In the house that Don Alexander Hawkins built in Cabin John, things are not always what they seem.

There are windows that look like doors, walls that aren't really walls and a fireplace that seems to be outside. Nestled in a wooded cul-de-sac, Hawkin's house is a combination of modern beauty, efficiency and illusion.

"It's a deliberate attempt to keep you from understanding what's going on," says Hawkins of the house that was his architectural debut.

When a freelance writer asked Hawkins to design the house 10 years ago, the architect was confronted with the twin challenge of meeting the physical requirements of the owner, who is confined to a wheelchair, and making it esthetically pleasing.

"He (the owner) wanted a small house and one of his main criteria was it should not look like a house designed for someone in a wheelchair," said the 40-year-old architect, a partner in the Washington firm of Hawkins and Bruner.

After rejecting an earlier set of plans drawn up by another architect, the writer (who asked not be identified in this story) and Hawkins worked on the project together. In less than a year the house was finished.

"The designing came fairly rapidly," Hawkins recalled, "because the number of rooms are very low . . . He accepted the basic design pretty quickly."

That design is deceptively simple. From the outside the house looks squat and rectangular. A driveway seems to lead into it, becoming part of a front porch recessed into the facade. Silver cedar siding gives the exterior a vaguely rustic look.

"He (Hawkins) managed to design a house that did not scare the builders," said the owner, who used to work as an administrative assistant on Capitol Hill. "Builders are scared by any house that isn't rectangular." Hawkins calls his design a "rectangle with notches in it."

The interior is a dramatic contrast to what the exterior suggests. High angled ceilings and the absence of hallways give this small, five-room house the illusion of great space. Navajo rugs accent the plaster walls and stained oak floors. There are a total of 27 corners in the house and none of the rooms are square.

Floor-to-ceiling glass fills the southwest corner of the living room and bedroom, affording an unobstructed view of Cabin John Regional Park.

"The owner wanted to be able to sit in the sum as much of the day as he could," Hawkins said, adding, "The idea of continuous openings from floor to ceiling was something I was interested in."

The owner describes the interior configuration as a "cube suspended in a rectangle." The cube is the dining "room," which is the focal point of the house and the rectangle is the perimeter of the house itself. The other rooms radiate from the dining area.

Two low walls (about 42 inches high) set the dining area apart from the rest of the house. "The low wall is there partly to obscure the difference in levels," Hawkins said. "It destroys the normal perspective lines." The split-level effect is achieved by a built-in ramp leading from the front of the house, past the dining area and into the living room in the rear. "Even though the ramp is only eight inches off the ground," Hawkins said, "it's a substantial change in elevation for someone at the 42-inch level."

In designing a house for a physically handicapped person, Hawkins not only had to include the obvious convienences, like wider doorways (36 inches instead of the standard 30-inch width), larger bathrooms and reachable closets and cabinets, but was faced with the more difficult problem of making the spatial relationships within the house interesting to someone who is almost always sitting down.

"As an architect, I looked to make it something more than just a house that works," he said. "The owner wanted it to be for people in general, not just people with limitations."

Like the ramp, the unconventional ceilings were designed from the point of view of a wheelchair. Hawkins calls his roof an "upside-down Mansard," flat on the outside and pitched on the inside. Ceilings are seven feet high at the center, rising to eight feet at the outer edges.

"From his vantage point, an eight-foot ceiling is very high so if I brought it down very low in the center it would be enough for him to experience a change in height," the architect said.

Hawkins seems to delight in incorporating subtle visual tricks into his design. "I like the idea of being able to see inside and outside," he said. "If you stand in the front, you look in, out, and then in again. Somewhere along the line it's easy to lose track of what's inside and what's outside.

"It's the same with the fireplace - it seems to be sitting outside." The brick fireplace is set away from the house by six inches and is bordered by full-length glass on either side, a constant source of indirect lighting during the day.

Some of the other innovations specifically for a handicapped person are windows that look like doors. This is to make easier to open. "I've had people try to squeeze through them." says the owner.

There is at least one exit from every room in the house in case of fire and the doors are flush to the floor. But modifications were kept to a minimum because the owner admits he was conscious of not interfering with the re-sale value of the house.

"The specific needs of a wheelchair are not that great." he says, "Designing for the handicapped means designing for everybody."