Architecture studio DHaus has used a full-width skylight to draw light into this extension in north London, which is finished with a pared-back palette of pale brick, plaster and oak.

Named Datum House, the existing Victorian maisonette in the Dartmouth Park Conversation Area has been opened up by DHaus at its lower ground-floor level and expanded with an additional bedroom.

"The design not only addressed the clients' desire to bring light deep into the house but also created a sense of openness that's rarely found in lower ground floor spaces," DHaus co-founder Daniel Woolfson told Dezeen.

Previously, the home's lower ground floor had been organised with a kitchen at the front and a poorly-lit living area and bathroom to the rear.

DHaus has added a rear extension to create space for a spacious living, dining and kitchen area that is illuminated by large windows overlooking the garden and a full-width skylight above.

The skylight creates the effect of separating the rear facade of the home from the interior, expanding the feeling of spaciousness while also giving the "illusion" of being outside, the studio said.

Both concrete and oak panelling form the namesake datum around the base of this space, which extends out into a slightly sunken walled garden. This steps up to a standalone garden studio at the end of the site.

"We tried to separate the facade wall from the main structure with a full-width, wall-to-wall skylight, which created an optical illusion that makes one feel as though you're almost outside looking to the garden," said Woolfson.

"We made the skylight as wide as possible to make sure it was as bright as possible and did not feel like a basement," he added

"We expressed the change in level from the garden level to the sunken courtyard with a continuous datum line that runs around the external courtyard and continues internally onto the joinery of the living room."

The space freed up at the front of the home has been used to create an additional bedroom alongside a bathroom, while the upper ground floor containing the main bedroom has been left unchanged.

Due to the site's position in a conservation area, the exterior of the extension was required to be in keeping with neighbouring buildings. DHaus opted for pale brickwork that is laid vertically in a stack bond to subtly set the new addition apart.

This is married with earthy plaster and oak furnishings throughout the interior.

"The rear facade, with its monolithic stack bonded brickwork, appears as a standalone architectural element, its deep reveals serving a practical purpose of concealing the sliding doors and curtain track," explained Woolfson.

DHaus, formerly known as The DHaus Company, was founded in 2010 by Woolfson with David Ben-Grunberg. Previous residential extensions by the studio include a London extension clad in a variety of differently-shaped wooden shingles and a revamped terraced home featuring a butterfly-roof extension.

The photography is by James Retief.