Large curved opening distinguishes extension to listed Victorian house

Can you describe the project?

The project involved the sensitive renovation and extension of a Grade II listed 1850 house, part of a fine Victorian square in south London, for a private client.

The rear extension features a large curved opening and uses custom-made segmental bricks, which were designed by the practice and draw on arches in the original architecture. The bricks’ motif is playful and contemporary, yet uses the traditional Flemish bond visible on the existing house.

Were there any significant factors that influenced the design?

The house’s listed status affected the height of the rear extension and the levels of intervention throughout the project.

The main changes to the house were at lower ground floor, which was relatively plain in terms of existing architectural detail. Cellular rooms were interconnected and opened out to the garden through the new extension.

Generally, a lighter touch was employed for the upper floors, respecting and restoring the existing historic detail of the listed building.

How did you treat the exterior?

The front of the house, which faces towards the formal square, features ornate stucco dressings but the five-storey rear elevation is plain red brick. The neighbour’s outrigger to the right also creates a tall enclosing wall in dark brick. We wanted to add a further extension which would work with this pared-back, brick context.

The combination of brick context and arched openings led to the idea of using a bespoke brick with an arched/ segment pattern to give the extension a subtle richness of detail.

How did you design the interior?

The clients had expressed their love of Scandinavian modernism, particularly its use of timber panelling. We paid close attention to Gunnar Asplund’s 1936 Gothenburg City Hall.

The house’s panelling is made of Douglas fir plywood arranged in two bands: a solid upper panel and a slatted dado layer. It is installed with incredible craft and attention to detail throughout the lower ground. Joints are perfectly chamfered and secret doors conceal a hidden pantry and a TV cupboard. A special arched opening at skirting level allows the owners’ cats to access their hidden food bowls, an echo of the primary arched glazing in the rear extension.

What was your approach to sustainability?

The existing house is listed and is located in a conservation area. Consequently, a key requirement was to retain as much of the existing historic fabric as possible: single-glazed timber sash windows, cornices, skirtings, architraves, joists and floorboards etc. In addition to protecting the house’s heritage status, this factor helped to reduce the amount of carbon produced by the works. At the same time, it precluded the possibility of an air-source heat pump and internal wall insulation, which we would normally use.

What was the project’s main challenge?

The main challenge was adding to the listed building in a way that balances a contemporary approach with the historic setting. Our design is sensitive to the context but also playful and inventive.

What is your favourite moment in the project?

There are various moments. The bespoke brickwork of the rear extension adds a large amount, especially when compared with rectangular stock brick. The Douglas fir panelling gives the lower ground floor interior a special feeling of quality. The circular rooflight in the lower ground garden room works very well, framing a view of the tall existing London plane tree in the rear garden. And the cat door, echoing the garden room opening, is a nicely witty moment.

Are there lessons from this project that might be applied elsewhere?

The use of bespoke bricks to add architectural richness and material quality is certainly something we will continue to explore. It’s something that was done a great deal in Victorian architecture but fell out of fashion with the rise of modernism. We think it’s time to bring it back.

Dominic McKenzie is founder of Dominic McKenzie Architects

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Key data:

Total contract cost Private
Area of extension 15m² 
GIFA cost per m² £3,508 (overall project)