The Glasgow School of Art’s historic Mackintosh building, which sustained heavy damage in a fire in June, will be rebuilt for a second time. The 110-year-old structure was undergoing a £35 million restoration following an earlier fire, in 2014, when it succumbed to flames again.

The school’s art director, Tom Inns, told the Guardian that officials were determined to rebuild “the Mack,” as it is affectionately known, even though experts raised concerns about the viability of its reconstruction. “There’s been a huge amount of speculation about what should happen with the site and quite rightly so, but from our point of view and that of the city of Glasgow, it is critically important that the building comes back as the Mackintosh building,” Inns said.

School officials have rejected calls to raze the structure and rebuild it from scratch, citing its distinctive and highly specialized internal spaces. The building, built in the late 1890s, is widely considered to be architect Charles Rennie Mackintosh’s masterpiece. “The beauty of the Mack was that in its design it really considered the internal environment needed for the disciplines that were housed in it,” the school’s head of architecture, Sally Stewart, told the Guardian. “In terms of the light within the studios, how the studios were scaled, to tinker with any of that is really tricky.”

Almost all of the rebuilding progress following the 2014 fire was lost in the June blaze, dealing a serious setback to the reconstruction effort just as it was nearing the final stages. The school had planned to reopen in 2019.

The second fire leaves much of the stonework in a dangerously unstable state and it’s unclear how much of the surviving brickwork and masonry needs to be replaced. The laborious process of manually dismantling and replacing the unsafe southeastern and western facades is already underway.

Fortunately, the building’s insurance policy should cover most of the reconstruction costs, but Inns warned it was too early to know if additional funds will be needed down the line. 

The cause of the second fire is still unknown. School officials are awaiting a report from the Scottish fire service, Inns said, and will “collaborate closely” with the investigators.