WASHINGTON (AP) — The White House said Thursday that it was not feasible to save the East Wing because of structural issues, past decay and other major concerns as officials shared details of President Donald Trump’s planned ballroom at a public meeting of the commission charged with approving it.

Josh Fisher, director of the White House Office of Administration, said an unstable colonnade, water leakage, mold contamination and other problems made it more economical to tear down the East Wing to make room for the $400 million ballroom than to renovate it.

“Because of this and other factors, the cost analysis proved that demolition and reconstruction provided the lowest total cost ownership and most effective long-term strategy,” Fisher told members of the National Capital Planning Commission.

It was the most comprehensive explanation to date for the dramatic demolition of the East Wing, which caused a public stir when it began in October with little advance notice.

The commission’s chairman, Will Scharf, who is also a top White House official, said he thought the project would ultimately be approved.

The project’s architect, Shalom Baranes, joined Fisher to provide a high-level view of the proposal to the commission. Baranes showed the panel renderings of the ballroom and views of the White House complex from the north and south with the addition.

Baranes said the design could include adding a second story to the West Wing colonnade to help make the White House more uniform with the new ballroom on the east side. But such a step would also dramatically alter the iconic space outside the Oval Office.

Fisher and Baranes said the project includes more than just a ballroom, and will also streamline visitor access to the White House and make unspecified improvements to Lafayette Park across the street.

Some of the 12 commissioners raised concerns, most vocally Democrat Phil Mendelson, who asked several questions about the ballroom’s size and location and whether those might change going forward. Baranes said “anything’s possible,” but added that the plans had been thoroughly studied.