The London studio that 6a Architects has built for artist and photographer Juergen Teller is almost entirely devoid of colour. But in texture, form and finish, it is as rich as an old master, writes Tony Whitehead
Even by the standards of Concrete Quarterly, the new building on Latimer Road, London W10, is a very concrete building indeed. Admittedly the windows are made from timber and glass, and there are a few brass handrails. But that is about it. The rest: the structure, interior walls, floors, ceilings, soffits, stairs, roof and even gardens are all exposed concrete.
So you might expect the building to lack contrast, feel a bit boring or even oppressive – in fact, the new studio for fashion photographer Juergen Teller is a highly textured, bright, almost playful space, and a superb advertisement for what concrete can do in the hands of imaginative designers.
Sandwiched between a brick-built housing terrace and a modern block of flats, the studio fills a 60m-deep site with a frontage just 7.5m wide. It was this very restricted site that first informed the decision to use concrete. “With contrasting architecture either side, the question was how to graft a new building into this site,” says Carlos Sanchez of London-based 6a Architects. “Concrete provided the solution because, being a material that flows, it can take whatever form you want.”
In practice this meant that the board-marked in-situ concrete that forms the studio’s three-storey frontage has been designed from the start to fit with the brickwork to its left. “We had the boards made to size to ensure they were the same dimensions as the bricks and mortar,” says Sanchez, adding that, in places, this enabled brick and concrete facades to be physically joined together with a consistent horizontal aesthetic. Behind the front facade is the first of three buildings, which contains offices. Moving deeper into the site, this is connected by a garden to the main studio – a largely open space dominated by two slender staircases rising to storage rooms that appear to hang from the ceiling. This in turn leads via another garden to the third building, which houses meeting rooms, offices and a library.
With the exception of the staircases, all the in-situ concrete above ground is self-compacting. While this presented a challenge to the contractor, which had not worked with the material before, it also had a number of benefits, as Sanchez explains. “We chose self-compacting concrete because there was a high level of complexity in some of the pours – especially in the concrete canopies that house the roller shutters to the doors and windows.”
These contain a lot of congested reinforcement, which would have made it difficult to eliminate air by the normal use of vibrating pokers, he adds, and the formwork also had top shutters under which it would have been easy for air to become trapped. “Self-compacting concrete flows more easily around the reinforcement and so reduces the risk of air bubbles without the need for pokers.”
As well as the canopies, other forms presented similar difficulties. These included the sequences of roof beams – spars or ribs just 100mm wide and spaced at 1m intervals below saw-tooth rooflights. Again, reinforcement was too congested to allow the use of pokers, and the sloping saw-tooth forms, like the canopies, also featured top shutters. Self-compacting concrete proved a highly successful solution, flowing into every corner of the forms and producing a finish that exceeded expectations.
Though self-compacting concrete is a more expensive form of concrete, Sanchez says it delivered cost savings in other areas. “Not having to use pokers does save time on site and reduces risk. In the end I’d say it proved a cost-neutral decision.”
Inside, it is the walls that catch the eye. These are constructed from white through-coloured fair-faced concrete blocks, 140mm x 225mm x 440mm. “We used lime mortar with these blocks so even in walls up to 12m long there is no need for expansion joints,” says Sanchez. “The result is a very beautiful finish, but it took some careful sequencing of work to keep them looking pristine.”
The blockwork walls are load-bearing, supporting the in-situ beams and slabs that span the 7.5m width of the site and support the upper floors. “But we needed to keep the blockwork clean and protected from the pours for the slabs. To do this we used the fact that there are actually walls of grey concrete blocks behind the white ones. These were built first and the forms for the slabs were supported off them together with supplementary props.”
Once the slabs had dried, the white blockwork was built up to the slab to provide more support, allowing the temporary props to be removed. But would it not have been easier to simply coat the blocks after the pours? “The through-coloured white blocks have an integrity – a special appearance,” Sanchez says. “None of the concrete is coloured or painted and it was important to us to preserve that look. In any case, not painting saves time.”
Unlike the exterior, the shuttering for the interior in-situ concrete was made from standard-sized, paper-lined MDO boards. “This gives us the matt, non-shiny finish which we wanted as the interior was already quite busy with the blockwork,” says Sanchez. The finish is particularly attractive on the vertical faces, such as those on the store rooms’ lateral walls above the studio, where the more liquid nature of the self-compacting concrete has created faint tide lines. “The layering gives you an idea about how it has been poured, and like the rest of the in-situ concrete we have left it just as it was struck.”
Making the stairs dance
The central studio building is for the most part double-height, and clear from floor to the saw-tooth roof lights. But at each end it features two straight, slim concrete staircases rising in opposite directions to upper-level store rooms.
The design and construction of the stairs is key to both the structure and aesthetics of this area – described by Will York, structural engineer with Price & Myers, as the project’s “signature space”.
“The stairs are the only part of superstructure not done in self-compacting concrete,” he says. “In-situ concrete stairs are usually made with the shutter open on each tread, which are trowelled to ensure a flat finish. Self-compacting cannot be trowelled so we used ordinary structural concrete.”
Being just 600mm wide, with a 150mm-thick waist, the stairs are very slender – they needed to fit with the architect’s vision of a “transparent” centre to the building, allowing occupants to see through from one end to the other. “This made the design of the reinforcement quite tricky,” says York, “particularly as the stairs do more than support themselves. They actually play a vital role in supporting the building at this point.”
The structural challenge stems from the central building’s very open, glazed ends, which do little to stabilise the structure. “At one point, we considered a reinforced portal frame at the ends, but it would have interfered with the desire for transparency in this part of the building. The solution was to use the two stairs as push-pull props.”
The stairs, then, are heavily reinforced with careful connection detailing top and bottom. Temporary diagonal props stabilised the supporting walls until the stairs cured and reached sufficient strength to do the job themselves. “I once read that elegance is something that is working much harder than it appears to be – like a swan or a dancer,” says York. “I like to think that, with these stairs, we have achieved something elegant.”
The patterns made by the self-compacting concrete and the tile-like white blockwork are illuminated by the windows in the saw-tooth roof, the light filtered through the 100mm concrete ribs of the roof beams. The ribs provide a spatial rhythm running the length of all three buildings, ensuring a both a practical and aesthetically consistent distribution of natural light.
With so much exposed concrete, the building, almost incidentally, benefits from having a large exposed thermal mass, able to keep the building cool in summer, while retaining heat in winter. “We have not gone for an environmental rating, but the windows are triple-glazed, it is very airtight, and with the thermal mass effect you could almost heat it with candles.”
Treating the timber
The frontage to Juergen Teller’s studio features a particularly fine and consistent board-marked finish – the result of a technique that involved pre-treating the timber before the shuttering was built. “It is a method more seen in Europe – particularly Switzerland – than the UK,” says 6a’s Carlos Sanchez. “The boards are laid out on the ground and painted with a wet cement wash which is then allowed to dry. This semi-fills the pores of the wood. When dry, any excess cement is brushed off, and release agents applied.”
The effect is similar, explains Sanchez, to using timber that has already been used for one pour. “Because of this there is much less difference in appearance between new boards and reused boards. It ensures consistency.”
It also evens out differences in porosity between individual boards – again helping to deliver all-important uniformity. “We used Douglas fir timber which has a nice raised grain, and this, in conjunction with pre-treating and the use of self-compacting concrete, meant that the grain has been very consistently and effectively transferred to the concrete.”
Prior to the construction, sample panels featuring different mixes, formwork and release agents were poured to fine-tune the technique. “This did highlight one important problem,” says Sanchez. “We realised that unplaned board edges were not giving us a tight enough fit, and we were suffering grout loss between the boards, which was spoiling the look. The problem was solved quite simply by asking the mill to plane the edges.”
The two gardens that separate the buildings also feature concrete. Some of this is the remains of the frame from the building that was demolished to create the site. The effect is of an ancient ruin, only the bones of which are left. On the ground, a thin layer of concrete has been poured and then smashed, allowing plants to seed in the cracks. Maintaining the concrete theme in the gardens helps to unite the interior and exterior spaces, and reinforces the transparent and connected feel that 6a has been at pains to achieve.
Juergen Teller, a photographer who famously prefers to shoot in the real world, as opposed to a studio, is apparently pleased with the results. “For him a studio is more a place to plan – and he never really intended to use this building as a location. But now,” adds Sanchez with satisfaction, “now he does.”
Architect 6a Architects
Structural engineer Price & Myers
Landscape architect Dan Pearson Studio
Main contractor Harris Calnan
Concrete supplier London Concrete
Blockwork supplier Acheson & Glover
Photos: Johan Dehlin; David Grandorge