10 years younger (how to transform a decrepit sink estate into an urban utopia in a single decade)

the renewal of Lee bank started three years ago with the construction of a modest row of four-square terraced houses topped by metal monopitched roofs. In 2013 that quiet overture will climax in a spectacular 20-storey eco-tower. In the intervening seven years, the grim south Birmingham sink estate is to be completely transformed.

That process is well under way. A brand new park is taking root, works of art are springing up and the municipal henge-scape is being enlivened by glass-fronted apartments and a pastel-coloured "turbo funk" mews (shown left). There's even going to be a circus-style block. It may even have a domed roof. Who knows? The project team is on a roll here …

Park Central (the area's new "brand") is challenging the orthodoxies of estates renewal. Every stage adds a new architectural style and another £30-50,00 to the price of an apartment. The project team is free to envisage ever bolder transformations, but as the neighbourhood grows in desirability, the developer has to put some of that value back into improving quality of life for all.

It's too early to declare the regeneration an unqualified success, but already Park Central has been showered with awards, has proved popular with tenants and homebuyers, and it's being touted as a model approach for other estate regeneration schemes.

At its most basic the regeneration involves the demolition of 1350 old homes, the building of 1670 new ones, and the refurbishment of 1200 apartments in tower blocks.

Lee Bank was in dire need of attention, says Dave Thompson, development manager with Optima Community Association, the housing association formed to bring about the transformation of this and four other housing estates in the city (see "Optima's optimism", page 54). "The area was 80% social housing and 80% of the tenants were benefit-dependent. There were a lot of failing businesses, the schools were performing poorly and were underoccupied. Accommodation was in disrepair."

After competitive tendering, the housing association and joint landowner Birmingham council selected Crest Nicholson to develop new homes on almost half of the site. Under the deal, the housebuilder would not own the land, but would have a licence to build. Crucially, the deal also created a framework for increased sales values to be ploughed back into site improvements.

The scheme’s apartments have generously sized wrap-around balconies

At the time the deal was brokered, the housing association was cash-rich. It did not need money for the site but did have a list of things that it wanted done, compiled through consultation with the community and the council. This included affordable housing, improvements to roads, the transformation of open spaces into a central park, a public arts strategy and an accompanying social and economic programme. Under the deal, Crest Nicholson was committed to delivering guaranteed essential works through a development agreement rather than through section 106. Thompson says: "We wanted to take section 106 out of the planning framework and make it part of the delivery agreement.

In a lot of instances, section 106 agreements get diluted and we felt this was the best mechanism for delivery. It also made clear to Crest Nicholson what was wanted."

So as property values rise, the developer has to provide more, not only for Park Central, but also for Optima's other four estates. The price of this to-do list has risen from £14m to £24m so far, but Stephen Stone, Crest Nicholson's chief executive, doesn't mind.

He sees it as a virtuous circle.

The eastern area of the park contains play areas, a lake and a multi-use games area around open parkland with seating and artworks. The western area of the park, which is due for completion this summer, will have an amphitheatre with a paved stage designed by an artist

Detail of the seating in the eastern area of the park.

"When we first looked at the site we thought, here's a prime part of Birmingham with good transport connections, but it's a sink estate. It had every potential to improve and create value.

If the business model is successful, that generates a surplus that can be ploughed back into the area. The project becomes self-perpetuating - you can put more into the park and the infrastructure and create an even more attractive, better quality place."

New homes are a mix of social housing, shared ownership homes and private for-sale units distributed across the site in a tenure-blind way. The site will also have 285,000 ft2 of commercial space ranging from a corner shop to a 120,000 ft2 supermarket.

As development progresses, the homes evolve in step changes. Build costs go up, as do sales prices. The snag with this is that it makes overall control more complicated. George Gardner, director of project architect Gardner Stewart Architects, says: "Masterplanning needs to be more fleet-footed. A masterplan is not a drawing on a piece of paper. It is a process that needs to be robust enough to accept change. It needs to be constantly reassessed."

As a result of that reassessment, Crest Nicholson is now applying for planning permission to develop one of the final elements of the project, a high-rise tower that will have one-, two- and three-bedroom apartments and win environmental kudos for using excess heat from the supermarket.

The change in external finishes from red brick on the early-phase fringe of the site to reconstituted stone surrounding the central park is not driven purely by rising property values. Gardner says: "The brick matches the city centre, but the site as a whole has a series of character areas, from the turbo-funk mews with their blue-rendered live-work lighthouse houses to the parkside classic apartments with their reconstituted stone and glass elevations. The aim is that the housebuilder can access niche markets in a controlled manner, although on the inside, the homes may be the same."

To get maximum value the project team seeks innovations.

Proposals for a high-rise eco-tower on the site. The tower could reuse excess heat from an adjoining supermarket

On the early blocks the metal balconies were designed to double as scaffolding for cladding installation, thereby removing scaffolding costs. Adjustments to the design of the Rigidal metal roofing used on the monopitch and curved blocks also saved money. The architect initially designed a roof with a 28 m radius of curvature, but changed the design to a 40 m radius after Rigidal showed it would make installation easier. A range of build technology is being applied, including steel-frame, timber-frame and precast concrete. A future phase is to adopt volumetric modular.

Buyers and tenants seem to like the 400 homes completed so far. "People were camping out overnight to buy homes here," says Paul Meade, project co-ordinator with Crest Nicholson.

Optima has such high demand for its rented homes that it has closed its waiting list at 700 names.

Existing Lee Bank tenants are being rehoused on the estate and can choose to be near their former neighbours, as long as they select a suitably sized unit. Optima's Thompson explains: "We put up a plan of the housing and say here are all the two-bedroom units, now put a sticker on the home you want. Tenants can then choose whether to put their sticker alongside their former neighbours." The site is unusual for having a high number of houses - 250 will be built in all - and the quantity of social housing will be double the number previously on the site. Houses have been distributed across the site to avoid grouping too many children together.

Both Crest Nicholson and Optima acknowledge that the site had a commercial advantage in its location - nestled between two existing high-value areas, Broad Street and Edgbaston. All they had to do was join them up. Planning policy also helped by allowing higher densities.

Still, Thompson and Stone believe the Park Central model could be replicated elsewhere. Thompson believes the way forward for social housing is mixed tenure and mixed use, and that harnessing private developers creates better deals for housing associations.

Stone agrees: "When you look at sink estates you've got negative land value. They often don't work on paper. It is a matter of being bold enough to believe that you can import land values from an adjacent area. For us the great achievement in this site has been taking a failing sink estate and turning it round to create a vibrant place where people want to live."

Optima is demolishing tower blocks and rehousing tenants in mixed-tenure.

Optima is demolishing tower blocks and rehousing tenants in mixed-tenure, sustainable communities such as Park Central.