Lett Road, Stratford, London by Proctor and Matthew Architects
With its rampant four-storey cantilever, Proctor and Matthews’ tower overlooking the Olympic Park has made regeneration fun, writes Felix Mara. Photography by Tim Crocker
Proctor and Matthews Architects’ Lett Road apartments, completed in September 2010, might be a bold and uncompromising building, but it also had the full blessing of the planners. The east London borough of Newham’s policy was to encourage intensification of the site, which is just off the main approach road to Stratford. By building to a height of 12 storeys, it has been possible to fit 64 mixed-tenure apartments (including 10 affordable units for the Guinness Trust), and to provide a landmark overlooking the Olympic Park. Thus it combines Newham’s targets to increase densities and to regenerate an area characterised by disused industrial buildings and low-quality housing.
Newham also wanted the development to relate to the immediate streetscape of two- and three-storey buildings, and Proctor and Matthews responded by articulating it as two interlocking elements: one L-shaped, five storeys high and mainly brick-faced; the other rising to 12 storeys and zinc-clad, with a four-storey cantilever. ‘We were excited about the cantilever,’ says Price & Myers associate Tim Wainwright, putting paid to the notion that all structural engineers are intent on sacrificing architecture on the altar of efficiency.
There is no structural rationale for the cantilever. It may reduce vertical loads on the foundations below the south facade, but overturning forces acting on the inboard foundations, generated by the cantilever, dramatically offset this reduction – it would have been much more efficient to transfer loads to the substructure by direct vertical paths. Price & Myers carried out finite element analysis of the cantilever, producing separate models of isolated areas of interest. There was no BIM model, although Price & Myers used Revit software, with data imported from Proctor and Matthews’ MicroStation files to model and remodel the cantilever. ‘When the cantilever was de-propped, there was a ridiculously small amount of settlement – about 3mm,’ says Proctor and Matthews associate Georgina Bignold.
The back-spanning components of the concrete frame, which connect with 300mm-thick core walls, were difficult to co-ordinate with the windows, and the height of the space below the cantilever (plus the wedge of dead space above it) took out two flats. To use a phrase often repeated in the Arup Journal, the cantilever was there ‘for architectural reasons’. It was also there because Newham liked the way it addressed the A118 while leaving the L-shaped block alone to deal with Lett Road and Jupp Road. Developer Thornsett’s initial enthusiasm for the cantilever waned when Price & Myers explained the full implications, but they stuck by Proctor and Matthews’ concept. ‘When contractor Lancsville went into receivership, Thornsett took over and micro-managed the subcontractors,’ explains Proctor and Matthews director Andrew Matthews.
The L-shaped block adapts to the scale of the side streets by juxtaposing a range of finishes and window styles. – some punched into brickwork and others more flush, within areas of composite aluminium sheet cladding and vertical cover plates. Proctor and Matthews originally proposed opaque glass and timber, but only one instance of this survived value engineering. The massing is also animated by balconies and perforated sheet-clad oriels, which required meticulous co-ordination with the structural core. Whereas the balconies have horizontal, thermally broken Schott connections, the oriel windows have simple bolt connections with neoprene joints. ‘To protect children from falling, the top of the guardings are 800mm above the window ledges, and will therefore be at some people’s eye level,’ says Bignold.
Procurement was Design and Build, but Proctor and Matthews produced Stage F design intent drawings that worked through waterproofing, insulation, ventilation and fire safety problems. They were then novated to Lancsville. ‘Thornsett was quite clever,’ says Matthews. ‘They knew that if we only took the drawings to Stage E, the design quality would suffer because there would be too much room for interpretation.’
Layouts follow the guidelines set out in the National Housing Federation’s Standards and Quality in Development: A good practice guide. ‘The scheme also followed ‘Secured by Design’ principles, with a clear definition between public, communal and private realm space, and street-level entrances to the units on Lett Road,’ says Bignold.
The development will benefit from the Greater London Authority’s plans to make landscaping improvements to the adjacent disused Charterhouse river, forming a new linear park connecting to Stratford Station. ‘The GLA was very supportive of our design approach, but felt that what we were doing should inform the surrounding development,’ says Bignold. ‘So they asked us to produce an urban design study for the sites immediately adjacent.’
This is not Proctor and Matthews’ most dainty building, and it isn’t trying to be. There’s a touch of the Stirling and Gowan about it, especially in the geometry of its rampant cantilever. But along with the Brutalist overtones, its rooftop playground and sheltered courtyard bring humanity, and a sense of fun.
Start on site September 2008
Contract duration 24 months
Net internal area of apartments3,488m2
Form of contract Design and Build
Total cost £9.9 million
Cost per square metre £2,255
Architect Proctor and Matthews Architects
Client Thornsett Group
Structural engineer Price & Myers
M&E consultant The Kut Partnership
Quantity surveyor / project manager / CDM co-ordinator MDA Consulting
Approved building inspector Auditec
Main contractor Lancsville Construction
Estimated annual CO2 emissions 0.2 tonnes
Energy efficiency rating B (87)
Environmental impact (CO2) rating A (97)
Annual energy use135kWh/m2
On-site energy generation Biomass communal heating system with Remeha biomass woodchip and pellet boiler operating a lead boiler and Remeha Quinta 115 gas-fired high-efficiency boilers providing back-up during times of high demand
Average u-value for walls 0.23W/m2K
Average u-value for windows1.8W/m2K
Average u-value for ground floor 0.23W/m2K
Airtightness at 50pa 6.6m3/h.m2
Zinc vertical standing seam cladding VM Zinc quartz grey
Zinc interlocking panel cladding VM Zinc pigmento green
Zinc standing seam cladding VM Zinc anthracite
Zinc standing seam horizontal cladding VM Zinc copper green
Aluminium rainscreen cladding Beige and anthracite Alucobond