黑洞社区

At-a-glance guide
Project
Radical refurbishment of a 1970s deck-access council-housing block
Client
Nightingale Estate Comprehensive Estates Initiative, London Borough of Hackney
Location
Nightingale Estate, Hackney, east London
Construction budget
拢5.38m exclusive of VAT and fees
拢49,800 a dwelling (total 108 dwellings). Cost was at upper end of medium-rise housing refurbishment
Cost and procurement constraints
Fixed-price contract
Early start on site to spend annual capital budget within the financial year
First-stage tenders returned
October 1996
Contract completion
January 1999

Forms of contract
JCT80 Local Authorities with Quantities, with Contractors Design Portion supplement for roof; Standard Code of Procedure for Two-Stage Tendering

Client鈥檚 brief
Alma House was built in the 1970s as a deck-access slab block with a concrete frame and brick infill. The eight-storey block contained 124 flats built to Parker-Morris standards. After almost 30 years of occupation, the block was suffering from the familiar problems of poor security for tenants and lack of private outdoor space. In particular, the external access decks gave free rein to vandals and petty criminals.
The block was refurbished to improve residents鈥� quality of life. The aim was to provide a greater sense of physical security, to improve flats internally and to add private outdoor space. Other aims were to improve energy efficiency and give another 30 years of life to the building.
Improvements to Alma House were carried out as part of the London Borough of Hackney鈥檚 innovative 拢300m Comprehensive Estates Initiative. The council鈥檚 architecture department produced the initial design for Alma House up to planning submission stage, at which point PRP Architects was appointed architect and project manager.
Residents were consulted throughout the design process, with exhibitions, regular open meetings and drop-in surgeries. In addition, the architect visited each household to discuss residents鈥� needs and their preferences for fittings and finishes.

Project team
Client- Nightingale Estate Comprehensive Estates Initiative, London Borough of Hackney Project manager- PRP Project Services Architect- PRP Architects Structural engineer- Moorehead Consulting Services engineer- Martin Clowes Associates Quantity surveyor- Dearle & Henderson Consulting Planning supervisor PRP Project Services Main contractor- DJ Higgins and Sons

Cost commentary
The client鈥檚 approved budget was fixed at 拢5.38m, or 拢49 800 a dwelling. This puts the project cost at the upper end of medium-rise housing refurbishments, which range from 拢10 000 to 拢50 000 a dwelling.
As such schemes vary widely, comparing costs of specific building elements rather than housing units is more useful in preparing a detailed cost plan. Below are the cost ranges for typical elements in housing refurbishment.

• Cost per unit (拢)
• Concrete repairs and external redecorations500-2500
• Replacement windows and front doors2500-5000
• Internal redecorations1500-3000
• Kitchen and bathroom fittings 2000-3000
• New balconies (each)1500-3500

Project specifics outside these common elements were then 鈥渂uilt on鈥� to these basic elements, to provide a complete estimate for the works.
In the very early stages, it was clear from the initial cost plan that the approved budget would be insufficient to fulfil all areas of the client鈥檚 brief at the proposed levels of specification. A substantial value-engineering exercise was therefore carried out.
As a result, the level of specification of external works was reduced, the new roof was lowered in profile, fewer internal redecorations were carried out and a more economical brand of replacement windows was decided on.
The lowest first-stage tender returned was marginally under budget and was therefore within the expected parameters of the cost plan. Second-stage negotiations took place and a contract sum was agreed.

Procurement
The priorities for the client were an early start on site in the 1996/97 financial year and a fixed-price contract. These were made possible by the adoption of a two-stage tender process using the JCT80 Standard Form of 黑洞社区 Contract for Local Authorities with Quantities and the Standard Code of Procedure for Two-Stage Tendering.
First-stage tenders were invited with a design that was 90% complete. There was enough flexibility to finalise the design and obtain firm prices during the tender period.
The demolition of one of the two sections of the block was let to a specialist contractor in advance of the main contract works. As well as bringing spending forward to an earlier financial year, this served as a pilot project that allowed useful construction lessons to be learned.
After an advert was placed in the European Union鈥檚 Official Journal asking for expressions of interest, six contractors were shortlisted. Of these, DJ Higgins and Sons returned the lowest-price first-stage tender. It also had a track record in housing refurbishment projects with tenants in occupation. Discussions with DJ Higgins continued to the second stage of the tendering process, when it was appointed main contractor.
The main contractor was also made responsible for the design of a wave-form aluminium roof after discussions with the architect and structural engineer. This was covered by the Contractors Design Portion Supplement contract.

Design
The elongated slab block was remodelled by cutting out two full-height sections containing eight flats each. This resulted in three detached eight-storey blocks, each with their own lifts and access decks.
Entrances to the block and refuse stores were reconfigured to provide access directly from the street, rather than from a dark, cramped alley at the rear as had been the case.
The flat roofs were overclad with new profiled aluminium wave-form roofs. Cantilevered balconies were added to both sides of the block, the concrete access walkways and the private flats.
Double-glazed windows and external render to exposed reinforced concrete areas improved the appearance of the block. They are also part of an energy-efficiency package that includes cavity-wall insulation and individual central heating and hot-water systems.
All dwellings were refurbished internally, with new bathroom and kitchen fittings in a variety of finishes, according to the resident鈥檚 choice.
Security was improved by installing CCTV cameras in the entrances and lifts. These are linked to an entry-phone system and can be monitored from each flat, or remotely by an off-site concierge. Also, high-security front doors were added to all dwellings.

Elemental breakdown of contract

Demolitions
One stack of units throughout the full, eight-storey height of the block was demolished. Asbestos found in kitchens and bathrooms was stripped out.
Alterations
Only concrete repairs and associated works are included.
Substructure
Minor foundations and slabs to new bin-store enclosure areas constructed.
Upper floors
Minor extensions added to floors to create refuse enclosure lobbies.
Roof
New profiled aluminium wave-form roof erected above existing flat roof.
External walls
Existing cavity wall insulated, new composite steel and timber balconies and access walkways provided, specialist render to bin-store enclosure walls added.
Windows and external doors
Replacement composite aluminium and timber double-glazed windows installed, as well as replacement entrance doors.
Internal walls and partitions
Walls formed within bin-store enclosures.
Internal doors
All internal doors to dwellings overhauled, including ironmongery; damaged doors replaced.
Internal finishes
Plaster to walls made good, bathrooms and kitchens affected by alteration works redecorated, ceramic wall and floor tiling installed in new bin-store areas, vinyl floor and carpets replaced in all dwellings.
Fixtures and fittings
Kitchen units and worktops replaced in most dwellings.
Services

• Old heating system replaced by combination boilers in all dwellings, services modified to accommodate new heating system, and bathrooms and kitchens refurbished
• Passenger lifts replaced
• CCTV monitoring and entry-phone systems installed
• Baths, wash basins and WCs replaced.

External works

• Provision of on-plot parking, new street lighting and off-street parking
• Entrance road upgraded and soft landscaping carried out to suit new layout.