If you are unconvinced that Americans are sold on home ownership, take it from author Adam Smith in the March edition of Esquire that the total value of all single-family houses in our nation exceeds the value of all the listings on the New York Stock Exchange. Smith did not mention that more than two-thirds of all Americans now live in their own houses, with the number of single-family units estimated in excess of 50 million. Even at a conservative average value of $50,000, that would put the total in excess of $2 trillion! Smith seems to be preoccupied with America's expensive houses, escalating residential values and cocktail party talk about buying and selling them. But the basic American ambition for modest home ownership currently is suffering from still-rising mortgage rates.

A recent round-up of statistics on area resales of homes of during January showed a 17 percent downturn from January 1979. Three were 3,192 resales a year ago in January but only 2,639 this January. The decrease in sales was heaviest in Montgomery County and the District, both more than 30 percent.

Although his forecast is more than two weeks old and came before the most recent Fed money tightening move, economist Peter Treadway of the Federal National Mortgage Association predicted that housing starts will be about 1.5 million this year and nearly 2 million in 1981. He added: "While the next few months may see a pause in the upward climb in house prices, that situation is not likely to continue. House prices are likely to outpace the CPI (consumer price index) throughout the early 1980s."

Alan Trellis, a young custom-style home builder who has been doing energy-efficient, solar-powered comtemporary houses in the suburban Maryland market, is newly excited by his entry into the downtown Baltimore market. He has acquired a row of older houses on W. Biddle Street and plans to redo them thoroughly and still be able to offer them to the public in the $55,000 range. A resident of Columbia, Md., Trellis said he is oriented to Baltimore for sports and culture -- and now home restoration.

Sale of 340 acres near Dulles Airport to a group of foreign investors for more than $2 million in cash has been announced by Dorothy K. Winston & Co. The Gateway Green industrial site is just north of the airport on Rte. 625, west of Rte. 28.

Montgomery College reports that 29-year-old Judy Stark is well into a carer as a house restorer in the Capitol Hill area. After some bad experiences as an investor in a house that had to be redone through subcontractors, Stark took a MC course in construction mangement from Abe Sind, a former home builder. Now the Nashville native leases two E. Capitol Street apartment buildings that she bought and remodeled. She also converted a former pool hall into office space and then into a karate studio.

SHORTLY -- Kathy and Cynthia Peck, who help their mother (Katherine Peck) run Hugh T. Peck Properties, are certified scuba divers. The Kensington-based firm founded by the late Hugh T. Peck recently purchased the 10 Northern Virginia offices of Carriage House Realtors . . . . The Suburban Maryland Home Builders Association, headed this year by Robert L. Mitchell, has promised to back legislation for both Prince George's and Montgomery counties to require every new housing unit to be under warranty . . . . Panorama Real Estate will combine a Claire Dratch fashion show with the showing of some expensive houses Sunday afternoon in the Potomac area. The public is invited to the River's Edge and Country Classic sites five miles west of Potomac Village on River Road . . . . The Northern Virginia Realtor firm headed by John B. Calio has published a 112-page cookbook that is being distributed to clients and friends. The book includes Joan Mondale's pumpkin bread recipe and a cheese ring formula from Rosalyn Carter. To this aficiando of rice pudding, Jermaine (wife of Sen. Warren) Magnusons's formula looks particularly tasty because she didn't forget the sine qua non, raisins.