The New York City Landmarks Preservation Commission has approved Selldorf Architects' renovation and expansion plans for the city's Frick Collection museum, despite ongoing protests against the "harmful" project.

Approved during a hearing yesterday, 26 June 2018, the proposal by Selldorf Architects will involve the largest overhaul of the Frick Collection since it was transformed from the home of industrialist and collector Henry Clay Frick into a museum. Completed in the 1930s by architect John Pope, the overhauled building has undergone several extensions.

Selldorf Architects' scheme includes opening parts of the original Frick residence to the public for the first time, restoring its Russell Page-designed garden, and adding an extension to the museum's library.

However, the proposal has received much opposition from preservationists since it was unveiled earlier this year.

Campaigns aim to protect museum's Russell Page Garden

The Cultural Landscape Foundation sent an open letter to the New York City Landmarks Preservation Commission ahead of the hearing, outlining concerns for the future of the garden on East 70th Street. It warned that Selldorf Architects' proposal still "nullifies Page's design".

Completed by the British landscape architect in 1977, the green space also formed a point of contention for a previous Davis Brody Bond-designed extension that was abandoned in 2015 after artists protested against the plans to build on the green space.

Stop Irresponsible Frick Development, a protest group launched in response to the project, similarly raised concerns for the garden at a press conference ahead of yesterday's hearing. It was held on the steps of City Hall and attended by Frick's great-granddaughter, Martha Frick Symington Sanger, along with architects and preservationists.

Preservationists raise concerns for "harmful" expansion

During the event, the group also called for the museum's Music Room – which will be removed during the expansion – and its reception hall to both be designated as landmarks.

"The Frick absolutely must explore less harmful alternatives before moving forward with a plan that will destroy or significantly alter numerous historic and landmarked aspects of the Collection, including the Russell Page Garden and John Russell Pope-designed Music Room," said Frick Symington Sanger in a statement.

Stop Irresponsible Frick Development's other concerns include the commercialisation of the museum, the introduction of the cafe near to the garden – which it believes could cause it to become infested with rats – and maintaining consistency with the original design.

"When he passed, my great-grandfather Henry Clay Frick left his home to the public as a house collection, a special gem for New Yorkers to enjoy in an authentic and tranquil setting," Frick Symington Sanger said.

"With the Frick Collection's new proposed expansion, his vision and legacy are under threat, and the public has been unfairly denied a voice in the review process."

Frick Collection and Selldorf defend proposal

But the Frick Collection argues that it has already listened to criticisms, and slightly altered the scheme following a public hearing in May 2018.

"Public engagement has been critical to our process and our plan has benefited from this ongoing dialogue," said the museum. "We value the time and dedication of the numerous individuals who have been involved in this process, and are looking forward to embarking on the next phase of planning."

"We are grateful for the support we received from the Landmarks Preservation Commission, which has recognised the strengths of our plan to upgrade our building and to ensure the long-term vibrancy of The Frick Collection."

Selldorf Architects founder Annabelle Selldorf has described the expansion as subtle and suited to the existing building. For example, the limestone cladding for addition to the rear of the Pope-designed library was chosen to match the existing building's material.

"Our proposed design is the result of an unwavering commitment to maintaining the intimate experience of viewing art at the Frick that is unique and special to so many – myself included," said a statement from Selldorf in April 2018, when the proposal was first revealed.

Now with the Landmarks Preservation Commission's consent, construction on the Frick Collection's expansion is set to commence in 2020.

It is among a number major gallery projects by the firm, which Selldorf founded in 1988. Others include a Los Angeles outpost for Switzerland-based art gallery Hauser & Wirth and new spaces at the Clark Art Institute in Massachusetts, designed with architect Tadao Ando.