While housing starts nationally are expected to decline this year from the level of nearly 2 million reached in 1977, a survey of 12 major home building firms here shows that they expect to begin 8,161 houses this year, an increase of 28 percent.

And in light of 1977's strong housing market, the area's smaller builders - who produce fewer than 100 houses each in a year - are also not expected to curtail production.

A forecast from the economics department of the National Association of Home Builders indicates that, area-wide, construction of about 30,000 houses will begin this year, up from 24,000 last year.

Ten of the 12 area firms surveyed by The Washington Post indicated that 1978 starts will exceed those in 1977. One large builder, Centex Homes of Washington, plans to more than double last year's total of 352 houses by building 850.

The survey also showed that the volume builders in this area are now led by Ryan Homes, which finished 996 houses here last year and expects to complete 1,350 this year. The Ryland Group, which also builds in varied locations, plans to build 1,100 houses, a significant increase over the 900 it finished in 1977. Washington Homes Inc., which competed 716 houses last year, will build 850 this year.

Ryan, Ryland, Washington Homes and Centex are all part of national home building firms. The Yeonas Co., a local company that is now a part of the Olin-American conglomerate, built 706 houses last year and is planning 745 this year. The 30-year-old Kettler Brothers company finished 601 houses last year and will build 664 in 1978.

The other major building firms contacted were Miller & Smith, Edw. R. Carr & Associates, Hylton Enterprises, MCD Enterprises, Watergate Developments, Inc. and Richmarr COnstruction Co. All built 300 houses or condominium apartments each last year and plan to build just as many or more this year.

Most of the builders contacted said they had raised prices from 8 to 15 per cent last year and planned to raise prices along the same lines this year.

While one builder said the higher cost of land would account for most of this year's price increases on his houses, the others said that added government regulation was the prime reason for house price increases, followed by the added costs of land, materials and labor.

The builders said they had substantial numbers of houses on which buyers had placed deposits but not settled. One builder said that production through the first half of 1978 is covered by contracts on which buyers have made sizable deposits.

What do builders fear most in 1978? Well, there has to be some reasonable concern about the likelihood of a continuing high demand for new housing - particularly in view of rising mortgage interest rates and the possibility that available funds for mortgages will be tighter in a few months.

"Mortgage interest rates seem to be headed to disasterville again," commented Larry Breneman, president of Washington Homes, which builds moderate-price houses at 28 locations here.

Edward R. Carr, who heads a Northern Virginia firm with a long history in new housing, said the firm plans to embark on a line of more expensive houses this year at two locations in the McLean area.He said prices will range up to $150,000.

"Greater-than-normal price increases may have a depressing effect on the market," he said, "but I believe the demand will continue at reasonable levels for at least the first half of the year."

Paul Yeonas of the Yeonas Co., Gordon Smith of Miller-Smith and Marvin Kay of Richmarr all said their firms are paying increased attention to energy-saving procedures this year to counteract the high cost of electric heating. Smith also noted that buyers are aware of the investment opportunities in new houses. He said: "We don't have to tell them - they know the pitch."

J. Kenneth Schwartz of Centex said that the increasing difficulty faced by young people wanting to buy houses has become "very disturbing." James Roberts of Watergate, which builds new condominium apartments and town houses, said that "costs are escalating at a very rapid pace that, if continued, will force selling prices up drastically."

John Walvius, vice president of Hylton Enterprises, said the firm is widening its product line to test the market for larger, $90,000-range houses in Dale City and also some new duplexes at the lower end of the market.

Meanwhile, the Labor Department reported recently that wholesale prices of lumber, plywood, concrete and gypsum products rose sharply in January, a month that also witnessed a 29 percent downturn in new housing starts nationally due to severe weather conditions. CAPTION: Picture 1, Centrex Homes is building 307 houses in its Langley Oaks sub division of McLean. These models sell for $160,000. By Larry Morris - The Washington Post; Picture 2, Yoenas Co. is building these houses near Wolf Trap at Rte. 7 in Fairfax. By Larry Morris - The Washington Post