District's canny, colourful extension wraps around ground floor flat

Who is your Colour Casing project for and what was the brief, including any specific requirements. 

The scheme sought to create the flexibility of a three-bedroom, two reception house within the extended footprint of an original small one-bedroom flat. The purpose was to allow our client to remain within their family home in an area they live, work and love without needing to step up the property ladder to a higher value property that would have been economically unachievable. Spend was key and innovative and unconventional construction techniques consisting of minimal intervention, pad foundations and a timber frame structure resulted in a simple, modest budget and environmentally friendly build solution.

Briefly describe the project, including the existing building it is extending and the work that has been done.

The original dwelling was a dilapidated ground floor flat in need of full refurbishment and extension. The rear and side addition was carefully considered to ensure the spaces are separate, unique to their own setting yet always borrowing from adjacent areas where needed. The works had to be simple in their construction and impact. A minimal dig solution was proposed with only three pad foundations supporting a steel frame perimeter with a timber frame formed above. This effectively formed a loft extension at ground floor level with the works progressing simply, quickly and with less impact on the ground.

Was the planning context/situation important in the design? If so how?

While there were wraparound additions there was limited precedent within the local street scene for such a deep addition to the existing outrigger. The depth was important in order to retain the corner of the existing outrigger and ensure that we limited the structural works and kept control of costs. The retention of the corner also meant that, from a design perspective, we were able to subtly define separate places within the overall room. 

Explain the external treatment. 
As a practice, we strongly encourage the use of readily available and simple materials where possible. In Colour Casing this resulted in the use of treated timber battens for the external cladding to the face of the extension with contrasting planed timber to the wraparound garden fence, producing a contrast between the perimeter treatment and rear elevation. Both were finished in a coloured stain to enhance the subtle contrast and ensure a robust yet highly designed and bespoke finish. 

How have the interiors been designed?

Zoning was achieved through colour blocking, such as the yellow of the kitchen island, while the retained chimney stack and re-used fireplace helped define the dining area. The tall ceiling within the sitting area and the fitted furniture create the impression of space and light within a small footprint. These details help give each space a minimal difference to the next, with other finishes allowing it to subtly appear as one when required. High quality unique materials were used strategically along with larger format features. The windows, mirrors and furniture give the impression of generosity in what would otherwise be considered confined areas, ensuring no space feels compromised.

Tell us about your favourite detail/moment in the project. 

It is hard to pinpoint specific elements because the success of the project lies in the way every part works as a whole. There are a few key viewpoints that bring much joy. The way the overlapping shapes of the existing and new architectural plains within the kitchen slot together is simply and beautifully constructed. The consideration of how light falls within each space creates forms and shadows around the bold colour blocking. And the seated space to the rear reflects out from the large picture window to the garden, creating a warm feeling of calm in the busy city.  

What was the biggest challenge on the project and how did you overcome it?

Budget and finding a progressive contractor. Obtaining a collaborator that would engage with the unconventional structural works for a project of this size was difficult. Most projects of this scale and budget will only be possible with a small builder. As such, knowledge of alternative methods is often limited or simply not desired resulting in cut-and-paste projects of standard cavity construction and output. The client was able to engage with a large commercial scale contractor and understood the efficiencies proposed by the architect and engineer resulting in a controlled budget yet significant output.

What would you do again? What would you not do again? 

The timber frame solution over a limited dig and foundation proposal was key in making the budget stretch so far. It ensured that we could achieve the maximum addition and exploit the existing footprint to its extreme. We are extremely delighted by the scheme and its outcome. The play of scale in the main spaces was achieved by using larger objects and fixtures than you would expect in such a small space. This could have been taken further across the remainder of the dwelling by using larger yet still off-the-shelf door openings to bedrooms and other rooms. 

Alexandra Rees is co-director at District architects.

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Key data

Total contract cost £95,000
Area in m² 90
GIFA cost per m² £1055psm (approx.)