The Arlington County Board defied an appeal by federal officials yesterday and approved construction of a 14-story office building that federal planner fear will mar the westward view from the Mall.

Calling arguments by a spokesman for the National Capital Planning Commission "stupid" and "nonsense," Board Member John W. Purdy suggested the federal agency spend its time worrying about the other side of the Potomac.

I suggest you (stand) at the base of the Washington Monument and you won't find anything to be proud of." Purdy told Richard Westbrook, the planning agency's zoning chief."You don't have any right to come out here and criticize what we're doing."

Startled, Westbrook asked Purdy if he was referring to the view of the White House and the Federal Triangle. Purdy said he was.

Approval of the high-rise to be located two blocks from Arlington Courthouse, was the latest confrontation between the county and federal officials over the heights of a building now under construction along the Virginia side of the Potomac. The federal government, which has failed to block the high-rises in the courts yesterday went before the five-member county board to plead that the latest building also would mar the skyline of the nation's capital and should be chopped down to six stories.

Several Arlington residents also urged the board to reject plans for the concrete, box-shaped building similar to those which line Washington's K Street. The building proposed by developer Herbert Morgan a former arlington Republican state delegate, will be located on a lot bounded by N. 14th St., N. 15th St., N. Taft St. and N. Troy St. on a tract once owned by Arlington that Morgan obtained by "swapping" a smaller parcel he owned and paying $250,000 to the county.

"It's too high, too big, too much." said Louise Chestnut a citizen activist. "There's too much concrete. This county underestimates itself. We talk as if we have to grab everything that comes along and we're sitting on top of the real estate everybody wants."

Morgan, a childhood friend of and trusted advisor to Board Chairman Walter L. Frankland Jr. admitted that his building, which will be flanked by a large concrete plaza, will be massive "It has to be in order to justify costs," said Morgan. "It will give some people in the upper floors a very nice view of the Capitol."

Board chairman Frankland reminded his colleagues that the development would improve Arlington's tax base. "They [federal officials] talk about these things but they're not willing to compensate us for the tax loss if we conform to the height loss," said Frankland who defended the design by saying "If there weren't concrete, there wouldn't be any buildings."

Board Members Ellen M. Bozman and Dorothy T. Grotos voted against the high-rise. Grotos said she thought it was too tall and Bozman said she wanted it redesigned.

The next step is up to the federal government, whose officials will meet later this month with Arlington leaders about building heights. Earlier this month officials from the Department of Housing and Urban Development threatened to withhold federal mortgage insurance and rent subsidy funds from developers of a 24-story high rise Arlington apartment building unless the structure is reduced five stories.