THE BUILDING inspector looked at the new roof and said, "Say, your bleachers are too far from the tennis court to see good."

After delivering himself of this bon mot, he made the worried remodelers sign a letter absolving the county of any responsibility if the roof fell in.

Indeed, Jonathan and Patsy Titus' newly remodeled house does have a roof with a vague resemblence to bleacher tiers. It isn't for sitting on, though. The stepped protrusions neatly serve to package all the new as well as the old works - air conditioning ducts, drain pipes, vent stacks, skylights, chimneys and old and new varying roof lines. The sum of the parts makes for quite a number.

In the beginning, the addition was to be a small alcove to hold the grand piano.

Some $120,000 later, Jonathan and Patsy Titus have a magnificent living room with a stage for the piano complete with an audience pit. They also have new decks, new two-story master bedroom and tower, an enlarged kitchen, many new skylights and window walls, a new breezeway and garage.

Most of all the entire house has been gift-wrapped with a dashing new cypress cover. The new exterior changes what was a humdrum 1952 one-story brick house into a wood sculpture decidedly dated 1978. The totally new space amounts to 1,800 square feet. Another 1,000 has been totally reworked. And the new decks add another 1,200.The house now is a large 6,500 square feet - one story and full basement. There are now three bedrooms and two dens upstairs and three bedrooms and a poolroom below.

They removed 100 truckloads of debris (at $10 to $15 a square foot for all demolished areas).

The Titus family - parents, three sons (Adam, 16; Matt; 15; Jason, 8) and a maid - lived in the middle of the house white the rest was rebuilt around them.They did a great deal of the work and all the contracting themselves - and lived to tell the tale.

The family loves the seven-acre site of their house on a rolling hill in Northern Virginia. They bought it six years ago for about $80,000 - a bargain even then. The site gives them plenty of room for a tennis court and a swimming pond with five-pound bass. One son has a horse and another practices for his driver's license on the long drive.

The only trouble with it all was that no one had planned on the piano. Patty Titus, her friends say, had once aspired to be a concert pianist, and the great 6 1/2-foot Bosendorfer, a prize among pianos, was the gift of a grandmother. But Titus left the piano behind with her mother in California and went on to be an executive director of The Therapy Center in Alexandria. She hadn't played a piano in 17 years. When her mother moved to a smaller house, she wrote to say, "Send for the piano."

When it arrived, it was obvious that it would't fit. So Jonathan Titus, an internist, called Joseph Boggs, a young architect who was also a patient. Boggs (who now has an architectural studio with Dewberry, Nealon and Davis) had earlier designed some bookcases that the doctor had built. He began a long series of conferences with the Titus family, spending nine months on the design before going off to the Harvard Graduate School of Design. James Madison Cutts did the structural engineering, which included, Boggs said, "some pretty fancy stuff." The lighting consultant was Peter Barna with Edison Price fixtures.

Boggs thinks the Tituses are excellent clients. "The design is really a radical one. I like to think it's in the post-modern idiom. It's remarkable to find clients who are willing to take a chance on an unknown architect and an advanced design, all at once."

"I don't think I would've bought Joe's idea," said Patsy Titus, "if he hadn't made the model." The model, an elaborate cardboard affair, showed just how the fancy roof worked. The Tituses also went to see Boggs' father's house in Richmond, which incorporates some of the same design ideas.

Jonathan Titus had an advantage over some in understanding how it all would come together. He had worked during high school doing every kind of building trade job. He put himself through medical school as a Buick mechanic. Recently he diagnosed the trouble with Boggs' Jaguar with his stethoscope.

"I knew from the beginning that I wanted to general contract the house myself. I never even thought of putting it out to bids. I knew they'd all be too scared of it," Titus said.

He ran off a number of professional carpenters. "But Tom Taylor was a lifesaver. He did all sorts of work from carpentry to painting. He made it all work. His family even came to help him hoist some of the framing on the high windows. The rest of the help was mostly kids out of school and a steamfitter. They were great because they didn't have any preconceived notion about curving walls for instance."

One professional dry-wall man dashed up to Titus and Boggs and said in a tone composed of equal measures of horror and disbelief: "This wall is 8-foot-4-inches. Don't you know dry wall panels are 8 feet?"

Others took things more calmly: Griffin Plumbing; S & S Kitchens of Manassas, who did the custom cabinets; and the unnamed backhoe operator who managed to dig an interlocking trench with as much precision as a clockmaker.

One of the best of the several long-suffering friends who pitched in was Stan Scheyer, chairman of the board of Family Health Care of Maryland. He became so fascinated with the process, he hired architect Boggs to design a house for him.

There were many times when Titus and Boggs would come home to find the workers had hit something they didn't know how to do and had put down their tools and gone off to the nearest beer joint. There they'd sit, heads in hand until someone came to fetch them back. "We must've made that beer joint owner's business," Titus said. Titus and Boggs ate lunch together every other day. Boggs came to the project six and seven days a week.

The worst time came when Taylor called Titus' office and said, "I think you'd better come." "When I got out here, I found two young workers soaking their concrete-covered feet and legs in the pond. The kids, not knowing what they were doing, had waded into the cement for the foundation, to mix it with their sneaker-shod feet. One boy in particular had bad cement burns." The doc patched them all up and work went on a few days later.

The other injuries were to Taylor's little girl, who hurt her chin on a lag bolt, and Jason, who took a wrong step and cut his head on a concrete wall. Titus sewed up the wound on the kitchen table.

Another time the subcontractors didn't show up for work for four days. "Didn't say a word of apology when they came back. When I jumped them about it," said Titus, "they said with an air of surprise, 'Didn't you know it's duck hunting season? Nobody works during the duck season.'"

One night, when half the roof was off and covered only with builder's plastic, a driving rainstorm came up. The Tituses, with the Boggses, were at the Kennedy Center. They raced home to pile on more plywood and plastic. In general they tried to take only 10 feet of roof off at a time, making temporary roofing of plywood and plastic.

One of the problems was that the old house had been constructed by builder Gladstone Butler as a fortress. The heavy masonry walls ate up drill bits as though they were candycane. Even the clay soil around the house was as hard as if it had been baked into adobe.

The cypress was also a problem. The price went up overnight. Finally, on the telephone, they found 2,000 board feet in Florida and bought it sight unseen. It t came on two tractor trailers and all had to be stacked, 15 feet high, in the new living room. "I came in and looked at it and died. I yelled, 'Joe, the room is far too small. We've made a fatal mistake,'" said Titus. Today, the room seems vast.

And then there was the day when they ordered 300 tons of crushed gravel. Eleven dump trucks arrived at their road at once - all yelling "I was first." Titus found that the truck drivers were paid by the load, so the quicker they could dump the richer they were, the longer it took them to dump the madder they were.

Now, two years later, even the grass is in, and the Tituses bask in their skylights. The living room, according to Patsy Titus, makes the Bosendorfer sound "much better than it did at home, when I would play 'Malaguena' as a duet and everybody would leave." A curving wall behind the piano and a slanted floor in front give emphasis.

The ceiling over the stage is normal height, but the ceiling over the conversation pit, a step or two down, is about 16 feet high. When there are crowds, everyone sits on the steps and the edge of the stage. There's a double-glazed skylight just above the piano for drama. Sliding glass doors lead onto the deck overlooking the pond.

The dining room, where the old living room once was, still has the fireplace and the bookcases. The old dining room works much better as a breakfast room, especially with the huge new skylight. The kitchen has been enlarged with the help of the old breezeway. A pleasant deck adjacent to the kitchen and breakfast room also faces the pond.

The master bedroom (formerly the garage) is especially luxurious, with another 16-foot ceiling. A spiral staircase leads to a tiny retreat with a deck off it. "A great place if one person wants to read and other doesn't," said Jonathan Titus. The room is furnished with the family's Victorian antiques.

Adam's bedroom now adjoins the new breezeway (with storage wall) and garage, with an outside door for a quick getaway.

And what would they change if they had it to do over again? "I'd use 10-penny nails on the deck instead of 8-penny nails," said Titus.