The Barbican will close its doors for 12 months from June 2028 as it undergoes a multimillion-pound renovation that its leaders say will secure its future.

The arts organisation’s Beech Street cinemas will remain open but its theatre, music venue, conservatory and visual arts galleries are set to shutter as the overhaul of the 43-year-old building begins in the lead-up to its 50th anniversary in 2032.

The main Barbican site will close its doors in June 2028 and reopen in June 2029, but some disruption will happen before that as the foyer, lakeside area and internal control room are all renovated.

The conservatory, which is open only for a few hours at the weekend and currently has netting to stop falling glass, will close earlier, in 2027.

Philippa Simpson, the director of buildings and renewal at the Barbican, said the work could not be completed while the site was open to the public as it would be too dangerous, but that it was essential to secure the site’s future.

“If we want it for another 50, then you’ve got to rip the plaster off and do it now and let it thrive for the next 50 and not just limp along,” Simpson said.

During the renovation, the building’s ventilation system will need to be shut off, rendering it unsafe, while major jobs – such as replacing electrical systems and safe removal of asbestos – will require closures. The work will also reduce the Barbican’s carbon use by 40%, according to Simpson.

It is only the second time in its history that it will have closed for a sustained period, the other being during the Covid-19 pandemic.

That means the London Symphony Orchestra, which has called the Barbican home since it opened, must perform elsewhere, as will the Royal Shakespeare Company.

Dame Kathryn McDowell, the orchestra’s managing director, said the LSO was committed to providing a 2028-29 season “across London and the UK” and confirmed that the LSO St Luke’s venue would remain open throughout the closure of the Barbican.

The Barbican also plans to continue having a presence in the capital, with events outside of its City of London base. “When we talk about closure, there’s a physical side of it, but actually, existentially we’re still present,” Simpson said.

It is not clear what will happen for the 400 Barbican staff, who were informed of the closure on Thursday evening.

The organisation did not rule out redundancies, saying all options were being considered. Secondments at the Barbican’s founder and main funder, the City of London Corporation, were another potential option.

Simpson said: “Obviously, we’re already talking to unions and will work really, really closely with them. It will be done in consultation as transparently and as carefully as we possibly can and make sure that it’s actually worked through rather than rushing.”

The GMB senior organiser Lisa Bangs said the union welcomed the “much-needed refurbishment” but would be pushing for casual and permanent staff to keep their jobs.

She said: “We want to ensure that staff are retained and protected during these works and we will always advocate strongly for our members. The Barbican have been in touch and we look forward to working constructively with them as plans develop.”

The Barbican has just announced a new chief executive, Abigail Pogson, who will oversee the capital project, the first major renewal work in its history. She is the latest arrival at an organisation that has had several changes in leadership over the past five years.

In 2021, Sir Nicholas Kenyon resigned as managing director after staff told the Guardian that the Barbican was “institutionally racist”. He was followed by the former BBC arts correspondent Will Gompertz, who left to join the Sir John Soane’s Museum after being in the job for only two years.

Devyani Saltzman started as director of arts and participation in 2024, and is one of seven senior leaders installed after the Barbican replaced the managing director model. They all report to Pogson, who will start in January 2026.

The Barbican first revealed plans for the renovation work in May this year. The grade II-listed cultural destination had “deteriorated significantly” over the years and needed significant work done to improve it, according to the plan.

The first phase of the project will cost £231m and be led by Simpson, who did a similar job for the Young V&A in east London, which won museum of the year in 2024. The overall bill is estimated to be £451m.

Opened in 1982, the Barbican arts centre is a unique cultural institution. The centre’s cultural offering was originally primarily designed for the 4,000 residents of the flats set around the site.

Today, more than 1.5 million people visit annually, making it one of the most popular cultural attractions in the UK.