Sloane Square emporium Peter Jones has definitely seen better days. But up on the roof, a Bovis-led team is running a four-year revamp that will transform the store into a 21st-century shoppers' paradise.
"This is not an ordinary refurbishment," says Terry Spraggett, gesturing out of the window of his site hut towards the cab of a tower crane. His office is perched precariously, seven storeys up, on a temporary steel frame above the roof of the Peter Jones department store in London's Sloane Square.

"This site is so tight, the roof was the only space left to put the site accommodation," he explains.

Spraggett heads the Bovis Lend Lease team working on the project, and he grimaces when it is described as a refurbishment. "It's more of a rebuild," he says.

In 2004, when the project is set for completion, the existing department store will have been stripped back to its steel and concrete skeleton, huge sections of the building will have been demolished and rebuilt and new trading floors will have been added on the building's roof, increasing the sales area by 14%. More than £100m of work will see the existing, slightly tatty building transformed into the jewel in John Lewis Partnership's crown.

The challenge for the project team is to carry out this revamp without closing the store. Spraggett admits that, from the construction point of view, it would have easier to shut the store completely before starting work. However, the client was concerned that many of the store's shoppers would switch allegiance to other emporiums in the area, and that they would have no income from the store while the works were under way.

The existing store is assembled from a collection of five buildings, the oldest of which was built in 1895. However, most of the store dates from the 1930s, when three buildings were constructed over a seven-year period. A final block on the corner of the King's Road and Cadogan Gardens was added in 1964. This piecemeal construction has resulted in different floor levels between buildings, so the store was almost impossible to modernise and rationalise without some serious structural alterations.

This modernisation is made more difficult by the building's distinctive facade.

The parts of the store constructed in the 1930s pioneered the use of curtain walling; in fact, the elevation fronting Cadogan Gardens is the UK's earliest example of this type of cladding system. This innovative facade, plus distinctive interior features such as the large central atrium, resulted in a grade II* listing. This ruled out the option of razing the building and starting again from scratch. The brief for this, the partnership's most idiosyncratic store, was: "To keep the character of the building but to bring it up to contemporary standards." Architect John McAslan & Partners was given the task of producing a scheme that was acceptable to the client and planners at the Royal Borough of Kensington and Chelsea. Over the past 20 years, several refurbishment proposals have been abandoned for failing to meet the requirements of both parties.

Blending the new with the old
Before McAslan started work, it put together a historic structures report on the store. Using John Lewis' rich collection of archive material, the architect was able to show that the building had been modified extensively throughout its life. "We were able to convince the planners that our proposal was true to much of the original design," says project architect Scott Lawrie. The scheme was finally approved in 1998.

Bovis Lend Lease got involved with the project a year earlier. The company had already worked with John Lewis on stores at the Bluewater mega-mall in Kent and in Bristol. "We were brought in at an early stage to produce feasibility studies on buildability and to advise on how the refurbishment could be carried out," says Spraggett. "It was a £100m project handed to us without going to market," he adds.

Bovis Lend Lease proposed three options to transform the building. The first was to refurbish the store through 127 minor construction phases over a period of at least seven years. This would minimise the loss of trading space but, says Spraggett, "was rejected as being too disruptive simply by being too prolonged". The most radical option of "cutting the shop in two" and refurbishing half at a time was rejected, as was the idea of closing the store completely to carry out the works, despite this being the quickest option, because the works would not be quick enough to retain the customers.

"The client opted for a middle-of-the-road option," says Spraggett. This proposal involved the subdivision of the building into three sections: the building's centre section (phase two), a west section fronting Cadogan Gardens (phase three) and an east section comprising the Sloane Square part of the building (phase four). A £10m enabling works package, to allow the building to be split, formed the initial phase.

The contract was originally a fixed lump-sum deal with Bovis as main contractor, but this was converted to construction management to allow Bovis to share design responsibility with the client. Bovis won a separate contract to convert part of John Lewis' main warehouse, around the corner from Peter Jones, into a temporary shop to minimise the amount of floor space out of use at any one time.

1000 clerks of works
Now, more than one year into the project, the client relationship is developing well. "We have to be aware of how the store works so that we schedule major changes and department moves to fall outside peak trading periods like Christmas and Easter," says Spraggett.

To keep the partners at John Lewis – its staff – informed of the progress of the works and their impact on the shop floor, Spraggett arranges weekly presentations. "We have about 1000 clerks of works on this project," he jokes, referring to the shop assistants.

Enabling works – phase one – took place throughout last year. The first challenge was to modify the building services. "The services were one reason the building was falling over," says Spraggett. Problems included sprinklers cast into the concrete floor slab and a heating system based on huge tanks of water crammed into the building's basement. Spraggett says: "These would not look out of place in the British Museum." Next, a new boiler house and transformer room were built on the roof and a computer room was inserted in the basement. Modifications to shop floor services had to be carried out at night, as did 290 departmental moves to allow the building to be split into three. Even the concrete encasing the supporting steelwork around the atrium was chipped away and additional steel plates were welded to them in preparation for the rooftop extension. A three-storey link bridge was added to the outside of the building to give customers access from one half of the building to the other during phase two.

This phase, which split the site in two by crunching through the store from the King's Road to Symonds Street, started last October. "It is the major part of the works," says Spraggett.

It has certainly required detailed construction planning. Temporary acoustic walls have been constructed on either side of the site, from the basement to the roof, to isolate the works from the public. Even with the partitions in place, noisy work has to stop at 9.30am – store opening time. And a section 60 noise restriction order prohibits noisy work outside normal working hours and at weekends. This means it has to be squeezed into 90 minutes before 9:30am.

One of the first tasks in phase two was the demolition of the 1895 building's interior, without touching the 86 m long facade. Once enough space had been cleared, a tower crane was shoehorned into the island site to speed demolition. "There is only room for one crane," explains Spraggett, "so we've got the tallest freestanding crane in the UK." Demolition of existing structures was extremely difficult because the building is constructed on an island surrounded by busy roads. The crane was used to drop plant and excavation equipment through holes in the structure to speed demolition. And, because there was nowhere to store demolition waste, skips had to be craned on to the floors where they were filled before being craned on to lorries for disposal.

One of the biggest problems faced by Spraggett is asbestos removal. Spraggett speaks in hushed tones, even in his site hut away from the public, when he explains how the air is constantly monitored for the presence of asbestos. Once asbestos is located, samples are processed in a laboratory Bovis has set up on site, so that a quick decision can be made on the most appropriate method of its removal.

Once the site was cleared, a steel frame was constructed to extend the atrium up from the first and second storeys to the roof seven floors above. New steelwork was added on the roof extending over the phase three and four areas as part of the extension to the sales floor.

The next construction landmark will be the casting of new concrete floors, due to be completed by the end of March. Then the pressure will be on Spraggett to install 14 new escalators to allow shoppers access to the upper floors once Spraggett's team starts phase three.

The phase two works are set for completion next summer. But, says Spraggett, the shoppers of Sloane Square may well be back at the heart of Peter Jones before then. "Our strategy was right from the start," he says. "We're on programme and within budget and we expect to be able to predict an opening date later this year."