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Located in a former 1970s tax office just behind Liverpool’s historic waterfront, Roco may offer a template for vacant central business space in cities across the UK. The former open-plan workspace, 70m long and 12m deep, has been reconfigured as 120 one and two-bedroom apartments, opening either side off a central corridor.

The ground and seventh floors offer various shared spaces including work areas, a large kitchen, cinema room, gym and treatment rooms. On the seventh floor a planted roof terrace looks out over Tate Liverpool, the Three Graces and the Mersey beyond.

The starting point for this reinvention, however, was the first-floor concrete slab. “When we first visited, our immediate impression was that it was just a very dated, typical office from that period,” says Vincent Hon, the project architect for SODA Studio. “The ceiling heights were quite low, it still had the original suspended tiles, and all the finishes were very tired.” As they removed the ceiling tiles, however, they found a waffle slab, still in good condition. “It was a beautiful concrete structure,” says Hon. “That really began to inform the design moving forward.”

With just 2.7m to play with from slab to slab, the designers could maximise headroom just by cleaning the waffles and making them a defining interior feature. All high-level services have been left exposed and surface-mounted, with can lights at the centre of each 600mm x 600mm waffle. The spaces below follow the same logic, with the architects being led by what they discovered as they uncovered the structure. “Once everything was stripped out, we adjusted the design to suit the waffle grid,” says Hon.

“Where there was a section of flat slab, that’s where we’d put partitions.” The regular spans, with 7m-wide bays either side of a central spine of columns, were another guide: “It gave us the flexibility to play around with layouts.” The central columns have been encased in a timber “activity wall”, which stretches the length of the building.

This single piece of joinery incorporates surfaces, storage and seating, subtly delineating spaces within the open ground floor. SODA Studio has kept structural interventions to a minimum, simply making additional penetrations in the lift and stair cores to improve access and circulation. Windows have been replaced with double-glazed units and insulation added to the inside of the envelope. The original brick skin has been retained. “Sustainability-wise and design-wise, the approach was, let’s work with what we’ve got.

We’ve got a beautiful structure as it is. If we’re adding or taking away from the concrete fabric, that kind of defeats the purpose.” One result of this is that the flats are unusually shaped – the long floorplate, split in two by a central corridor, has generated single-aspect living spaces that are about 5m deep from front door to facade. “Although this was something we needed to design around in some ways, it did mean that natural light and ventilation could penetrate all the way to the back of the flats,” says Hon. The fully furnished apartments are styled in muted tones, with separate bedrooms and living areas.

The new uses push the concrete frame hard, not least on the seventh floor, which houses the gym and roof terrace. With no archive drawings to consult, detailed structural analysis was needed to make sure that the slab could take the weight of gym equipment and deaden any impact noise to the flats below – a particular concern as the waffles are as little as 100mm deep. With ceiling heights already at a bare minimum for exercise machines, a floating floor was ruled out; instead, acoustic impact mats have been installed on top of the slab.

Some compromises are inevitable when a building changes use as dramatically as Roco has. But if the weight machines look a little cramped on the seventh floor, it’s a small price to pay for the neighbouring terrace. Here, residents can sit out in the landscaped courtyard, or lie back in one of three hot tubs, take in the views, and co-live the good life. CQ 289, Winter 2024

THE APPROACH WAS, LET’S WORK WITH WHAT WE’VE GOT. WE’VE GOT A BEAUTIFUL STRUCTURE. IF WE’RE ADDING OR TAKING AWAY FROM THE CONCRETE FABRIC, THAT KIND OF DEFEATS THE PURPOSE

Project Team

Architect

SODA Studio

Structural engineer

WB Engineers

Main contractor

Hebs Group