New York architecture studio Diller Scofidio + Renfro has unveiled images of a grey, sculptural expansion to The Broad museum in Los Angeles, which the studio created nearly a decade ago.

Located adjacent to The Broad, the 55,000-square-foot (5,109 square metres) expansion will contain additional art galleries, storage, performance space and two open-air courtyards.

Designs show a rectangular building elevated above a plaza. Curved-edge windows are pushed into its facade with the edges of the glazed openings appearing to pull the exterior of the building inwards. The studio said the expansion will complement the existing structure while retaining distinct characteristics.

"I think of the new building as a companion to the existing Broad," said Diller Scofidio + Renfro partner Elizabeth Diller. "The pair shares DNA, but each has its own distinct character and purpose in constant dialogue with its counterpart."

The form was derived from the "veil" and "vault" concept of the original museum, which consists of a honeycomb "veil" that folds over an organic, large grey "vault" that makes up the interior.

"The exterior of the expansion echoes the surface appearance of the vault – as if this core had been exposed and 'unveiled' – symbolically expressing The Broad's commitment to access while playfully inverting the visual vocabulary of the current building," said the team.

The expansion will host galleries on the first, second and third floors and second-floor storage racks that will house additional artworks, which visitors will be able to move through.

It also will pay homage to the circulation of the first structure, in which transitional areas were given special care, according to the team.

"The original Broad was conceived as an unfolding experience starting in the lobby, traveling up the escalator piercing the vault, landing in the third-floor gallery immersed in the collection, then snaking down through collection storage on the way back to the street," said Diller.

"The challenge of adding more space to the building was to retain this intuitive circulation and logic while introducing a set of completely new experiences for the visitor."

An interior rendering shows a large, white cube gallery with track lighting, wooden flooring and contemporary artwork, with a curved window towards one corner.

An outdoor plaza located underneath and around the expansion will connect the museum to a local metro station.

The project will break ground in 2025 while the Broad remains open. Expected completion is set for 2028, "before Los Angeles hosts the 2028 Summer Olympics" notes the team.

When The Broad opened in 2015, writer Mimi Zeiger called it an "elegant exercise in mundanity". In 2022, Elizabeth Diller said The Broad was designed to feel "extremely welcoming" in a Dezeen-produced video series dedicated to concrete buildings.

Diller Scofidio + Renfro recently completed a performing arts centre on a Massachusetts campus and had its first single-family residential project in the Hamptons photographed years after its completion.

The images are by Plomp