Pebble Mill variation tests Simons’ flexibility

This massive £17.5m variation, on top of the £21.5m cost of the project’s first phase, was an early test of the adaptability and futureproofing that the architect had built into the design (see below).

“The intention was always to provide flexibility in the design so that extensions could be added on,” explains Bryden Wood director Paul O’Neill. “But the timing was challenging.”

The practice was engaged by Circle in 2014 to design the Pebble Mill hospital. It comprises two adjacent wings, one clinical and one hospitality, joined by a double-height reception and lift core. Initially, Bryden Wood designed a 10,400 sq m building, set out mostly over two levels, including 20 bedrooms, three fitted-out theatres, shell and core, some “fallow space”, plus offices. Simons started on site in April 2017.

But by December, Circle needed more space. This meant adding two storeys above the clinical wing, plus horizontal expansion to the rear, and another storey on top of the hospitality wing, where the building cantilevers out by 7.5m at the front and by 1.5m to the rear. Some 7,600 sq m of extra floor space in total. 

So how was this massive variation incorporated into contract?

The contract form was NEC 3 and was set up from the outset to be flexible, so that instructions on variations from the client could be integrated, says O’Neill. “The design for phase two – the extension – was done outside the NEC 3 contract,” he explains. “We designed up to RIBA Stage 4. Then the design change was instructed by the client through a deed of variation.”

Meanwhile on site, Simons was eight months into building the original design, now known as phase one. “It was a difficult situation,” says project manager Stuart Partlow. “We couldn’t have continued phase one without knowing the client’s plans. We needed to know what to stop, or what to slow down. This was particularly the case with the M&E and steelwork.

“We instructed some steelwork for phase two before the deed of variation was signed. Simons funded it for two months – the steelwork – before we got the official paperwork on the variation. We got an email saying, ‘please get on with it’. It was a written instruction in email. Not an official project manager’s instruction though.”

Simons signed a preconstruction services agreement in December 2017 for the second phase. “We then appointed Bryden Wood as designer through that preconstruction agreement,” says Partlow. In June 2018, the contractor formally received the variation instruction and started phase two.

Above: The original single level of the hospitality wing. Below: Work progresses after the extra level had been added

It was at this point that the benefits of Bryden Wood’s futureproofed design were realised. Extra loading capacity had been designed into both the pad foundations and steel superstructure, including the 12m-long transfer beam in the reception – the longest in the structure – which supports the trusses of the cantilevered hospitality wing above.

The steel frame of the first phase included connections at the end of the vertical members, rising approximately 300mm above the floor slab, to allow for easy connections to the extended structure. “Otherwise we’d have been digging into the concrete slab,” says Partlow. Erection of the frame for phase two was completed in September 2018, taking the total steelwork on the project to 650 tonnes.

The service runs have been sized to allow for extra pipes and cabling, and the roof design provides capacity for M&E plant. “The plant room in the clinical wing hasn’t needed to move, but we’ve switched two air-handling units on to the roof, to free up space, and the chillers above the MRI have also moved on to the roof,” explains Partlow. “This extra load capacity was designed into the structure.”

The lift core is five storeys high, another futureproofing feature of the design, even though the building will only be four storeys with the extension.

“Structurally, there is flexibility for a fifth level,” says Partlow. “However, we have not included the futureproofing features, such as the extensions on vertical steel members, on the fourth floor. The client decided they just wanted to get the hospital built.

“So we don’t actually need the fifth level of the lift core. But by the time the client had decided on the final design, the steelwork had been designed and fabricated, and it would have cost more to have started over and redesigned the lift core for just four storeys. So we are building it out according to the original design.”

All the Simons supply chain came across to phase two of the scheme. “We did test the market in some cases, to demonstrate value,” says Partlow. “The client QS was scrutinising this, particularly Imtech. But it would have been madness to have had two separate M&E contractors for the two phases.”

Drone view of the hospital in November, showing the main entrance with a protected oak tree in the foreground

It has been tricky to manage the two interfacing phases of work, particularly given the addition of the extra levels. “We have tried to programme so we haven’t got someone working above someone else,” says Partlow. “The mantra is safety. The client was obviously keen for fast progress, but under CDM regulations I have to build the project safely and I have to say that to the client. But they are actually happy with the speed of progress.”

The phase two works increased the original construction programme by six months, but the opening of the hospital will only be delayed by three months as some fit-out works will continue while the hospital is operational.

The first sectional handover for Simons comes on 4 March, when Circle’s specialist fit-out contractors arrive. Subsequent handovers on 29 March and 23 April will see the building gradually handed over to the client for staff training. “There is a lot of logistical planning ahead to ensure site workers are kept separate from clinical staff, and Simons retains management of the whole site till the end of April so I will be keeping an eye on the method statements of the Circle contractors,” says Partlow.

The first patients are scheduled to arrive for operations on 4 June, with Simons completing remaining work on upper floors through to contract completion on 5 July.

Bryden Wood designs for future healthcare needs

Buildings can accommodate changing requirements.

Bryden Wood’s work with Circle Health, with hospitals in Reading and now Birmingham, involves “visualising the future of a healthcare asset at the very beginning of the design process”, as director Paul O’Neill puts it.

“Healthcare business models are renowned for rapid and disruptive evolution,” he says. “The brief often evolves quicker than design teams and contractors can keep up with and clients increasingly need to create expandable hospitals.

“At Pebble Mill, the challenging aspect of the brief was achieving a building which can not only expand but also accommodate healthcare services for different patient profiles, within the same envelope.”

The hospitality wing has planning for a fifth level

Each wing was designed to expand either vertically or horizontally. The hospitality wing can reach up to five storeys, while the clinical wing is designed to expand horizontally to provide additional theatres and ancillary spaces, and vertically up to four storeys, for treatment and inpatient areas.

Planning was given for a 19,000 sq m facility, though construction of the first phase would be 10,400 sq m, with the second phase taking it to 18,000 sq m. There is scope for another, 1,000 sq m floor on the hospitality wing.

The adaptive concept was tested when Circle signed a joint venture with a rehabilitation provider and decided to add the phase two extension.

“The limited number of remedial works required on site despite the late instruction of the new brief is a great achievement and proof of the adaptability of structural, services and architectural designs,” says O’Neill.