The Arlington County Board voted Saturday against declaring the century-old Wilson School a historic building, clearing the way for its demolition and the development of a school eight times its size.

More than a dozen residents, including an 85-year-old woman who attended the school between 1936 and 1942, pleaded with the board to designate the building a local historic district as a way of forcing the school board to incorporate the red-brick structure into its plans for a new 775-student school. But opponents argued that the distinctive portico, columns and cupola were removed from the school in 1963 and that it would cost millions to retrofit the structure to meet today’s building codes.

“It would cost a fortune to do it right . . . and we have a lot of needs in this county,” said board member Libby Garvey (D), pointing out that the county has saved several other historic schools. “There’s a time in life when you have to let go of things.”

Built in 1910, and first called Fort Myer Heights School, the school was renamed in honor of President Woodrow Wilson, who used to drive by it and wave to the children. It is now used only on Saturdays by a small Mongolian language and cultural school. School officials, dealing with serious overcrowding, want to create a building to house students with special needs as well as H-B Woodlawn Secondary Program. They say moving to the location on Wilson Boulevard at North Quinn Street would allow them to use the current H-B Woodlawn building for a middle school.

The plan has not been met with universal acclaim. Some neighborhood residents say the school system never gave serious consideration to preservation. John Chadwick, the school’s assistant superintendent of facilities and operations, said Saturday that the schools prefer that its architects start designing from “a blank slate.” A rough estimate of the cost of integrating the old building with a new one could cost $3 million to $5 million for the exterior and $2 million to $3 million for the interior, he said, which opponents said were too high.

The County Board, which rejected the historic designation request on a 4-to-1 vote with only board member J. Walter Tejada (D) in opposition, unanimously agreed to ask the schools to work with county staff and the community to “identify and incorporate ways to memorialize and commemorate” the school’s historical value in its design.

The school shares a tract of land with a county fire station and the small, but heavily used, Rosslyn Highlands park and playground. The county signed a letter of intent two years ago with Penzance, a private developer, to lease or sell the county-owned portion of the land for a new mixed-used residential and commercial project. The developer would replace the fire station and dedicate part of the property as public open space.

Residents who live near the park and use it have protested the possible loss of the playground in the densely developed area, where public open space is rare.

“Why should Rosslyn give up a park to pay for a fire station?” asked Anna Duvan, a member of the county’s West Rosslyn study committee.

Board chairman Mary H. Hynes (D), who noted that the adjacent school will have a large public athletic field, said the board wants to create as much contiguous green space as possible and has asked county staff to report back in a week or two with ideas about how to do that.

“It’s an important community conversation, and we have heard what you said,” she said.