Thirty-three-year-old Christopher Dorment isn't satisfied with having carved a niche as the builder of the lowest-priced housing in upper Potomac. He also wants to become known as a specialist in another type of house he builds, low-priced units on two-acre lots.

As president of Rocky Gorge Communities Inc., Dorment keeps an eye on all phases of creating new homes in three small communities. Two are in Virginia and two are in the Potomac area. Prices start at $143,700 for homes on one-quarter-acre and one-half-acre lots in Shadow Walk at Walton Woods off Franconia Road in south Alexandria. Other Dorment houses cost $250,000 and $275,000 at River's Edge on the former Christian Heurich tract near River Road in Potomac, where new models soon will be ready on two-acre lots. Skylights in bathrooms will be among the features there.

The Rocky Gorge firm, based in McLean, also has been building single-family houses on two-acre lots in Potomac Chase Estates on Query Mill Road in Potomac. Prices range from $185,000 to $192,000. The firm also has houses priced form $62,000 in Richland Hunt on Hunter Mill Road near Rte. 7. in Fiarfax County. Eight new homes will be built in the Somerset area of Chevy Chase this summer.

"We have basically nine different house models that we adapt to suit clients," Dorment said. "The Collins-Kronstadt frim designs them to have four bedrooms and two and one-half baths and a center hall entrance. Most are two stories but we have two split-level variations. My partner, William (Jake) Robins is the real builder on the secene."

Rocky Gorge has about 60 on its payroll. Dorment praised the group and said that nobody stays without producing - "and that includes a laborer making $4.50 an hour."

A former Wall Street attorney who was an under-graduate at Georgetown University before going to Fordham University, Dorment grew up in Montclair, N.J. His late father was a developer who built in the Towson area of Baltimore.

"After three years on Wall Street doing corporate law, I realized that what I was really not making any real difference in anyone's life," Dorment said. So he chucked the law and hired on as apprentice foreman with his older brother, John Dorment, who builds in Baltimore and Prince George's counties.

A year later, Chris Dorment formed an alliance with Jake Robbins, who had ground for 19 two-acre houses in the Ashton area of upper Montgomery County. They started in late 1974 and sold out in little more than a year 1

This year, the firm probably will have a volume of $10 million and complete more than 50 houses, Dorment said. But he views the current market as "unsettled." It's not the high interest rates but "the constant drumbeat of terrible economic news," he said. "People get edgy and lose confidence." CAPTION: Picture, One of the houses built by Rocky Gorge Communities on a two-acre plot in Vienna.