Commercial · Full Refurbishment & Roof Extension
A vacant two-storey late-nineteenth-century mews building in the Camden Town Conservation Area, refurbished and extended upwards to become the headquarters of a growing pension trust company. The building is mid-terrace between two houses and sits directly above the Northern Line, which makes the scheme as much an acoustic and party-wall problem as an architectural one: a new second floor inside a flat-top mansard, a ground floor isolated from the structural slab, and every external and party wall decoupled from its neighbours.
A late-nineteenth-century mews building in Camden Town: two storeys, vacant, and smaller than the company that wanted it. The client, a growing pension trust business, needed it to become their headquarters, which meant finding more floor area than the building had.
The site is in the Camden Town Conservation Area. More floor area in a mews terrace means going up, and going up in a conservation area means the addition has to look like it was always going to be there.
The building is mid-terraced, flanked by residential properties at No. 9 and No. 11. Every stage needed party wall coordination, and the acoustic standard that applies is the one you use next to people’s homes, not the one you use between offices.
The building sits over a working Underground line, which puts structure-borne vibration and low-frequency noise into the slab. It is not a problem conventional insulation solves; the energy arrives through the structure rather than through the air.
The mews location limits access, and the fire strategy had to work with a single protected stair serving every floor. In a building this narrow there is no second route to design in.
Consent came with conditions attached to materials, overlooking, noise and renewable energy — four separate things to satisfy before anything could be built.
The new floor sits within a flat-top mansard roof, aligned with the three-storey building next door at No. 9. The dormers are painted hardwood matching the existing style, set behind a raised parapet in yellow London stock brick, so the extension reads as the terrace having grown rather than as something landed on the roof.
Ground and first floor were reconfigured into a sequence of open-plan offices, meeting rooms, a reception and ancillary space, with new rear windows and rooflights bringing daylight and natural ventilation into a plan that had little of either.
This is the part the building succeeds or fails on. The ground floor sits on a proprietary acoustic cradle and batten floating floor system, isolating it from the structural slab and from the low-frequency vibration coming up from the Tube. The external and party walls are decoupled with independent metal stud linings and acoustic mineral wool, which does two jobs at once: it keeps the trains out of the offices, and it keeps the offices out of the neighbours’ houses.
A heat pump system serving vertical ducted fan coil units, with mechanical ventilation and heat recovery to the office areas. The roof-mounted condensers sit in acoustic enclosures to meet Camden’s plant noise criteria — in a mews, where the neighbours’ windows face your roof, plant noise is a planning matter as much as a comfort one.
Eleven photovoltaic panels on the flat roof contribute on-site generation. The windows are triple-glazed at a g-value of 0.4 or lower and work with internal blinds to control solar gain, satisfying Approved Document O on overheating — a real constraint in a building whose new top floor sits under a south-facing roof.
Protected lobbies at ground and first floor, a Category L2 detection and alarm system, and an automatic opening vent at the head of the stair, so that the single stair can serve the whole building safely.
Consent in a conservation area for a vertical extension inserted between two homes, on a site above a working Underground line, with a single stair and a plant strategy that has to stay quiet enough for the neighbours. A vacant two-storey mews building becomes a three-storey headquarters without the terrace losing its character.
The images on this page are design visualisations. The project is at detailed design and building control stage.