A proposal to establish a special restrictive zoning district around the U.S. Capitol was given preliminary approval by the D.C. Zoning Commission this week, despite concerns from commercial-property owners that their property values would drop if the proposal was adopted.

In a 3-to-0 vote, with two commission members not voting, the zoning board approved the proposed rule-making to create a Capitol Interest District to restrict development in the area roughly bounded by the Capitol on the west, F Street NE to the north, Sixth Street on the east and Virginia Avenue SE to the south.

Architect of the Capitol George White proposed the special overlay district earlier this year, after he concluded that existing zoning controls -- which include the restrictions of the Capitol Hill Historic District -- were not sufficient to assure "harmonious" land uses and buildings for the area.

As drafted by the zoning commission, the overlay district would restrict new construction to the height and bulk of the row houses that dominate the 60-block area.

The proposed district would effectively reduce allowable zoning on a handful of properties in the area, all commercial lots with zoning that allows for heights ranging from 50 to 90 feet, and floor area to lot size ratios (FAR) from 2.5 to 6.5.

Under the overlay, development would be limited to 40-foot buildings with a maximum FAR of 1.8.

"The problem of devaluation of property is one that arises with every zoning action," said White, who has pushed for months to establish a protected transition zone around the Capitol. "But the courts have held that no one has a right to a particular land use."

David Colby of the D.C. Office of Planning said that most of the residents and merchants who testified at zoning commission hearings earlier this fall said that they expect property values overall actually to increase with adoption of the proposed special district.

"It is perceived as a protection, one that will improve the area and enhance its character," said Colby. "That area could be as special as Georgetown some day." The proposal has been supported from the beginning by the Capitol Hill Restoration Society, the Capitol Hill Association of Merchants and Professionals, Advisory Neighborhood Commission 6-A and a majority of the residents who testified.

The proposed district would also specifically exclude a number of commercial and industrial uses from the area, such as parking garages, automobile rental agencies, public utility pumping stations or electric substations, radio or television broadcasting studios, antenna towers over 50 feet high, parcel delivery services and auto and boat sales. No new gas stations or parking lots would be permitted, though those that exist would be allowed to continue operations.

The zoning commission did not include in the proposed district a clause that would allow existing nonconforming uses in the area to rebuild to their present heights and densities in case of fire, saying that special exceptions could be made in the future by the Board of Zoning Adjustment.

The proposal was endorsed by the National Capital Planning Commission, the agency charged with protecting the federal interest in Washington, in June. The NCPC staff said that the proposal would "contribute significantly to the protection and enhancement of the Capitol grounds and . . . reduce pressures to demolish existing buildings which contribute to the historic district and thereby protect the integrity of the district as a whole."

The NCPC will have to approve the final proposed rule-making before the zoning commission can enact the new district. Zoning officials said they expect the proposal to have final approval by early next year.