Betsy Starnowsky is facing a problem most of us who have decorated a home know well.

Think of it as her First Law of Redecorating: There's always a good reason the last owner did something seemingly stupid.

In this case, it was putting down ugly vinyl flooring in a bathroom. Starnowsky has pulled it up so she can show off the original tile, only to find that she's exposed an enormous crack. And, after repeated scrubbings, the tile won't come as clean as she'd like.

It's somehow comforting that even an interior designer doing a glamorous show house room has to deal with such things. Starnowsky is one of 26 professionals selected to headline this year's Baltimore Symphony Associates Decorators' Show House. If you ever thought show houses came together without a glitch and without much elbow grease, her experience will disabuse you of that notion.

The bathroom is off the bedroom Starnowsky signed on to redecorate. It's called the Mamie Eisenhower room, so named because the president and his wife were guests of the owners and this was her room when they visited. The tiny bathroom came along with it, and one reason the designer chose this room was that its bathroom seemed to be in better shape than the others. Unfortunately, she says ruefully, "The biggest challenge has turned out to be the bathroom."

Tell us something we homeowners don't already know.

Any room that needs a plumber, an electrician, a wallpaper hanger and a painter -- the definition of a bathroom -- is potential trouble. For instance, the new toilet that matches the new pedestal sink arrives with a broken flange and has to be replaced. Luckily the owner is paying for the new fixtures; and the toilet isn't a special order, which would take time the designer no longer has.

Not only that, there's a pane missing in the window. It was there just a few days ago. The exterior painters must have knocked it out, she decides. (They agree to replace it.)

Starnowsky solves the bathroom tile problem the way many of us do. She cleans the floor as best she can -- going over it several times -- and adds two attractive white bathroom rugs to hide the crack. After all, she says, "I know people are only going to spend two seconds looking at the bathroom."

It's like the exposed pipes in the otherwise charming bedroom, which run along the wall near the ceiling. You could call this Starnowsky's Second Law of Redecorating: Some things you can't fix. Get over it.

"I'm just going to ignore them," she says.

Well, not quite. Her assistant has painted the pipes and the bit of wood trim behind them a pretty sage green, so that the exposed pipes blend into the wall. The color will, the designer believes, pick up the green in the flowery wallpaper. However, we all know the Third Law of Redecorating: No color that ever came out of a paint can looks like the sample.

"The green came up sagier than I had hoped," she admits. "But once the furniture and draperies are in, it won't be noticeable. I hope."

This is all happening at crunch time, the week in mid-August when the myriad details that make up a spectacular show house room start coming together. Must come together, because Moving In Day for furniture is the next Monday.

Months in the making

The process started in April. Interested designers were invited to tour the empty mansion in Owings Mills, which was once the palatial home of Gen. Douglas MacArthur and then for many years a nursing home.

The house overlooks 19 acres of land in Greenspring Valley and has 32 rooms. It was built for Henriette Louise Cromwell Brooks; after she married MacArthur in 1921, they lived there for over a decade. The general named the house Rainbow Hill in honor of his Rainbow Division in World War I.

Each designer was supposed to bid on three rooms; they then had a week to make up proposals and design boards showing fabrics and colors.

"First we measure the room to scale and see how everything fits," Starnowsky says. "Then we start researching and get a concept in mind. Then we go searching for pieces."

Her concept for the room is true to the period, a room Mrs. Eisenhower would have been quite comfortable in, with antique reproductions and coordinated wallpaper and fabrics in pinks and greens. The climbing roses on the walls are big -- "big room, big scale," she explains. "It's all about scale." (The Fourth Law of Redecorating.)

"In the back of my mind I kept thinking about my grandmother's house. I wanted it to be fresh but very traditional."

Starnowsky's search for furnishings was easier for her than for many designers because the 45-year-old is president of Maidstone Interiors in Hagers-town, and can use items from her own showroom. Family members own Statton Furniture Co., also of Hagerstown, so she can get furniture on loan from them.

Still, by participating in the show house, Starnowsky expects to have about $8,000 in out-of-pocket expenses, even with the discounts tradespeople give her to be mentioned in the program. This is her fourth year with the Baltimore Symphony show house; altogether she's participated in a dozen or so different ones in the area.

"Between the clientele we pick up and the furniture [and accessories] we sell, we may break even," she says. "It's hard to put a price on the exposure. And a lot of it is the self-satisfaction. Here you can really show off what you can do as a designer. When you're working for a client, there are always stipulations."

'Ecstatic' effort

Early in May the designers were notified which room, if any, they had been given. Betsy Starnowsky's first choice, the grand foyer, went to another decorator; but the bedroom, with its curving bay and large windows, had plenty of potential.

The most frantic part of the process -- writing up the special orders for everything from draperies to upholstery to the canopied bed -- began almost immediately.

"The custom work is the most time-consuming," she says, "getting the work in progress."

These orders typically take six to eight weeks to be filled, so if they aren't put in quickly the love seat with just the right flower print or the finished-to-order bed won't arrive in time.

Then it's hurry up and wait.

"The hardest thing is to get people in to get the job done," says Starnowsky, as she waits for paper hangers and plumbers. (Surely the Fifth Law of Redecorating?) "I have some pull, but then I have to wait in line like everybody else."

The life of an interior designer may seem glamorous until you see Starnowsky on her hands and knees scrubbing out a 50-year-old bathtub (the only fixture not replaced in the bathroom). Or cleaning the original brass and crystal chandelier by hand. Or spending hours inventorying and putting a number on every item for sale in the room, from the Asian prints in the faux bamboo frames to the antique book on the coffee table. Or dealing with details like installing a new brass doorknob she's aged with vinegar. She even picked up the soft green hand towels herself at Bed Bath & Beyond.

Rainbow Hill is the most difficult show house she's worked on, Starnowsky says, because the homeowner is having the exterior painted, carpeting pulled up everywhere, and floors refinished while designers are trying to meet their deadlines. For several days the stairs are closed off to be repainted, and Moving In Day has had to be rescheduled.

"I was trying to paint the door while they were sanding the floors in the hall," Starnowsky says. She was told she might have to bring in the carpet installers through the second-floor window; it was easier to schedule them for a later date.

There is, of course, always one last-minute thing that goes wrong. And surely that's the final Law of Redecorat-ing. In this case, the last screw that held up the bed's canopy wouldn't go in right, and one had to be brought from Hagerstown the next day.

When the bedroom is finally completed, it's enticingly feminine, with flowery wallpaper from F. Schumacher & Co. and coordinating draperies and bedspread. The soft green carpeting adds to the garden feel, and a breeze drifts in from three tall windows. The dark traditional furniture, including the solid cherry bed, gives weight to the room. In the bay is a sitting area with a flowered love seat and two tufted-back parlor chairs in coral.

"I went a little stronger than the color in the wallpaper to give it a little punch," says the designer. "There's so much green in the room."

Looking back over the project, Starnowsky sounds almost surprised to find herself saying, "It all went fairly smoothly." (Well, that's one definition of smooth.) "It's one of the nicest rooms we've ever had. I'm ecstatic."

Show house

What: Baltimore SymphonyAssociates Decorators' Show House, Rainbow Hill

Where: 10729 Park Heights Ave., Owings Mills

Hours: Today through Sept. 21, Sundays noon-5 p.m., Tuesdays and Thursdays 10 a.m.-8 p.m., Wednesdays, Fridays and Saturdays 10 a.m.-5 p.m.

Tickets: $15 off site (BSO ticket office: 410-783-8000 or www. baltimoresymphony.org / showhouse), $20 at the door

Directions: Take Baltimore Beltway to Exit 21, Park Heights Avenue north. Cross over Greenspring Valley Road. The show house is on the right.