This Exquisite Extension With a Zigzag Roof Was Made Possible by Neighborly Collaboration

In London, architect Julia Hamson transforms the dark, cramped kitchen of her Victorian terrace house into a flexible gathering space.
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When London architect Julia Hamson founded her studio 4 S Architecture in early 2020, her first project was one close to her heart—a rear extension to the family home she shares with her husband and young daughter. The couple had been living in the home for six years, so they knew exactly what was needed. "The house was very dark, so my main brief was to create a flexible, open-plan space filled with natural light," says Julia. "We wanted our whole family to be able to come together to eat, cook, and play—and the space had to be able to adapt to the changing needs of our family as our daughter grows up." 

The rear extension is clad in Brunel smooth blue brick. "I chose a dark, gloomy color to complement the dark blue iron spot in the London stock brick that the rest of the house is made of," says Julia. "I wanted it to be different and feel like a contemporary addition that speaks of its time." 

The Victorian home is on a friendly cul-de-sac street in South London, and it was during the annual neighborhood street party that Julia got talking to her neighbors about how they were both planning a rear extension. They quickly realized that by working together, they would be less limited by planning regulations when it came to the height of the extension.

The rear extension features a large picture window that allows for a strong connection with the garden without the visual distraction of a folding door frame. The powdery pink concrete resin floor is from Pure Floor. "I wanted a warmer tone than just gray concrete," says Julia. "It works really well with underfloor heating, is seamless so there's no grout to fill with dirt, super easy to clean, and really robust."  

Julia had previously applied for planning permission, but had been asked to reduce the height along the boundary to 2.5 meters rather than the proposed four meters. The neighbor’s architect had designed a sawtooth roof facing the opposite direction, and so it was suggested that they create a four-meter-high party wall at the junction.

The light-filled extension opens out from the narrow hallway that runs through the home from the front door. "I'm from Canada and I worked in Chicago, so I know the work of Frank Lloyd Wright well," says Julia. "One of the interesting theatrical architectural techniques he often used was to design a very low, dark entrance hall so that when you emerge in the main living space, it feels brighter and more dramatic by way of contrast. I already had that dark corridor, and the four-meter-high extension is filled with natural light. I always wanted something magical at the end of the journey." 

The neighbors built their extension first, and Julia and her husband paid for half the party wall. A year later, after the birth of their daughter, they built their extension up against it. "This approach allowed our neighbors to do something fun on their side of the wall, and allowed us to create a dramatic space in our extension," says Julia. "It’s really unexpected when you come in."

The back wall of the original home has been finished with a powder pink plaster. The arched wall lamp was designed by Julia as a refined interpretation of a Parisian street lamp—a playful reference to the fact that the wall used to be an exterior wall. The bespoke lamp was manufactured by Yuval Tzur Design, a company she found on Etsy. 

The home is a typical Victorian terrace house that had been lovingly taken care of by the previous owner, who grew up in the home and lived there his whole life before retiring to the seaside. "There were some lovely period features—decorative plaster corbels with women’s faces, original fireplaces, and even a small gas lamp," says Julia. "I wanted to keep the front of the home as true to the original as possible and for it to become more contemporary as you move further back into the house."

The plaster corbels and the gas lamp are original features of the house. Julia retained the cable up the wall and arched arm of the lamp, and had it re-wired by an electrician. The bulb is an Edison LED globe light. The vintage cast iron radiator is from The Old Bath House in Sydenham, London.

The stair leading from the ground to the first floor features the home’s original bannister. The paint has been stripped back to create textural contrast with the clean finishes in the rest of the home. 

The living room is painted in Dulux Raven Plume. "I saved a bit of money by going with Dulux paint, and put the savings towards more expensive lighting," says Julia. The pendant lamp is a George Nelson Saucer Bubble Pendant Light, which was designed by George Nelson in 1947 and first produced by Herman Miller in 1952.

The central room—previously the dining room—has been opened up to the narrow hallway to let more light into the interior. The space is now used to store bikes, strollers, and coats.

In order to preserve the feeling of the existing home, it was decided that they would keep the original proportions of the front two rooms, but open the second room up to the hallway by the stair to let light into the previously dark and narrow corridor. Likewise, they kept a fairly conventional plan for the first floor, turning a guest bedroom into a home office and converting a large bathroom into a smaller bathroom and a second bedroom for their daughter.

The primary bedroom features an original fireplace and a small desk with a Model 105 Small pendant lamp by Le Klint, a classic designed by Mogens Koch in 1945. Like the stair bannister, the fireplace offers a rich textural contrast to the rest of the sleek interior. 

The primary bedroom is painted in Dulux Woodland Fern 1. The bedside lamp is a Carronade Nordic Spot Pendant by Le Klint. Eventually, the couple plan to add another floor and move the main bedroom upstairs. 

Before the rear renovation was done, the couple completed a number of smaller phases—including converting a very large bathroom on the first floor into a smaller bathroom and a bedroom for their daughter. 

The rear extension—which replaces the tiny, original kitchen—dramatically opens out from the hallway. Julia wanted to ensure that the large, open-plan space had different zones of functionality within it—and the zigzag roof structure plays a key role in defining the space. The voluminous space beneath the pitch of the zigzag creates a "room within a room" for the dining area, while a lowered flat ceiling—above which the first-floor bedroom sits—defines the cooking area of the kitchen. The space beneath the high skylight is a play area for the couple’s young daughter.

The voluminous roof pitch above the dining table defines a "room within a room" in the open-plan space. The pendant lamp above the table is an original glass Holophane lampshade found in Hastings Antique Shop, a salvage antiques shop in Hastings. The wiring has been updated to meet current safety standards, and the yellow cable is from Industville.

A large skylight in the rear extension allows for natural light in the deepest part of the plan. Due to the narrow corridors, the large glass panels had to be craned in during construction.  

The space beneath the skylight is used as a play area by the couple’s young daughter. A soft pink rug helps to define this as a distinct zone in the open-plan space. It will eventually be transformed into a study area for the couple’s daughter. "I've designed a run of joinery that will go along that wall which will have a fold down desk for homework and more storage," says Julia. 

The kitchen sits beneath the lower part of the ceiling, below the first-floor bedroom. Most of the kitchen cabinets are crafted from FSC-certified ash veneer, which has been whitewashed to reduce yellowing. "I chose it for the light color and the subtle grain pattern," says Julia. The white kitchen cabinets on the lower level offer contrast and are a bit more robust and easier to clean. 

"The zigzag roof draws inspiration from the existing angled lines and forms at the back of the house," says Julia. "We had to be 2.5 meters on the boundary at the front of the house and couldn’t go higher than the existing ridge at the other boundary—the zigzag allows more height and volume in the middle of the extension, rather than just connecting the points in a straight line. It gives a bit of extra drama and volume inside."

The solid ash dining table was co-designed by Julia and Etch Woodworks to reflect the design language of the cabinetry. It is set up with four chairs for everyday use. If the family has guests, however, it can be rotated 90 degrees, and can fit six people. The window ledge has been designed to double as a bench seat, so there’s no need for additional chairs.

Inside, Julia used a palette of pared-back, natural materials to create a light and airy environment inspired by her trips to Copenhagen. She initially wanted to use oak or ash hardwood timber for the exposed trusses, but decided to go for a more budget-friendly, standard structural-grade timber. The builder sanded them down to create crisper edges and a more finished appearance, and the savings were spent on the grade-A birch plywood behind the trusses. "That combination elevated what is quite a humble building material into something much more refined and special," she says.

The kitchen countertops and backsplash are made from reconstituted stone—a material chosen for its durability. The pendant lamps above the island are Mini Caravaggio lights by Cecilie Manz for Fritz Hansen. 

The coffee station is located behind foldaway doors, so it can be concealed behind an ash timber panel for a tidier appearance when the couple are entertaining. 

As a result of clever savings, such as the structural-grade timber trusses and a large picture window instead of folding doors, the extension came in just over the original budget of £150,000. Extra features, such as additional joinery, a refurbished front door, and a second floor with the main bedroom, will be completed at a later stage.

The picture window has black-out blinds, and there is a projector installed above the kitchen cabinets, so the wall next to the dining table can be transformed into a 2.4-meter-wide surface for film screenings.

"I feel so fortunate to have had the opportunity to design a home for our family—and to have it completed before lockdown," says Julia. "We spend so much more time in our homes these days, and turning that small, cramped kitchen into a space where we can all be together has completely transformed the way we live in the house." 

Front and rear elevations of Zigzag Roof House by 4 S Architecture

Section through the extension of Zigzag Roof House by 4 S Architecture

Ground floor plan of Zigzag Roof House by 4 S Architecture before the extension. The central room was opened up to the hallway to let more light into the interior in an earlier renovation.

Ground floor plan of Zigzag Roof House by 4 S Architecture after the extension 

First floor plan of Zigzag Roof House by 4 S Architecture before the extension

First floor plan of Zigzag Roof House by 4 S Architecture after the extension

Related Reading: 

A Bold Addition With a Zigzag Roof Ushers Light Into This Melbourne Home

A Dramatic Sawtooth Roof Infuses This Midcentury Florida Revamp With Vintage Vibes

Project Credits:

Architect of Record: 4 S Architecture / @4sarchitecture

Builder: Big Town Construction

Structural Engineer: Heyne Tillett Steel

Lighting Design: 4 S Architecture

Interior Design: 4 S Architecture

Bespoke Joinery (Table): Etch Woodworks

Bespoke Lamp Production (from design by architect Julia Hamson): Yuval Tzur Design 

Photography: Henry Woide  


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