WASHINGTON WOMEN in Architecture, as a part of the National Women's Caucus for Art annual conference, has organized an exhibit of 15 projects by Washington architects who are also women. The show of photographs and drawings, organized by Barbara L. Mistrik, is open through Feb. 9 at the American Institute of Architects headquarters building, 1799 New York Ave. NW.

Ann Ardery's "house for an intersection" was an award winner in a competition sponsored by Japan Architect magazine. The Federal Center Plaza here by Sara Elizabeth Caples and Linda Spottswood of Hellmuth, Obata & Kassabaum (in a joing venture) is a $60-million mixed-use development.The Holy Cross Hospital addition in Silver Spring is by Karen Fox of Faulkner, Fryer & Vanderpool. The Oberlin College Snack Bar remodeling project is by Pamela Heyne. A prototype Standard Federal Savings & Loan Branch Bank was designed by Lelia E. Imas of Imas Gruner and Associates.

Andrews Air Force Base Personnel Center is the work of Kay Layne of Chapman, Miller & Layne. A gazebo for a Cleveland Park house is by Ann McCutcheon Lewis. A "space for social systems" -- laboratory prototype for the National Institutes of Health -- was designed by Pamela Clayton and Elizabeth Macklin. An art school for Chapel Hill, N.C., was a student project by Anita Marie Picozzi. A day-care center for children with special problems is a design proposal by Marcia Rascoe. Hamilton Park Site Improvements in Jersey City, N.J., was done by Patricia Schiffelbein with Oppenheimer, Brady & Vogelstein. A hotel for Charlottesville, Va., was a student project of Patricia E. Suplee. A State Compensation Insurance Fund Home Office Building in San Francisco is a design by Jacqueline Stavi of John Carl Warnecke & Associates.

Two other projects are described in stories on this page -- Katherine D. Blair at right and Deborah Libby Chemers below.

FOR A NEW homeowner, there's not much to beat having an architect for a sister. For a new architect, having a client for a brother may even be better.

Such were the happy circumstances for Deborah Libby Chemers, her brother Daniel R. Chemers and his wife Betty. The house addition was such a success that the Chemers not only are still speaking but also are congratulating each other.

Betty and Daniel Chemers are the sort of pelple who do everything in the right order. First they saved their money. Then they took a year off and went around the world. They came back with bundles of handsome rugs and boxes of exotic art objects. Then they bought and remodeled the house and had the baby. Architect Chemers, at the time of the project, was working in Philadelphia, where she earned her master's degree from the University of Pennsylvania. She and her husband, a veterinarian, have since moved to Washington.

The house is a pleasant frame structure in the Chevy Chase section of Washington. The previous owners had made many improvements, including a pleasant deck at the back and the beginnings of a new kitchen.

The Chemers wanted a downstairs powder room. They needed a den where both of them could work at home. He's lawyer and she's special assistant to the director of the National Institute of Law Enforcement. Upstairs they had grandiose ideas about a master bath, more closets and a bigger bedroom.

Architect Chemers took a look at the house and at the zoning regulations for the street. It was obvious that the only available space had to come from the tiny front porch. So the porch was removed and a two-story, 8-by-22-foot addition built.

The most dramatic part of the project is the master bedroom. A bank of slanted windows runs 20-odd feet the depth of the room. Underneath the windows are a matching bank of clothes closets with a slanted top -- mirrored , so the effect of the clerestory windows is doubled, making the whole thing into a triangular skylight. Mirrored doors on the closet echo the reflected light. Track lighting at night substitutes for the sun. This dressing area is raised a step above the bedroom, with heating built in underneath.

"The room is always brilliantly lighted," said Betty Chemers, "no matter what the weather."

The rest of the room looks good as well. There's a bookcase and a built-in divider which has storage below and an art niche above. The ceiling is dropped to seven feet over the bed to hold lighting and some of the new beams. The effect also helps give the bed section a more intimate quality.

The master bath is walled with Formica, banded with a stainless steel strip.

The second upstairs bath was enlarged and spruced up as well.

In the living room, the new walls on either side of the rather high fireplace were set at an angle, providing wood storage in a drawer that rolls out. Atop the storage is a padded bench. A tall shelf supports the stereo speakers. The effect is like an inglenook. A splendid coffee table by Pennsylvania sculptor Nakashima is on its way. With the Chemers' rugs, burght on their travels, the effect should be warm and handsome.

Around the corner, a small hall separates the bath from the living room and the den. The den has a shelf for a typewriter. The handsome cabinets, top and bottom, are actually kitchen cabinets. Since overhead kitchen cabinets are narrower (17 inches), they were used top and bottom to save space. The sofa opens to accommodate an overnight guest.

"We call it Hawky's room," said Betty Chemers. "Hawky is Emma Hawkins, Annie's babysitter." Annie is only 2 years old but she's already talking up a storm.

The Chemers were, as they said, pleased as punch with the addition. They liked Mills Floors, who sanded and refinished the wood floors, and Benjamin Gibbs, the mason.

But not all their experiences were smooth. Not enought tiles came in the order for the kitchen.The curtains were cut too short. The rug for the dining room was too big. "I came up to the house just as the carpet for the den arrived," said Debbie Chemers, "and said, 'Hey there, it's too light-colored.'" The sofa from Scan was the only thing that really arrived on time; the lamp is six weeks late. The dining room set dur in January is now supposed to come in June.

"It's us against them," said Betty Chemers.

A new tool shed, raised wood planter boxes and a side fence completed the job. Landscaping is waiting for the spring.

The Chemers family figures it all cost between $40,000 and $45,000, not counting all the furnishings. They turned down a higher bid from a wellknown professional to take a lower bid from a less-experienced contractor. Neither they nor the new contractor are sure that was a good idea.

Now Betty, Dan and Annie have their house -- and Deborah Chemers has a raft of new architecture clients in the neighborhood.