Decisions by the Board of Zoning Adjustment recently cleared the way for two projects in which developers will save historic buildings-a turn-of-the-century mansion in Mount Pleasant and three Victorian rowhouses in the 1700 block of N Street NW.

The board voted to grant variances that will allow developer Semih Ustun to build a four-story addition to Adams House, a landmark at 1801 Park Rd. NW, and to convert the building and its addition into 13 housing units.

The board granted variances and exceptions so that John O. Antonelli, stepson of developer and parking lot operator Dominic F. Antonelli Jr., can build a 90-foot addition behind three townhouses at 1752, 1754 and 1756 N St. NW and turn the enlarged structure into an office building.

The Mount Pleasant community, led by a group called Patrons of the Adams House, which was formed specifically to save the colonial revival mansion built by wealthy printer Byron S. Adams, supported the developer's requests for variances at a hearing last month.

Dupont Circle residents, led by the Dupont Circle Citizens Association , the Association for the Preservation of the 1700 block of N Street and the Dupont circle Advisory Neighborhood Commission, opposed the Antonelli plan, both in BZA hearings and in negotiations held by the state historic preservation officer. Anne Sellin, zoning chairman of the Dupont Circle citizens Association, said community groups will ask BZA to reconsider its decision.

Walter Lewis, a member of the BZA, asked his colleagues to grant the variances in the Adams House case because "the community worked with a developer to retain a historic building while providing needed housing."

After more than a year of court battles, hearings and negotiations, an agreement was signed Sept. 1 by the developer and by representatives of the Patrons of the Adams House, Don't Tear It Down Inc. and Advisory Neighborhood Commission 1E. The agreement commits Ustun to preserve the Adams House, to convert it into two residential units and to follow an architectuarl and landscaping plan worked out between the community groups and the developer's architect with the help of Francis Lethridge, a member of the Joint Committee on Landmarks. The committee is made up of city and federal government representatives.

Janet Dyke, who lives at 1741 Park Rd. NW near the Adams House and who helped form the organization to save it, called the agreement " a good compromise" and "the lesser of two evils."

"The setting will be substantially altered by the additon," said Dyke's husband, James, who signed the agreement on behalf of the Patrons of the Adams House. "We'd prefer to see it a single-family house again, but the developer didn't want to sell it. We had no recourse for saving the Adams House, which is truly a significant building."

The negotiations that led to the agreement were required under the 180-day delay-in-demolition regulation for historic buildings. When the developer originally applied for a demolition permit to tear down Adams House in order to build six townhouses, the building did not have landmark status. Community leaders went to court to prevent issuance of the demolition permit on the grounds that the Adams house and neighboring buildings on the south side of the 1800 block of Park Road were the subject of a pending landmark application. The community won in court, and the buildings were later declared landmarks.

"I originally wanted to build six new houses," said developer Ustun in a telephone interview."That would still be best from a strictly financial point of view. But the people in the neighborhood felt so strongly about the house that I felt I had to make a comprosmise."

Ustun said that construction on the project would start early next spring.

Negotiations also were held during a 180-day delay-in-demolition period on the N Street townhouses, but no agreement was reached. Community representatives who participated in the negotiations wanted Antonelli to reduce the size of his proposed office building but he refused, saying that he was already making a financial sacrifice by by retaining and refurbishing the townhouses.

Ccommunity representatives said Antonelli's proposed office building would add to the congestion in the area and would erode the fragile border between residential Dunpont Circle and the "new downtown" commercial area.