The D.C. Historic Preservation Review Board agreed on Wednesday to designate the Warner Theater and Office Building as a historic landmark, after the owners of the building tried unsuccessfully to derail the designation process to retain control over the future of their building.

The 9-to-0 vote, with one abstension, came after two grueling days of hearings during which the owners' lawyer repeatedly attempted to have members of the preservation review board disqualified and evidence submitted by the D.C. Preservation League, the applicant in the case, thrown out.

"We feel we have followed the procedures required of a contested case and that we have followed our board rules," preservation board Chairman James T. Speight Jr. said as the board voted. The board agreed to preserve the exterior of the office and theater building and the interior of the theater, as well as to nominate the building to the National Register of Historic Places.

Board member Charles I. Cassell abstained from the final vote after William W. Taylor, an attorney for the Warner's owners, protested that remarks made by Cassell during the hearing indicated he was "already disposed" in favor of the landmark designation. Cassell said that he abstained because he did not want to jeopardize the legality of the board's decision.

"We'll win, eventually," J. Albert Weinberg, one of the principal owners of the Warner, said during the hearing. Neither Weinberg nor Taylor would comment after the hearing. Taylor said they did not know yet if they would appeal the decision.

Weinberg, a retired Washington businessman and investor, along with three other principal owners, acts as trustee for a group of investors who own the theater. South Trimble III, Julius Goldstein and Simon E. Eichberg are the other principals.

The Warner's owners never have said publicly what they would like to do with the building or site, but have said that the building would lose $6.5 million in value if designated a historic landmark. They have said that the theater's size and limited backstage space make modern productions difficult to stage.

The D.C. Preservation League has been trying to get permanent landmark status for the Warner for more than three years. Under the city's preservation law, a building or structure designated a landmark cannot be demolished or its exterior or site altered without obtaining a permit from the D.C. government and submitting plans for approval by the preservation review board.

The D.C. Joint Committee on Landmarks, which handled historic designations before the preservation review board was established in 1984, gave the Warner Theater landmark status two years ago, but the owners successfully fought in court to have that decision ruled invalid on technical grounds.

The court, however, did not restrict the preservation league from filing a new application, which it did early this year. The owners are appealing that decision on the grounds that successive applications are not allowed under the city's preservation law.

"It's a great move by the board, and we're very pleased," said Arne Sorenson, a lawyer from the D.C. firm of Latham Watkins & Hills who argued in favor of the DCPL's application during the hearings. "After two days of contentious battle, the Warner as a building stood out, and it clearly shows that the historic value of the building commands the action the board took."

Linda Powers, who worked with Sorenson on the case, said it is likely this decision also will be appealed. "We realize that we may just have started," Powers said.

The staff report from the city's Historic Preservation Division recommended that the exterior and interior be awarded landmark status, saying the building "contributes significantly to the cultural heritage or visual beauty and interest of the District of Columbia."

Board members cited the building's architectural character and star-studded history, as well as the fact that the Warner is the only remaining downtown "picture palace" in Washington, as their reasons for giving it landmark status.

"Vaudeville was a very special form of popular entertainment, and the shift from vaudeville to movies is an important part of the history of this country," said board member Evelyn Brooks-Watts. "The Warner is the last existing downtown theater we have that had both forms, and it exemplifies the process of that tradition."

The owners had attempted during the hearing to prove that the building had been changed too much to be considered historic. The orchestra pit, the marquee and some elements of the original facade are some of the things that have been altered since the building was constructed in 1924. The Warner was designed by the nationally known theater architect C. Howard Crane and by Kenneth Franzheim.

The board members, however, said they felt that the changes were part of the evolving history of the Warner and "not significant enough to jeopardize the building's historic character."

The DCPL filed letters of support for the theater's preservation from numerous groups and individuals, including comedian Red Skelton, who performed in vaudeville shows at the theater during the 1930s and '40s. "I think that the theater should be kept open," Skelton wrote. "They were temples, where people could go and daydream."

The D.C. Office of Planning also spoke in support of landmark status, saying that the theater was necessary as the future hub of an arts district in the old downtown area.

"This great theater space with some 2,000 seats is important for the cultural life and activity of downtown, indeed for the city and region," said John Fondersmith of the planning office, reading a statement prepared by D.C. Director of Planning Fred L. Greene. "Retaining this architectural and physical setting, with its long history of entertainment and cultural events, is a key step in retaining and increasing cultural activity in downtown."

Greene also said that the city government, "working with the private sector," was exploring how it could assist the owners in reconditioning and restoring the theater.

Weinberg, however, said during the hearings that, if the building were designated a landmark, the owners "would close the doors. . . .They will never make us use it as a theater."

The owners' appeal of the earlier court decision is scheduled to be heard by the U.S. District Court of Appeals for the District of Columbia sometime this fall.