• Client: Private
• Architect: Marek Wojciechowski Architects
• Completion: 2023
• Value: £1.7m
• Expertise: Structures, Building Services

The extension and refurbishment of a two-storey, semi-detached Victorian house in St John’s Wood, North West London. Due to a live rail tunnel located underneath the back garden, careful and close collaboration with Network Rail was maintained throughout to deliver structural and building services solutions with minimal impact to its operation.

The new three-storey timber and brick extension to the rear of the property required a new ground bearing slab dowelled into the existing and new timber joists to be hung from existing masonry. A new cantilevering bridge structure is supported from the new rear wall to give access to the garden, an alternative solution to bearing into the ground, which was not feasible due the Network Rail tunnel underneath the garden. Internal modifications included a small section of retaining wall, replacement of some internal floors and internal modifications to create new openings to the existing building.

The services have been completely redesigned to incorporate a new underfloor heating system throughout. Cooling has been installed to the first floor sleeping areas via fan coil units at roof level served by slotted grilles within the ceiling. The client brief outlined a need for large hot water consumption, fulfilled by two large horizontal cylinders within the roof space along with a cold-water booster tank to resolve poor water pressure. An upgraded gas boiler provides heat to the heating and hot system.