In the first of a new series on the diverse collaborators with whom architects work to bring projects to life, Groupwork chairman Amin Taha opens his contacts book
We met Ateliers Romeo when making a helical all-stone staircase for a private house. The convention is to incorporate steel stringers and substructure, bolted to the walls and floor and dressed in stone, but I’d read that engineer Price & Myers had rediscovered how to make ‘part-cantilevered, part-reciprocal’ stone stairs – a method forgotten after the first world war. Each tread rests on another, but is keyed into the wall to stop it twisting; the smaller the overlap the more elegant the stair.
In France stonemasons are still trained in that technique, and the job went to Ateliers Romeo, a French company based in Italy’s stone industry region. While visiting them we saw raw master blocks coming into the yard which looked like they might make columns. They explained that in France and Italy, stone is still used for loadbearing structure, and is cheaper and quicker than using steel or concrete and stone cladding. It used to be called ‘austerity construction’; Fernand Pouillon’s post-war apartments on the Marseilles waterfront cost 10% of what Corb spent at the Unité d’Habitation. Our sustainability consultant later confirmed that a stone structure is also 92% lower in embodied carbon than a stone-clad steel frame.
It was there that we got the inspiration for a number of structural stone projects that have followed, including our office at 15 Clerkenwell Close with another French-trained mason, Pierre Bidaud of The Stonemasonry Company; a 10-storey block with an exoskeleton of lava stone on site in north London, with Ateliers Romeo; and series of private houses with loadbearing single-and double-skin walls of stone and pools using contemporary versions of medieval rib vaults.
Some structural engineers are dogmatic, finding architects’ inputs an irksome diversion from their apparently expedient solutions, often already designed in their minds. Steve is one of those people with whom you can sit and talk at length, reworking ideas until you produce one that neither of you would have come to independently – something cheaper, more efficient and with lower embodied carbon.
One example is an unbuilt competition-winning scheme for an underground transport interchange in Sofia, Bulgaria, where the challenge we threw down was how to make a cheaper station, and if possible, avoid the expected architectural language of steel and glass associated with infrastructure since Hector Guimard’s Paris Metro.
Cut-and-fill stations are made by digging a hole, building tunnel walls and floor, then putting a roof on top. Stopping the walls collapsing in the meantime involves temporary works, which can be 30% of the project cost. It occurred to us that instead we could just pile the ground to make walls, dig down a metre or so and then cast permanent roof beams directly against the earth; permanent temporary works, so to speak. Steve suggested casting the stress diagram of a roof, so it’s deeper in the middle and shallower at the sides, deforming where tunnel becomes larger and smaller in platform areas, and leaving holes through which to drop diggers. It directly informed the architectural language of the station, of cast walls and ceilings textured by the earth, with intermediate ticket office levels built like support structures in the mining industry. Underground entrances and exits became location-specific, signaled as rugged fissures in the ground – the start of a journey into the underworld.
Working with very good artisanal metal-bashers like Phil Benson we have learned a lot about how to reduce the amount of material you need, and how to finish it. He began working on classic cars – if you found half of one in a barn he and his team could fabricate the missing parts – and we’ve often gone to him for specialist metalwork, such as a 3m-long steel plate table on four 40mm legs.
In our self-built office at 15 Clerkenwell Place his team refined the designs of a steel bridge and meeting box, as well as the stair that spirals around a lift cage of mild steel mesh, like a Parisian apartment building. He taught us to avoid, as often as possible, finishing in paint or polyester powder coating, instead gently warming the steel with a flame and rubbing beeswax into the metal to leave it with a durable and natural tone. All steel was treated in that way, except the studio stair which had accumulated all sorts of water marks, dust and abrasions during construction – an atmospheric patina that Phil and I liked enough not to beeswax it, but instead leave it wear with use. Phil is inconveniently retiring to Spain, though he does leave well-trained colleagues.
There is a fundamental advantage to having relationships with specialist suppliers and subcontractors – the people who actually get their hands dirty and therefore understand materials, their cost and how they might best be assembled in context of other building components. Talking to and designing with them well in advance of submitting a planning application avoids ‘value engineering’ as all building components will have been tested and costed, so a main contractor only needs to tender their overheads, prelims and profits.
We’ve known Glasstec Systems for over 10 years. Working with them we’ve learned how to design much cheaper, more simply detailed window, door and curtain walling systems, where possible substituting excess metal and mechanical fixings with structural glues stronger than the glazing units, and certified to last longer.
At our house on Caroline Place, Kensington Gardens, Laurence helped us develop a thermally broken and weather-proofed Miesian cruciform column and beam section. Internal and external doors and windows, and the structure of a conservatory, were fabricated from back-to-back lengths of brass L-sections, with slim nylon blocks sized for thermal isolation glued between, and double-glazing units glued to the outside L-section.
As told to Chris Foges.
Interested in making buildings? Get the inside story in detail on Tonkin Lui’s CLT Water Tower staircase