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 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.

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 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 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.”

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 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 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.”

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.

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.

“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.”

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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