Architecture office Trewhela Williams has completed a minimalist renovation of a mews house in north London, adding a bespoke timber facade to animate its street-facing elevation.

The home, which is set in the Belsize Park Conservation Area, originally featured a disused garage that took up a sizeable portion of the floor plan on the ground floor and blocked off any connection to the street outside.

Trewhela Williams was brought on board to optimise the home's ground floor and convert the garage to provide additional living space.

The project focused on opening up the dark and insular interior to views of the quiet mews at the front and a small private courtyard in the rear.

Existing walls enclosing the garage were removed to allow this space to be incorporated into an open-plan living area that now extends across the full depth of the property.

The former garage door was replaced with a facade crafted from white-oiled oak that retains the proportions of the old door but provides greater visual interest when viewed from the mews.

"The existing garage doors along the street create quite a closed and guarded frontage," Trewhela Williams told Dezeen. "We wanted to create something that's visually animated and provides a more open and engaging elevation."

Angled oak fins positioned in front of the large window function as a brise soleil, allowing daylight to enter and providing limited views of the street from inside while maintaining privacy.

From the entrance to the mews, the fins appear to form a solid wooden volume covering the window. But their geometry seems to shift and becomes more permeable as people approach the house.

The bespoke joinery forms a pared-back structure comprising simple planes, volumes and edges that was influenced by the minimalist wooden sculptures of American artist Donald Judd.

Trewhela Williams specified a frameless glazing unit with concealed fixings to enhance the sculptural simplicity of the carpentry.

The windows include an espagnolette mechanism that allows them to tilt to facilitate cross-ventilation through the house or pivot open so the family's pets can go outside.

The studio applied a pared-back material palette with a focus on tone and texture to create a minimalist interior scheme.

Walls and ceilings are rendered with a subtly textured Danish plaster that is complemented by the warm Douglas fir flooring and terrazzo tiles speckled with marble aggregate.

A worktop made from cloudy white Mugla marble extends along the full depth of the property – from the entrance hall and storage area at the front to the galley kitchen, dining space and snug towards the rear.

"Whilst the interior is pared back and displays the traits of minimalism in its simplicity, there is real harmony and beauty in the details," Trewhela Williams explained.

"There are very few materials and details within the home, so each one has been meticulously chosen to harmonise and create a space that feels warm and calm rather than being cold or sterile."

An existing courtyard at the back of the house is now visible and accessible through an enlarged opening, which fills the full height and width of the rear elevation.

A minimal pivot door can be opened to create a seamless connection between the interior and the courtyard that also functions as a lightwell drawing daylight into the adjacent living spaces.

The courtyard is paved with large-format concrete tiles and is enclosed by walls covered with natural clay plaster, harmonising with the textural palette of the interior.

The courtyard houses a simple linear bench and a cylindrical plant pot, with their geometric forms providing visual structure while a lone acer tree adds a burst of colour.

Despite being situated in a conservation area, the bold design for the new facade was complimented by the local planning authority, which said it provided a positive precedent for neighbours considering similar conversion projects.

"It was a big relief," said Trewhela Williams. "A lot of conversion and extension projects focus on the rear of the property but here we were working on the front so we had to tread very carefully."

"Thankfully the planners were very supportive," the studio added. "We've also been contacted by some of the neighbours about doing something similar with their properties, so there is an appreciation for what we've achieved here."

Previously, the studio has created an extension to an Edwardian house in north London featuring a brick wall that extends out from the kitchen into the garden.

The photography is by Lorenzo Zandri.