Joan Slous from New York City where people don't build houses, they rent them. So when her husband, George Lanik, said he was going to design and build them a house - himself - she was, to put it mildly, surprised.

Lanik was sort of surprised himself. He really hadn't set out to build the house all by himself (except for the flooring, plumbing and foundation) - it just worked out that way. In the end, Lanik was his own real estate agent, architect, builder, carpenter, electrician, painter. Because no bank would give Lanik and Slous a construction loan, they financed the entire project from their credit unions, becoming, in effect, their own mortgage bankers.

They've been in their house since Nov. 1 (when Lanik took a five-week vacation from housework), and it not only hasn't fallen down yet, but shows every promise of being their dream house. The 1,900-square-foot house only cost $28,000 in a day when building costs are running four times that. What's more astounding, in this weather: Their total utility bill so far (they say, whispering so PEPCO won't hear) has been only $120 for two months. That in the worst two months for heating that everyone in these parts can remember.

He and Slous had found the lot by the expedient method of driving around town until they found a vacant one they liked - in the Northwest, two blocks from the Van Ness Metro and convenient for grocery shopping by cart. He knocked on the neighboring house and asked, "Could you please tell me who owns the lot next to you?" The householders, Murray and Daomi Strasberg (she write gothic and adventure novels) said they did, and yes, they would sell it, after they'd looked the couple over and decided Lanik and Slous would make good neighbors. The couple paid the $17,500 cash for the lot - which wiped out their savings.

The saving and loan association curled their lips when they asked for construction loans, even though the lot was paid for. One bank said it would give them a loan if they banked with them for six months - and then defaulted on the promise. Finally, the two went to their credit unions and managed to borrow, at interest rates from 9.6 to 10 per cent, the $21,000 they needed. They managed to acquire another $7,000 from their salaries and family loans. Now they are pretty smug about the whole thing, because the house will be COMPLETELY paid off in five years. Lanik is 33 and Slous 27, so they think it will be great to own their own paid-for home before they're 40.

Lanik and Slous weren't the first in the neighborhood, interestingly enough, to find a lot, design and build a house on their own. A few doors down Klauss Klatt and his wife had done the same 10 years ago. But Klatt had the advantage of a good architectural education and years of experience as a licenced architect.

Lanik hadn't even studied drawing since 9th grade. He works as a nuclear engineer and physicist with the U.S. Nuclear Regulatory Commission. "But I'm much more of a physicist than an engineer - I never studied mechanical drawing or construction, for instance."

On the other hand, his father built his family's house in Minnesota when Lanik was 10. "I really didn't realize how much of an impression that made on me. When I was working on the house, a great deal came back to me that I had learned helping my father."

He had planned to buy a standard plan, as his father had done, but he found that no lot is standard. Their, for instance, has a steep slope north. He read several books to educate himselp." Architecture, Residential Drawing and Design" by Cloise E. Kicklighter and "Modern Carpentry" by Willis H. Wager (both published by Good-heart-Wilcox Co. Inc.) and "Woodframe House Construction," Department of Agriculture Forest Service Handbook No. 73 (available from the Government Printing Office).

Then he drew his own set of plans for a five-level hillside house. It took at least six trips to the D.C. permit office - at an hour or two at a time - before he got them all approved. For one thing, he didn't realize at first that he could get away with minor changes without changing the permit. He actually made a number of design changes as he went along, and now he's sorry he didn't make a few more.

Then he hired (for $6,500) a contractor to build the foundation and pour the concrete floor. But a workman (since fired) got the wall crooked. And Klatt, the arcitect neighbor, came by to warn sliding down the hill. The concrete contractor tore out the bad work and redid it, and Lanik thinks it's there to stay.

That experience shook Lanik's belief in hiring allegedly experienced workmen, so that's when he admitted to himself that he rather do the rest himself.

He built the natural cedar walls ($4,500) complete with the windows placed in them, and then, helped by a friend, titled them in place. His wife, a lawyer with the Labor Department's Solicitor's Office, Occupational Safety and Health Division, couldn't bear to look. "I know he must have had dozens of code violations."

Once, when he lifted one wall in place, all guyed with ropes, a strong gale wind blew it over and onto the ground. "I was surprised it didn't think take the whole house with it," Lanik said. Another time a sudden March snow storm put 8 inches on the subflooring, crinkling it in one spot.

Lanik did all his own electrical work, taking a test at the permit off-ice. The house is full of double-throw, double-pull switches (the kind that can be turned on and off from different locations).

The heating plant is one of the most efficient on the market today: an electric air source heat pump with back-up resistant wiring. The heat pump extracts the heat from the air down to 28 or 30 degrees (on the same principal as a refrigerator). Below that, the pump has to have the help of regular electric heat. The Laniks' system uses air ducts to distribute the heat. In the summer the system reverses itself and cools instead, using the same principal of extracting the cool from the air down to a certain point.

Lanik designed the house to take advantage of what is called "passive" solar heat. There are banks of clerestory windows on the south side of the house, at a peak of the steeply sloping ceiling. The overhang is calculated so that sun comes into the house from Sept. 1 to April 15, but not at all during the late spring and summer. There are no windows at all on the east and west exposures - "I noticed all the neighbors keep their blinds drawn on the party lot line; besides east and west windows have too much summer heat gain," Lanik explained. There are windows on the north. All the windows are Thermopane, by Anderson Windows ($1,000). The house has about 12 inches of insulation in the ceiling and another 3 in the walls, but (some would say for shame) none in the foundation.

During the day, especially when the sun shines, the house stays quite comfortable with minimal help from the heating system. Lanik modified the heat pump so that the auxiliary heating can be manually controlled. In cold weather and on weekends they turn it on when they are home. At night, since both are heaty Northern types, they set the thermostat at 62.

The heat pump, a Carrier Corp. 19,000 BTU unit, cost $700, but the ductwork, from Sears, Roebuck and Co., came to another $600.

Eventually Lanik hopes to install solar panels to help with the heat. He put about 60 tons ($500) of gravel under the garage to use as a heat sink with the solar unit.

Lanik figures it took him about 1,000 to 1,200 hours of work. They beg an on Feb. 9, 1976, when they'd been married not quite a year, and moved in Nov. 1, 1976. He worked every night from 6-9 p.m. and every Saturday and Sunday. Slous swept up and brought supper to the site. The pair, plus her father, did all the painting in one weekend at the finale.

He was surprised to learn it was cheaper to have the flooring installed, at $1.40 a square foot than to buy the materials and do it himself. He laid the ceremic tile in the kitchen and foyer himself without any problems.

The house has a steep sloping ceiling going from the first floor living room to the dining/family room and kitchen, a sort of mezzanie on the upper floor. Below the street level are two bedrooms and bath. On the lower levels are a utility room and the furnace room. Eventually the lower level will be a family room a walk-out patio.

There are things they would change in the design of the house sliding glass doors and a deck on the back for instance, and perhaps sliding glass doors on the lower level. They'd like to have one of the heat-efficient wood stoves in the case of electricity goes off - for now they have to hope it won't.

"It certainly took me a lot longer than it would if I did it now - and I'm not even counting all those nights I stayed awake worrying about how I would do it," Lanik said. "But I believe this was the only way Joan and I could afford to have a house in the District where we wanted to live. We couldn't afford $80,000 for a house, or even the awful prices you pay for a shell. Besides, we wanted a contemporary house, and I'm convinced it took me less time to build this one from scratch than it would have to remodel a house."

But would he do it over again? "Well, when I get all the trim finished on this one, and the deck built and the solar heat in and the lanscaping done, I intend to try another one," he said.

His wife looked surprised.