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When Boris Johnson instructed developers to “Build. To build. To build!’ on Britain’s larger brownfield sites, such as former industrial areas, he had in mind to conserve valuable green spaces while increasing the housing stock.
But top-down control has also sparked an explosion in “infill” homes — quirky little properties squeezed into the nooks and crannies of cities.
They’ve popped up among other houses, where garages once stood, or on underused hinterlands on the edge of housing claws.
So if an architect accidentally becomes the owner of a strange piece of land in a break in a row of houses, what does he do with it?
Filler: Triangle House in Kentish Town has a substantial floor space of 117 sq. m. The construction cost was just under £300,000
In Sandy Rendel’s case, he built Slot House, which is almost exactly the length and width of a London Underground carriage.
Two storeys high and just 2.8m wide, the house in Peckham, South London, was completed in 2020 and shortlisted for the Royal Institution of British Architects Grand Designs award for house of the year 2021.
The project was a distraction from what he and his wife, Sally, also architect, were planning to do: plant a garden and possibly expand their home.
“We bought a piece of land at the back of our property because our house had no yard, and this narrow strip was part of that parcel,” says Sandy.
“Originally we had thought to extend our house sideways into it, but it came with planning permission to build a three-storey house, so the value was too high to justify that.”
But there was a problem with the building permit: it was too generous.
“The permission was for a three-story, three-bedroom house, which was a massive overdevelopment. Instead, we designed a one-bedroom house with a separate study area on a mezzanine. That was the right size to make something functional and delightful.”
While they still live in their neighboring family home and rent out Slot House, they’ve stayed in the skinny steel-framed house from time to time.
Insertion: The plot of Peckham’s Slot House cost £75,000 and construction was approximately £220,000. A ‘normal’ property of a similar size in the same location would cost double
‘It’s nice living. It is compact but feels quite generous, it is light and airy. We’ve put a lot of thought into maximizing that space,” says Sandy.
He expects fill-in houses to become commonplace in the future.
Every municipality has a legal obligation to meet its housing demand. If enough small individual plots are used, that is a contribution.
Historically, they weren’t worth it to developers because they didn’t have enough margin or because they’re too hard; but homebuilders seize these opportunities because they don’t need the same margins.’
In fact there are two other infill projects built in the same way.
And the finances are piling up: Slot House’s plot cost £75,000 and construction came in at around £220,000. A ‘normal’ property of a similar size in the same location would cost double to buy.
‘I came away with a lot more gray hair’
It is not just in London that these projects take place. When clients of architecture firm Mackenzie Wheeler said they had an unused yard at the back of their landmark home in Deal, Kent, lead architect Sancho Araujo knew it was an exciting prospect, but it wouldn’t be easy.
“It was quite a challenge as it involved a listed building in a protected area that also fell into the highest category of flood risk,” he says.
‘Just getting a building permit took two years and I came home with a lot more gray hair. We started in 2017 and only finished last year.’
The new house has two floors, has two bedrooms and is spread over 125m².
The recently retired clients have since moved in from their original ownership.
Exposed brick, beams and steel beams on the inside give a semi-industrial look. Total cost including building and construction costs was £550,000
“It turned out pretty well — it’s so different from anything else that happens on that road, and the customers are happy, that’s the most important thing,” says Sancho.
Another recent project is Triangle House, designed by Chris Gilligan at the architectural firm Child Graddon Lewis.
Built in 2020 on the site of a Victorian factory in Kentish Town, north London, which was once Europe’s largest manufacturer of false teeth, the three-storey, three-bedroom house follows a triangular footprint in a bold and entertaining way.
“It was great working on that project,” Chris says. “I think it was the challenges of a rather clunky plot that led to the best aspects of the plan – the different levels gave us a nice little roof terrace, for example.”
Internally, Triangle House has a significant floor area of 117 m². The construction cost was just under £300,000.
The client, Jon Keysell, a partner in Beechwood Properties, says the development was an opportunity to do something unique. “We saw Triangle House as an opportunity to create a beautiful new home, no matter how challenging the site footprint was,” he says.