London-based Alma-nac remodelled and extended the Cornwall Mews house, which is located in Chelsea.
The two-storey property previously received little natural light due to many internal walls and small windows. The aim was to make the interior feel brighter and more open.
The first step was to gut the existing spaces, before adding two new floors – one in the basement and another at the top of the property. The front wall is the only original element that is left.
As the lower two levels could not have windows, the architects used skylights to bring plenty of light down from above.
The cream staircase connecting the house's four levels is located beneath one of these skylights.
"This careful spatial arrangement allows natural lighting of a four-storey property with windows only possible on the top two levels," architect Chris Bryant told Dezeen.
The staircase was designed to be as delicate as possible, so as not to obstruct light.
It features solid oak steps that are cantilevered from a supporting structure embedded in the walls. A cream steel stringer balustrade ties the two together and is further supported by the chord-like balusters.
"The stairs themselves were designed to be a permeable pebble to bring natural light to the lower floors," explained Bryant.
"It was important with the stairs to reduce the amount of visible structure as possible, both to create a sense of lightness but also reduce the visual clutter."
There are also two other skylights – one also piercing the main roof, and a third in the roof above the first floor. These are combined with double-height spaces and a structural glass floor.
On the ground floor, a new hinged front door can open up fully to a garage-cum-studio on the ground floor.
A living room is located behind. It overlooks a double-height dining room on the basement floor, where the architects also created an open-plan kitchen and television room, and a utility room.
Two bedrooms and bathrooms are located on the first floor, while the master suite occupies the second floor.
Contemporary and light finishes are used across the property. The kitchen units are white with grey surfaces, while the bathrooms feature white marble tiles with dark wooden cabinets.
Oak floorboards feature throughout and a matt grey paint covers the walls.
Alma-nac is run by architects Chris Bryant, Caspar Rogers and Tristan Wigfall. The studio has completed a variety of projects in London, including an extension to a 2.3-metre-wide house and the renovation of apartments with colourful herringbone patterns.
Photography is by Jack Hobhouse.