Artefact adds a series of Caribbean-inspired living spaces to Surrey house

Tell us about the background to the project 

Triangle House is a detached home at the end of a cul-de-sac overlooking Roseberry Park in Epsom, developed by Ideal Homes in the 1950s. We created a new wing that chases the afternoon sun at the back of the garden.

The project, designed for a couple approaching their retirement, aimed to create a welcoming home where their extended family and friends could come together. The clients’ brief was to create expanded living spaces, a new family bathroom, a future-proofed adaptable bedroom, an office-cum-music room, a snug and a reconfigured garden. They were particularly keen to avoid open-plan kitchen and living spaces. As a response, we created a series of spaces that feel distinct yet connected, with openings that frame views from one space to the next. These living spaces spill onto a large terrace for entertaining in the sunset, which the client has nicknamed ‘Club Tropicana’.

Crafted from triangular blue blocks and terracotta tiles, with a warm yellow ceiling, the extension references the tones of the existing house and the client’s heritage, inspired by the book Caribbean Style. The vibrant architecture is framed by an exotic planting scheme by Phenomena, as banana palms and lush planting unfurl along the sweeping blue terrace that unites the existing house and the extension.

What constraints influenced the design?

Working within a suburban context and renovating a post-war house was an interesting challenge that significantly influenced the way we designed the exterior. We wanted to create a street facade in keeping with the streetscape while incorporating a distinctive element – the triangular column and canopy – which sparks curiosity and references a detail on a nearby mid-century apartment block.

The restricted budget meant we adopted a lean material strategy, reducing the volume of material by omitting internal doors and linings and adopting a breathable wall build-up. This approach not only helped reduce costs and carbon but also contributed to shaping the space’s character.

How is the exterior treated?

The external walls are rendered, in keeping with many of the suburban extensions in Epsom.

In contrast, the facade of the extension facing the garden has a more civic character with rhythmic triangular blue piers capturing the daylight as the sun travels round the site. At high level, warm terracotta tiles reference the distinctive arrowhead clay tiles of the existing house.

And how are the new interior spaces used?

The interior was designed as an enfilade of spaces with no doors, resulting in a series of free-flowing yet distinct spaces. A curved double-height entrance hall leads into a small cloakroom, a kitchen, a generous dining room and an intimate snug. Extending along the whole depth of the garden, the interior spaces have lots of daylight and lovely views out to the garden and the trees of Rosebery Park beyond. 

Internal finishes have been left exposed, from the softwood timber joists to the OSB sheathing and the blockwork walls. Pared-back tones are complemented by the brightly painted yellow ceiling and the external blue piers.

What was your approach to sustainability?

A key ambition was to reduce the number and volume of materials, resulting in a lean yet robust building with a distinctive material character. The extension was constructed from a 140mm single leaf of hollow blockwork, sourced from the UK, with mineral wool insulation and render to the outside.

The internal walls act as ‘piers’ to allow the walls to remain thin while defining the spaces. This strategy reduces the volume of masonry required by over 50 per cent, brings down the embodied carbon, reduces the transport associated with two suppliers, simplifies the construction, lowers the cost and thins the wall by 90mm, allowing us to build less to achieve the same area.

What was the main challenge of the project?

Most clients nowadays are keen to build sustainably, but when the budget is limited, sustainable features are often ‘valued engineered’ or omitted by contractors who are not prepared to adapt their working methods. At Triangle House, reducing carbon was integral to the design and we were able to demonstrate to the client that a lean material strategy was actually the cheaper option. This ensured that the main sustainable strategy was not watered down once the tenders came back from the contractors.

Do you have a favourite detail?

Throughout the extension, there is a recurring triangle motif which references the shape of the site and the patterns of the house’s original wallpaper. On the front elevation, the entrance canopy is supported on a brightly painted triangular post. On the rear elevation, triangular piers animate the facade, creating rhythm and depth. The piers were fabricated on site by the contractor using off-the-shelf blocks cut to size. This approach reflects our wider attitude to using low-cost materials in interesting ways to generate character. The contractor was particularly skilled and did an excellent job.

Could lessons from this project be applied elsewhere?

This was the first time we used a breathable build-up in one of our projects and we have been pleasantly surprised by the benefits in terms of cost and ease of buildability. We used blockwork as the main structural inner leaf, which kept the construction simple and was happily embraced by the contractor. In our other projects, we are continuing to explore alternative breathable and monolithic wall build-ups with regenerative materials to further reduce the environmental impact of our work.

Benedetta Rogers is a co-founder of Artefact 

Find more house extensions and renovations

Key data:
Total contract cost £255,000
Area of extension 66m²
Cost per m² £3,500