The governing body of Washington’s airports authority has put the brakes on plans to spend $7.2 million to build a three-story addition to its headquarters that would double the size of its boardroom.

“We have the funds allocated in the budget, but we should open it up to a discussion . . . and decide if this is a temporary situation or one that will last five years and beyond,” said Mame Reiley, a member of the board of directors of the Metropolitan Washington Airports Authority, which oversees Dulles International and Reagan National.

Reiley and Chairman Charles D. Snelling said the board would defer taking action until new members and the authority’s new chief executive, John E. “Jack” Potter, have a chance to evaluate the plans.

Board members were reacting to a report in The Washington Post this week about concerns over the timing of a planned expansion that would change the board’s corporate conference room setting to a city council-style chamber with a dais. State, local and federal officials have criticized the board for its management — and the rising cost — of the second phase of the Metrorail extension to Loudoun County.

The preliminary plans were prompted by concerns from board members and the authority’s fire chief about crowding at the board’s twice-monthly meetings. The board’s work on the 23-mile rail line at times attracts standing-room-only audiences to the second-floor conference room. It did so again Wednesday, when members voted to reverse course and embrace an aboveground location for the Dulles Metro station.

But some current and former board members opposed to the expansion said the high-level interest would probably wane when the authority hands over operation of the rail line to Metro over the next five years.

Even as board members said they had put off formal action on the expansion, work on the plans has continued. Additional documents reviewed by The Post on Thursday show a detailed design prepared for the airports authority last week. The consultant’s 42-page report recommends a “circular element of bamboo flooring with an inlay of stainless steel shaping the compass logo of the authority” for the boardroom and describes materials to be used, including “custom architectural woodwork with curved glass.”

Although board members have not made any formal decisions, Secretary Quince T. Brinkley Jr. said, “that has not stopped staff from putting a design together and moving along with giving us options.”

Five new members have joined the 13-person board since the vote in December to set aside $7.2 million in the authority’s 2011 budget. The project would represent less than 1 percent of the authority’s scheduled six-year capital program.

Potter, who began work last week, declined to comment because he is still getting up to speed on the authority’s projects, a spokesperson said.

The airlines and airport advocates who follow the authority’s work also said the transformation of the boardroom is unnecessary.

Richard P. DeiTos, who represents the airlines as executive director of the Metropolitan Washington Airlines Committee, said his group sees “no immediate or definitive need” for the project. The current room is “more than adequate,” he said, and larger meetings can be held in the authority’s first-floor conference rooms, which were completed in 2008 as part of a $5.8 million expansion.

Leo Schefer, president of the Washington Airports Task Force that helped create the authority in the 1980s, said the design would be “out of character” for what is essentially a board of directors for a company. “They are not an elected board of supervisors. They are appointed to run a major, very important corporation.”