Architecture studio DHaus has completed the dramatic extension to Datum House, a Victorian maisonette in north London’s Dartmouth Park Conservation Area. The use of full-width skylight floods the lower ground floor with daylight, transforming the space into an openness rarely achieved in subterranean areas.

The existing house, which previously had presented a kitchen to the front and had a rather gloomy living space and bathroom to the rear, has been opened up and extended to become the imaginatively designed space that you see here today. The design introduces an additional bedroom, while also reorganizing the rear of the property to include a spacious living, dining, and kitchen area. This new extension is illuminated by large windows that overlook the garden and the expansive skylight that runs the entire width of the rear facade.

“We wanted to bring light deep into the house and create an openness that feels uncharacteristic of lower-ground-floor spaces,” explained Daniel Wolfson, co-founder of DHaus. The full-width skylight achieves this by visually separating the rear facade from the interior, offering an optical illusion of being outdoors. The studio also used concrete and oak paneling to create a continuous datum around the space, which flows into a slightly sunken walled garden, stepping up to a garden studio at the far end.

The front section of the home has been repurposed to add an additional bedroom and bathroom, while the upper ground floor, containing the main bedroom, remains unchanged. Due to the building’s location within a conservation area, the exterior of the extension was required to blend with neighboring structures. DHaus opted for pale vertical brickwork, arranged in a stack bond pattern to subtly distinguish the new addition.

The interior finishes are a minimalist blend of earthy plaster and oak, contributing to a warm and cohesive atmosphere. The rear facade’s monolithic brickwork, with deep reveals, also conceals practical elements such as sliding doors and curtain tracks, further emphasizing the integration of form and function in this thoughtfully executed design.