French firm Toledano + Architects has renovated an apartment in the seaside town of Biarritz, adding a raised sleeping area that looks out towards the nearby lighthouse through a large bay window.

The apartment was originally the entrance hall of a typical 1930s villa designed in the Basque style, with a bay window facing the lighthouse and the Atlantic Ocean.

Architect Gabrielle Toledano's Paris-based studio was tasked with converting the space into a holiday residence for a couple in their sixties, who enjoy surfing and the culture of the Basque region.

The clients wanted a place to sleep that could also be used to host dinner parties, so the architects suggested adding a mezzanine level to optimise the compact 70-square-metre footprint.

Fluid forms inspired by the seaside location feature throughout the apartment's interior, from the sculptural wooden steps in the living space to a wave-like wall in the bedroom.

"The waves and the sinuous coast set the tone for the project, entirely drawn in curves," Toledano said.

The new upper level was built as an entirely independent structure to minimise its impact on the existing space. It contains a bed oriented towards the view and a curving wall that conceals wardrobes and the bathroom.

The bathroom was designed like the cabin of a boat and features a porthole-like circular window that provides an ocean view from the shower.

Another important element within the space is the existing bay window, where the clients requested seating so they could look out across the ocean.

The window frames are made from steel to minimise the thickness and maximise resistance to strong winds, while the glazing disappears into pocket openings in the walls to open the space up to the outdoors.

"The bay window is the main character of the space because of the spectacle it offers, like a painting in eternal movement," said Toledano, describing the dynamic view towards the horizon.

A five-metre-long bench extends the full length of the living area, integrated into a four-metre-high bookcase that frames the bay window and provides space for showcasing the couple's photography collection.

The kitchen is tucked beneath the mezzanine and can be completely concealed behind a set of bi-fold doors. Built-in joinery that flows along the walls incorporates a toilet positioned in the back corner.

A minimal material palette used throughout the interior aims to lighten the space and provide a connection to the maritime setting.

Structural elements and walls are painted light green to complement the oak flooring and joinery, while stainless steel surfaces add a contemporary reflective detail that references maritime architecture.

Rather than completely gutting the space and starting from scratch, Toledano looked to use what was existing and limit her interventions to help achieve a more sustainable outcome.

The original parquet floor was carefully restored and the existing front door was retained and adapted to fit beneath the mezzanine.

Most materials used for the interior were sourced from close by and local artisans were employed to fit out the space. The bay window was upgraded using solar glass to help control the temperature, while internal blinds are used to filter the sun.

The Lighthouse apartment features on the shortlist for Dezeen Awards 2024 in the residential interior category, alongside projects including a renovated Parisian townhouse that utilises biomaterials like rammed earth and cross-laminated timber.

Founded in 2013, Toledano + Architects focuses on modularity and sustainability in its projects, which include a Paris apartment featuring a sinuous plywood wall and a Tel Aviv penthouse with a folded steel staircase suspended at its centre.

The photography is courtesy of Toledano + Architects.