Adding a roof extension: minimalist mews house transformed by a new zinc-clad level soon copied by neighbours

When architect Graham West and his partner Hana Ichikawa added a roof extension to their two- storey mews house in Stoke Newington last year, their practical needs perfectly aligned with their shared taste for minimalism.

Largely designed by Graham’s practice, West Architecture, the extension, which increased the floor plan by 270sq ft, provided extra space and reduced clutter significantly.

“Hana, myself and our dog Jessie were outgrowing our space,” explains Graham.

“Whenever my parents stayed or Hana’s family visited from Japan, we had to put them up in the tiny second bedroom. The house felt very crowded.”

VIDEO: inside the Stoke Newington house after its sleek upgrade

The couple bought their house in 1997, part of a meandering modern mews development with a serene atmosphere.

On the ground floor, the living room has an indoors-meets-outdoors feel, thanks to its airy, white-walled living room and patio.

This is easily accessible via glass doors that also let daylight pour in. An established crab apple tree at the far end of the patio provides some privacy, while the couple added symmetrical raised flowerbeds.

In the living room, signs of Graham and Hana’s preference for the minimal and coolly monochrome include an extensive grey shelving unit for books and magazines and simple Danish mid-century furniture, namely Arne Jacobsen dining chairs and Verner Panton’s lightweight, slimline Bachelor chair and footstool.

The kitchen is tucked behind the living room but can be easily entered via doors in the hallway and living room.

But it’s the extension, incorporating a staircase, bedroom and bathroom, that truly satisfies a love of the sleek and minimal for Graham and also for Hana, who has her own company, Atelier HI. The inner layer is made of a relatively lightweight timber frame with a plywood skin. Joists from the original roof were reused to form the new one.

The extension’s exterior, clad in “utilitarian” zinc, as Graham puts it, slopes at the same angle as the house’s roofline and is set back slightly from the front of the building. All in all, it’s very discreet when seen from the street.

The couple pooled their skills when it came to the interior. Hana designed the bathroom, while the bedroom, which Graham fondly dubs the “wooden box”, is mostly lined in Douglas fir plywood, flooring included, with all joinery carried out by Barnaby Reynolds.

Thanks to its pronounced woodgrain, which has a naturally decorative quality, the room doesn’t feel austere. The wooden wall incorporates two panels that double as window shutters and if these are left ajar, the gaps between them and the window frame glow when it’s sunny outside.

“The wood really envelops you,” says Graham. “It even smells of timber and has a sensuous quality that makes the room especially cosy in winter. Barnaby showed us various options for wood tones and we opted for a white-oil finish.”

There are concealed Ikea wardrobes behind one wall. A shelf behind the bed provides more storage space, with electric sockets fitted under it so that plugs and cables can be hidden.

An adjoining corridor leads to a similarly monochrome bathroom with a space-saving sliding door. The shower area and vanity unit are lined with pale grey terrazzo tiles subtly speckled with charcoal grey flecks.

“Terrazzo was invented in the 15th century in Venice. It’s one of the earliest forms of upcycling — it’s decorative and durable,” says Hana, proudly. “This version comes in big sheets so it’s relatively easy to install.”

Black taps and shower fittings give the room a sharp, graphic look, while a skylight and window provide ventilation. With the loo in a separate room, the couple often use the bathroom at the same time.

“While Graham is showering, I can do my make-up in the mirror as there’s heating behind it which prevents it from steaming up,” says Hana.

It took time for the couple to achieve their dream of adding this extra floor, even though it is inconspicuous from the outside.

“We applied for planning permission twice and were turned down,” recalls Graham. “The first objection was about neighbours being overlooked, the second was about the extension’s appearance.

“The local council said it would look out of place as no other house in the mews had extensions, although it later helped that we decided to clad the street-facing part of it with mirror-polished stainless steel, which reflects the sky and so seems to disappear. We submitted our application for appeal with the national Planning Inspectorate in Bristol. Fortunately, they felt the objections weren’t relevant and that the extension was in keeping with the development’s architectural style.”

Its pared-down look reflects the philosophy of Graham’s practice: “Most architects are more concerned about how their buildings look from the outside. I’m the reverse of that. What was important for us was the interior and how we live in it.”

Building the additional storey allowed the couple to “reshuffle other parts of the house”, adds Graham. “It has liberated lots of space.”

Building work disrupts everything and they moved out for five months. Once the extension had been built, the smaller bedroom on the first floor was converted into a TV room, complete with an inviting sofa by Danish company Hay, while the couple’s former bedroom is now a guest room.

The first floor, with its shower room, provides guests with a relatively private area. Hana and Graham took advantage of the work done to make other changes. They installed underfloor heating in the living room and got rid of the radiators.

They weren’t keen on the yellowish tone of the original laminate wood floors and replaced them with wood flooring with a paler putty-coloured finish. The washing machine was also moved from the kitchen to the first floor. “It made sense to move it near the bedroom,” says Graham.

They have set a trend in their mews. An immediate neighbour, another architect, took inspiration from them.

“While we were building our extension, he spoke to us about doing the same thing at his place,” says Graham. “We sold him drawings of the project and he recreated it using the same external materials and contractors. And he didn’t have to go through a long planning appeal process since ours had set a precedent.”

In this case, imitation really was the sincerest form of flattery.