Jenny and Myron Brilliant's house is the kind of place that makes real-estate agents launch into a frenzy of exclamation points: Curb appeal galore! Huge kitchen! Opportunity for expansion!

It's all true. Tucked away on a quiet street near the corner of Bradley Boulevard and Wisconsin Avenue in Chevy Chase, this turn-of-the-century farmhouse stands out amid a sea of 1920s and '30s Tudors and center-hall colonials. The shady front porch practically begs you to doze away a summer afternoon. Step inside, and a pentagon-shaped living room and arched doorways announce that this house has character — enough to last through the turning of two centuries.

Like any centenarian, however, the house has its pains. When the Brilliants bought the house five years ago, they discovered the plumbing was jerry-rigged, lead-based paint covered the front porch and the chimney contained carbon monoxide. "We think the only reason the previous owners didn't die from carbon monoxide poisoning is because there isn't any insulation," says Jenny.

Nevertheless, they fell in love with it. Jenny, who trained at a Manhattan art school before becoming a graphic designer, sighed over the wraparound porch, while Myron loved the easy walk to the Bethesda Metro station. At the time, the house also seemed like a good size: three small bedrooms and a bathroom upstairs, and a living room, dining room, kitchen, family room, study and bathroom on the main level.

It was the perfect space for Jenny, Myron, their young son, Andrew, and their daughter, Liza, who arrived shortly after they moved in. Then, about two years ago, Jenny and Myron began talking about having a third child. Jenny, who will be the first to tell you that she lives in the moment, said, "Why not?" Myron, who earned a law degree before taking a job at the Chamber of Commerce, tends to be more practical. (When he asked Jenny to marry him, he suggested she choose her engagement ring to make sure she got the one she really wanted.) Although Myron wrestled with doubts about whether they had the money and space for another baby, his emotions won out. Just over a year ago, baby Eric arrived. And, suddenly, the house that had been such a perfect fit was too small.

One tiny upstairs bathroom for five people? It seemed positively claustrophobic. And what about the toys that seemed to procreate every time Jenny turned her back? Wouldn't it be fantastic to have a separate playroom? And imagine a bedroom and bath for guests.

So Jenny and Myron began dreaming: They'd add a master bedroom and bathroom, tear down walls, and replace the old kitchen, family room, bathroom and screened-in porch. The architecture of their old house would be preserved, but inside, Jenny saw gleaming wood floors replacing the tired kitchen linoleum. As for that upstairs bathroom with its temperamental plumbing and ancient fixtures, "I just want to napalm it," she sighs.

The first thing to do was consult an architect, and Jenny knew just the man: Jim Rill of Rill & Decker Architects in Bethesda. She'd been so impressed by photographs of his work in the Washington Post Magazine that she'd remembered his name. He seemed to respect old homes, and examples of his work could be seen all over Washington, Northern Virginia and Maryland. The additions he designed enhanced but did not overwhelm the original structures.

Myron, who couldn't care less about details like pewter cabinet handles versus brushed nickel, sized up Rill: Here was a guy who wore sneakers to work, tossed around phrases like "busted our butts," and looked like an offensive lineman (which he was, 25 years ago, at Dartmouth College). Myron knew he could work with Rill.

When he undertakes a new project, Rill feels confident about the design process — but less certain about the personalities he'll face. "Every client is different," he says. Some couples get into fights in front of him (which he tries to defuse by telling them he'll charge double if he has to act as a marriage counselor). Other clients need hand-holding, like the woman who called him, terribly upset, to complain that contractors were using concrete in her home and she hated concrete ("It's just the foundation," he reassured her).

Rill felt the Brilliants would be good clients, in part because their personalities provide checks and balances for one another. "Myron is very financially savvy and concerned, and Jenny is more artistic and wants it done right," Rill says. "If he were left alone, it probably wouldn't look as nice. If she were left alone, it would go over budget. They're a good team."

During this past spring and summer, Rill and one of his designers, Kay Kim, began to capture on paper a vision for the Brilliants' home. This was the heady phase of the project, a time to erase every problem the old house contained, and create something the Brilliants could live in for decades.

Yet, even as they enthused over Rill's ideas, the first doubts began to creep into the Brilliants' minds. How, with three small children, would they live without a kitchen? They could move to a hotel during construction, but wouldn't that be awfully expensive? If they didn't move out, they'd have to put up with contractors coming in at all hours, making noises and messes.

And speaking of costs, exactly how much was this addition going to be? At first, the Brilliants thought it might cost around $250,000 — a supposition they now laugh at, in the way newer residents of Bethesda might laugh at their original expectations of home prices in this area. After meeting Rill, the Brilliants resigned themselves to a price tag of closer to $500,000. Jenny knew those numbers worried Myron. She was less concerned; after all, they had a lot of equity in the house.

When they bought it in 1999, they paid (newer Bethesda residents, brace yourselves) $360,000, then spent another $100,000 on repairs. The house was recently appraised at $800,000, and would probably sell for a good bit more. Expanding their home would be an excellent investment. Besides, how could they ever move? Their kids play outside with friends every evening, they meet neighbors at the community swimming pool and Myron coaches their son's Little League team. They've laid down roots.

Nevertheless, Jenny found herself driving to open houses this summer, imagining how easy it would be to move into a big new house. Myron noted that they had estimated a cost of about $10,000 for the first phase of the project, but they'd already spent closer to $12,500. If they were over budget now, what would happen when the project really started?

Meanwhile, Rill had concerns of his own. Construction prices were soaring, as were costs of materials like metal. Rill never cut corners by using untested contractors who might, as he joked, hire "a few guys hanging outside the Duron paint store with a mop." He knew the two contractors bidding on the Brilliants' house would do the job right — but would their prices kill the project?

On a steamy Thursday morning in July, Rill sits in his office on Wilson Lane in Bethesda. It is bid day — contractors' prices are in. Choosing which contractor to hire will come later — should they decide to go ahead — but whomever they go with, the news isn't great. With appliances and Rill's 15 percent fee, the grand total would be about $600,000. He picks up the phone and dials the Brilliants' number.

If the Brilliants agree to the project, they will, in essence, form a company with themselves as the board of directors. During the next year, they will face unknown stresses — many of which will fall on the shoulders of Jenny. Because Myron travels extensively for his job while Jenny is a stay-at-home mom, she will be the one to supervise the project, dealing with contractors and coordinating millions of details.

A few hours later, Jenny and Myron sit at their dining room table. Suddenly, it's Myron who is confident and Jenny who is anxious. It always happens like this: Myron gets his worrying out of his way early while Jenny dreams. Then when reality hits, he's prepared while she panics. "I don't have sticker shock," he says. "We're going to do it."

Jenny, still visibly nervous, nods her head.