Residential resales are down because gas and mortgage money are hard to get -- and expensive, too.

But Katherine C. Peck, who heads one of the area's largest general real estate brokerage firms, is keeping her cool.

The president of Hugh T. Peck Propeties Inc., of Kensington, acknowledges that there has been "a little downswing in the market" recently, but her daughter, Katherine Ann, the exceutive office manager, notes that the firm has "always done well when the general market has been bad."

"Traffic is off but we're not losing any sales. In fact, our June volume was ahead of June 1978," said another Peck daughter, Cynthia Jean. She is director of advertising for the firm, which has 23 offices.

The Peck firm was founded in 1946 by Hugh Peck, wgo died three years ago. Since his death, it has been headed by his wife, Katherine, and has grown from 257 agents to 600. Mrs. Peck has had her real estate license since 1951; she formerly managed an office in Wheaton.

"We are most fortunate to have Willie Gutridge, who was Hugh's righthand man, as vice president and general manager," Katherin Peck said. "Hugh's sister, Ruth V. Maddox is secretary-treasurer." Gutridge is the only person outside the family with a financial interest in the firm.

Her daughters agree with their mother's assessment that while it's "a man's world . . . women seem to be more equal in real estate than in most other lines of work.

"Eighty percent of all sales are made by women," Mrs. Peck points out.

Asked about the highly competitive nature of their business and what it takes to survive in a tough market like the current one, Kathy Peck said: "We do not discuss competition; we try to ignore it.

"We know our people work harder when sales are harder to make. That's what happened in 1973-74, when we had good years."

Cynthia, known as Cindy, said that her father's interest in the business has rubbed off on his family. "I remember driving around with daddy," she said. "If we were near an office, he always stopped for a few minutes. We have a breakfast or luncheon meeting for everyone in the firm every three months to build a togetherness."

The Peck firm plans to survive the current market downturn by lining up more FHA and VA loans for prospective buyers, using mortgage assumptions when possible and urging sellers to take back financing. Those are conventional approaches to a tight market.

The Pecks say buyers in this area are mainly interested in resale houses piced between $65,000 and $90,000. The firm's average resale price has risen form $55,000 to $79,000 in three years. Kathy Peck said that the Peck office in Takoma Park is "red hot" these days, largely because there's a Metro station serving that area now.

"All Metro-related homes are selling at fantastic prices as the result of the gas crisis," she said.

Will the Peck firm ever join a national franchise?

"Not a chance," Kathy said. "This is a personal business. We are expanding into the counties and are looking for tright office in the District. But our name and family-run tradition are important to us and our people." CAPTION: Picture; Mrs. Peck, seated, with Kathy Peck, Ruth Maddox, Willie Gutride, Cynthia Peck. By Lucian Perkins -- The Washington Post