The Chicago Department of Buildings approved a permit for demolition at the James R. Thompson Center affecting the iconic building’s interior and facade.

The Helmut Jahn-designed Thompson Center previously served as a state office building before it was sold in July 2022 to JRTC Holdings, a company led by real estate developer Michael Reschke.

Google has a “build-to-suit agreement” with JRTC Holdings to buy the Thompson Center once renovations are complete. The internet giant is expected to begin occupying the building in 2026, the company said in July 2022.

The newly approved demolition work is expected to cost $6 million, permit approval records show. The permit listed the work as just the second phase of a “multiphase” project. Reschke previously estimated overhauling the 17-story glass-and-steel structure would take about two years and cost roughly $280 million.

The permit calls for the “interior demolition & demolition of exterior building facade.”

Jahn, the namesake firm of the building’s designer, is the architect for the redevelopment. The firm’s initial renderings for the redevelopment showed significant changes to the building’s facade, including larger glass panels, altered colors and an emphasis on greenery. The renderings also showed similar changes to the building’s towering atrium.

The glass on the facade installed decades ago is not adequately insulated, Jahn President Evan Jahn said Tuesday.

“I don’t think it should come as a shock to anyone that the original facade will be taken off,” he said.

He described the demolition as “just a step in modernizing the building,” and declined to share details on how the building will be remodeled.

A Google spokesperson declined to comment on the remodeling. Reschke did not immediately respond to calls and texts about the ongoing redevelopment.

[ Google plans to open in the Thompson Center by 2026. Will the tech giant help revitalize the Loop? ]

Continued demolition and remodeling might significantly alter the historic building, said Ward Miller, executive director of Preservation Chicago, a nonprofit group focused on protecting historically significant architectural structures.

“From what we’re seeing, there’s a chance that this building could really lose its integrity and look like a mylar balloon if we’re not careful,” Miller said.

The Thompson Center is one of Chicago’s most important architectural marvels, Miller argued. It was one of the first major projects by the star architect Jahn and has become an important city landmark, he said.

Miller praised JRTC and Google’s decision not to demolish the building but criticized them for not sharing more recent renderings. He called on local officials including Mayor Brandon Johnson to encourage the companies to maintain the building’s character.

A “sensitive repurposing” doesn’t have to adversely affect the building, he said. He shared hopes the redevelopment would maintain the building’s plaza, colors and atrium.

“We could save everything that’s important. It could still be renovated and look like it’s brand new,” he said.