Jan Kattein Architects’ ingenious roofs add height but little weight to turn derelict garages attracting antisocial behaviour into lively spaces for community use in north London
While Angel Edmonton might sound divine, the reality was less heavenly until recently. By day, Fore St, running south from Edmonton station, is a bustling commercial centre, but at night locals felt decidedly less secure. The Joyce and Snells estates to the west, built in the 1950s-60s, had all the hallmarks of deprivation; low income, no perceived access to training and employment, and poor access to high quality environments and green spaces. Little surprise then, that when asked by Enfield Council last year, residents balloted for the full-scale demolition and regeneration of the estate over the course of the next decade.
With Jan Kattein Architects, the Council was also awarded £2.2 million from the Mayor’s Good Growth Fund to implement a number of small but significant interventions on Fore St and roads west to the estate. With a bold corrugated barrel vault and butterfly roofs, the most notable of these is JKA’s £1.4 million Angel Yard. Set in the heart of the estate, 35 derelict garages and forecourts that were until recently a hotspot for illicit activity, have been reinvented as a start-up hub, helping address the dearth of skills training and employment opportunity. Looking like a new-build, Angel Yard is for the most part a radical refurbishment of the garages for charity LaunchIt, which provides workspace at below market rates – and business support – to local young people. Running between the garage-sized units are two covered shared spaces. One links a primary school and JKA’s new ‘School Street’ in front with a community centre to the south, enlivening the estate by creating routes you’d want to walk down.
For JKA director of projects Gabriel Warshafsky, the challenge was to bring in the building, which has a meanwhile use of up to just 10 years, to a tight budget while keeping embodied carbon to a minimum. ‘As much as being an investment in realising social impact, we tried to retain as much of the building fabric as we could, adding as little as possible,’ he explains, ‘but roofs had to go anyway due to the asbestos they contained.’ But, Warshafsky adds, as each 2.4m wide garage was separated by only a 70mm blockwork wall without foundations, there was no way for these retained walls to take extra imposed loads. This generated the distinctive form. ‘One of the challenges was the low head height – something we couldn’t resolve by building up the walls’, he continues, ‘and as we had the idea of using a roof treatment to differentiate individual units, we realised barrel vaults could create generous volumes without significant added weight.’
The solution was to create double timber beams above the blockwork walls which are supported on timber posts sitting on discrete pad foundations in front of the existing garage walls. From these spring four curved beams spanning the 2.4m between walls, made of three layers of bonded 18mm ply with 150mm by 50mm joists running between them. With a final finish of corrugated galvanised steel sheeting bent against its sectional profile rather than with it, Warshafsky reveals they’d had a ‘pipe dream’ of using its intrinsic strength structurally, but that the amount of roof insulation required had precluded it. This came from the decision to not break out floor slabs to install insulation there, which would have generated concrete waste and had knock-on effects on threshold heights and thus unit accessibility.
‘Instead, we installed a minimum of 32mm rigid floor insulation below a simple, 18mm ply floor finish – enough to counter the thermal bridging – and concentrated on bulking out the roof with Rockwool to achieve overall Part L compliance, which had the effect of increasing roof loadings,’ he explains.
Timber beams above the separating walls not only deal with the very rough tolerances of the blockwork walls (surfaces have been left unfinished, unlined and unattenuated – graffiti and all – for tenants to treat as they will) but also form the base of a galvanised steel valley gutter detail, which directs rainwater to drainage runs at the front of units. In a charming detail, these dispense into barrel planters, which then drain to a central outlet in the covered street.
Creating the double height communal area, and a kitchen and WCs to the south, involved merging four garages and adding new timber beams to augment the existing walls to take the new roof loads. Here large windows now create an active frontage to the street and community centre opposite. The beams allowed the contractor to build the walls up in timber and run joists from wall to wall to form the larger curved roofs. As with the soffits in both the single and stair-accessed two-storey units, they are lined in 4mm bent ply to give a clean, warm finish. That warmth is reflected too in the choice of timber joinery by Rationel for windows and doors, which gives due thought to reducing the embodied carbon. With water supply and sewerage along the north side of the common area, capped off supply and drainage runs in the workspace blocks behind it handily allow units to connect to them if needed.
This being JKA, the concept of shared space is fundamental, so clear polycarbonate external canopies covering the shared forecourts between facing workspace blocks were in effect poster-boys for that idea, as a communal spill-out and outdoor events space. Warshafsky accounts for how the firm settled on the butterfly roof form: ‘The wing structure was partly about getting the top of the roof over the barrel vaults’ peaks without making the whole thing ludicrously tall, but it was also an exuberant shape that we felt was suitable when trying to set a new tone for the area.’ There had been an idea of making the workspace roofs demountable but cost precluded this, so, he adds, they concentrated on the canopies, where timber elements are bolted together rather than screwed. The architect is keen to credit contractor Sullivan Brothers for its efforts here, calling them ‘skilled craftspeople’. He quips that they were at times bemused by the basic level of finish but they also realised ‘it wasn’t just about putting in standardised products, but ingenious carpentry too’. It was perhaps the latter that contributed to the £2,333/m² cost.
The workspace opened in the summer and is bedding in nicely. On school days, the route from the JKA’s new ‘School Street’ just to the north becomes a thoroughfare for mums and kids, and 70% of units are now let to the likes of architect Fisher Cheng – who worked with JKA on the local street art project – an accountant, nail bar, bubble tea shop and brother and sister roti stall. Notably, they were generally keeping their front doors open, not just on hot days but, with the butterfly-roof canopies between them, on rainy ones too. And with invasive, estate-wide regeneration about to begin, it feels like this meanwhile use may yet be of real import to the wider community.