	30
Sanitary installations; Included Above
Disposal installations (19,152m² @ £26)
Water installations (19,152m² @ £34)
Heat source (19,152m² @ £38)
Space heating and air treatment (19,152m² @ £40)
Ventilation systems (19,152m² @ £38)
Electrical installations (19,152m² @ £93)
Protective installations (19,152m² @ £23)
Communication installations (19,152m² @ £52)
Builders’ work in connection	231,000	12	1
Builders’ work @ 3.5%
Preliminaries, OH&P and contingencies	4,312,000	225	19
Preliminaries @ 15%
OH&P @ 5%
Design & Build Risk @ 2.5%
Total residential fit out works - private apartments	22,264,000	1,162	100
Affordable apartment fit out works
Internal walls and partitions	282,000	65	8
Internal partitions to apartments; Metal stud partition system, 1nr 12,5mm Gyproc Wallboard, 25mm insulation, taped and jointed (3,287m² @ £45)
Internal partition to apartment bathrooms; Extra over the above for 1 layer of Moisture Resistant 12.5mm Gyproc MR (2,682m² @ £50)
Internal doors	164,000	38	4
Internal doors to apartments; Single, including painted softwood frame, hardwood veneer and ironmongery (234nr @ £700)
Wall finishes	329,000	75	9
Finish to bathrooms and en suites; ceramic tile (2,068m² @ £50)
Finish to partitions and linings; emulsion paint (16,945m² @ £10)
Skirting to partitions and linings; MDF skirting and painted (4,679m @ £12)
Floor finishes	235,000	54	6
Finish to kitchens and bathrooms; Porcelain tiles, laid on screed (873m² @ £90)
Finish to bedrooms, living rooms, corridors and stores; Carpet (3,492m² @ £45)
Ceiling finishes	188,000	43	5
Finish to apartments; Suspended plasterboard ceiling, taped and jointed, primed, sealed and decorated (4,365m² @ £43)
Fittings, furnishing and equipment	634,000	145	17
Kitchen to affordable apartments; solid core furniture, hardwearing work surface and glass splashback (by others), Unbranded Whitegoods (60nr @ av. £5,200)
Allowance for cooker hoods to the above (60nr @ £150)
Sanitaryware to private apartments; Bath, close coupled WC pan and seat, pedestal wash hand basin, chrome plated tapware, recessed thermostatic shower mixer with chrome head, shower screen; mirror with lighting; storage under basin; casings; pipe ducts; panels; fixing of fittings and sanitaryware (60nr @ average £4,050)
Allowance for services cupboard, solid core timber plus door; wall hung. (60nr @ 1,167)
MEP	1,175,000	269	31
Sanitary installations; included above
Disposal installations (4,365m² @ £13)
Water installations (4,365m² @ £23)
Heat source (4,365m² @ £45)
Space heating and air treatment (4,365m² @ £26)
Ventilation systems (4,365m² @ £44)
Electrical installations (4,365m² @ £55)
Protective installations (4,365m² @ £17)
Communication installations (4,365m² @ £46)
Builders’ work	41,000	9	1
Builders’ work @ 3.5%
Preliminaries, OH&P and contingencies	711,000	163	19
Preliminaries @ 15%
OH&P @ 5%
Design and build risk @ 2.5%
Total residential fit out works – affordable apartments	3,759,000	861	100
Other works
Utility connections (including basement)	2,013,000	52	28
Allowance for connections to 350 units including meters
Public realm / landscaping	802,000	21	11
Allowance for landscaping to residential courtyard including surface water drainage, paving, planters, plants and furniture (893m² @ £750)
Allowance for reinstatement and kerb line along perimeter (587m² @ £225)
Contingencies
Design reserve / construction contingency	4,392,000	133	61
Design reserve @ 2.5%
Construction contingency @ 2.5%
Total other works and contingencies	7,207,000	219	100
Total residential building	92,360,000	2,800	100
Commercial office shell and core
Substructure	0	0	0
All piling and substructure contained within the shared basement.
Frame	3,420,000	300	18
Steel frame; constructed of universal steel member and inclusive of connections and 90 minute intumescent paint fire protection (1,067tns @ £2,634)
Reinforced concrete sheer walls; 300mm thick C40 concrete including reinforcement at 200kg/m³ and formwork and kickers to sides (2,283m² @ £267)
Upper floor	1,496,000	131	8
Composite holorib and concrete topper to upper floors of residential; 130mm thick, including reinforcement and movement joints (11,415m² @ £116)
Composite holorib and concrete topper to upper floors of residential; 150mm thick, including reinforcement and movement joints (1,431m² @ £120)
Roof	464,000	41	2
Roof coverings including waterproof membrane and insulation (1,427m² @ £150)
Sedum green roof inclusive of soak away to 20% of commercial office roof area (285m² @ £175)
Allowance for photovoltaic cells to commercial office roof (1 item @ £150,000)
Allowance for commercial office roof sundries (lift overruns, mansafes and the like) (1 item @ £50,000)
Stairs	432,000	38	2
Metal internal stair to commercial office building; Dog leg, half landing, total rise per floor 3.8m, including connection and mild steel balustrade (36nr @ 12,000)
External walls and doors	4,045,000	354	21
Facing brickwork; Stretcher bond (snapped headers), flush joints, including SFS substrate, insulation and internal plasterboard lining (1,673m² @ £450)
Schueco, aluminium stick system, including ironmongery to commercial building (3,891m² @ £650)
Extra over allowance for additional structural steel supports to retail shop front openings with timber temporary hoarding put in place (6nr @ £10,000)
Allowance for louvered plant screens to roofs of both buildings (1 item @ £50,000)
Single leaf timber external doors to both buildings including ironmongery and connection to centralised security system (6nr @ £4,550)
Double leaf timber external doors to both buildings including ironmongery and connection to centralised security system (6nr @ £7,500)
Allowance for abseil or davit system to be installed for cleaning and maintenance (1 item £25,000)
General access scaffold to all areas (5,558m² @ £100)
No works. Included within above ground buildings.
Internal walls	283,000	25	1
Blockwork to enclose plant rooms, storage and demise areas (1,837m² @ £85)
Shaft wall to risers (725m² @ £175)
Internal doors	192,000	17	1
Doors to lift lobbies within commercial office building; double leaf, timber veneered inclusive of ironmongery and vision panel. (16nr @ £4,000)
Internal riser door to commercial office building; Single, including painted softwood frame, hardwood veneer and ironmongery (67nr @ £600)
Fire rated doors to commercial office circulation; single leaf including ironmongery (80nr x £1,100)
Internal finishes, fittings, furnishing and equipment	737,000	65	4
Reception fit out including folded metal reception desk, tenant sign board, mat-well backpainted glass feature wall, plasterboard and painted wall, polished concrete floor, suspended plasterboard ceiling with track light LEDs (65m² @ £912)
Washroom fit out including gypsum Gypliner Universal metal framed partition system, using two layers moisture resistant boards and 1 layer of plywood, suspended plasterboard ceiling taped and jointed, IPS duct panelling to walls, porcelain tile splash back, Duravit Happy D toilet pans, wash hand basins with gerbera flush plates and taps. One hand dryer, soap dispenser and toilet roll holder per WC. (250m² @ £2,054)
Lift lobby fit out including plasterboard and painted core wall, suspended plasterboard ceiling, vinyl flooring and signage (175m² @ £584)
Fitting out back of house common area; painted direct to blockwork or plasterboard walls, vinyl to floor and suspended ceiling. (1 item @ £30,000)
Cycle racks to cycle store; josta double stack galvanised steel (20nr @ £900)
Statutory and wayfinding signage (8 floors @ £1,750)
MEP and vertical transportation	4,143,000	363	22
Disposal installations (11,415m² @ £16)
Water installations (11,415m² @ £29)
Heat source - VRF system. Heat source in CAT A.
Space heating and air treatment (11,415m² @ £44)
Ventilation systems (11,415m² @ £29)
Electrical installations (11,415m² @ £108)
Gas installations (11,415m² @ £3)
Protective installations (11,415m² @ £19)
Renewable technology allowance (11,415m² @ £12)
Vertical Transportation (11,415m² @ £103)
Builders’ work	207,000	18	1
BWIC @ 5%
Preliminaries, OH&P and contingencies	3,489,000	306	18
Preliminaries @ 15%
OH&P @ 5%
Design & Build Risk @ 2.5%
Total commercial office shell and core	18,908,000	1,656	100
Commercial office category A fit out
Internal finishes, fittings, furnishing and equipment	789,000	89	16
Plasterboard and painted to core wall; 1nr 12,5mm Gyproc Wallboard, 25mm insulation, taped and jointed including two mist costs (403m² @ £45)
Raised floor system including pedestals, adhesives and all associated fixings and fixtures nominal finished floor height 150mm maximum 200mm (8,861m² @ £37)
Suspended metal tile ceiling including all fixings and access hatches (8,861m² @ £50)
MEP and vertical transportation	2,932,000	331	61
Space Heating and Air Treatment (8,572m² @ £215)
Electrical Installations (8,572m² @ £95)
Protective Installations (8,572m² @ £23)
Communication Installations (8,572m² @ £9)
Builders’ work	148,000	17	3
BWIC @ 5%
Preliminaries, OH&P and contingencies	929,000	105	19
Preliminaries @ 15%
OH&P @ 5%
Design & Build Risk @ 2.5%
Total commercial office category A fit out	4,798,000	541	100
Other works
Utility connections	697,000	61	31
Allowance for connections to 350 units including meters
Public realm / landscaping	278,000	24	13
Allowance for landscaping to residential courtyard including surface water drainage, paving, planters, plants and furniture (306m² @ £750)
Allowance for reinstatement and kerb line along perimeter (215m² @ £225)
Contingencies
Design reserve / construction contingency	1,239,000	109	56
Construction contingency @ 5%
Design reserve @ 2.5%
Total other works and contingencies	2,214,000	194	100
Total commercial office	25,920,000	2,271	100