When Loudoun County bought a small, white frame house 16 years ago and turned it into a center for mentally ill residents, the 1,800 square feet of space on Davis Avenue in Leesburg seemed a palace.

Today, what seemed like a palace seems more like a doll house. With a dozen staff members and 250 clients who visit at various times, Friendship House has been forced, for sheer lack of space, to put 50 mentally ill residents on a waiting list for services.

Loudoun County's estimated 900 mentally ill residents may be a largely unheralded segment of its population, says Friendship House supervisor Shirley Thomas, but their number has grown along with the county.

This week, the county took steps to accommodate that growth. It began construction on a new Friendship House that will be about five times as large as the present building. The new structure, which will cost about $573,000, is being funded by the county's Capital Improvements Program.

"It's going to make a tremendous difference for the {mentally ill} patient population," said Anna Robbins, a Sterling resident who helped found the Virginia and Loudoun chapters of the advocacy group Alliance for the Mentally Ill. "The building they have is way, way too small. They've got a waiting list" that is unacceptable, she said.

"We're excited . . . . I hardly need say this," said Judy Heinz, who heads the county's Community Services Board, the policy-making body for mental health and mental retardation services. "Having 35 people squeezed in that house creates stress for both the {clients} and the staff."

Clients at Friendship House usually are referred by a doctor or a mental health professional, but their attendance is strictly voluntary. Fees are covered by Medicaid and some insurance companies. Clients or their families cover some costs if they can afford it.

The new building, to be completed in about a year, will be on Meadowview Court, near Leesburg Airport. It will be between the county's youth shelter and a transitional shelter for the homeless that has not yet opened.

The building also will be a boon to the Alliance for the Mentally Ill, which meets at the present Friendship House on Tuesday nights. Sometimes, Robbins said, there are 15 family members or friends of mentally ill residents. But other times there are 50, which means the little house is filled to overflowing.

With more space, the Alliance for the Mentally Ill hopes to meet more often and in more specialized groups, Robbins said.

"Hopefully, we can provide the people with different groups, such as those who have young children, or those who have just learned that their loved one has a mental illness," she said.

Both Robbins and Heinz have family members who are mentally ill but who are leading independent lives after getting help from programs such as those offered by Friendship House.

Friendship House helps mentally ill residents learn basic skills, such as housekeeping, "things you and I take for granted," Thomas said. It places some residents, 21 at last count, in full- or part-time jobs. David Lambelet, an employment specialist with the county's Department of Mental Health and Mental Retardation, says he expects that number to increase once the new building opens and residents on the waiting list receive services.

Perhaps most important, Thomas said, Friendship House shows its clients, most of whom have been hospitalized and are trying to begin new lives in the community, that they are not alone.

"Once they understand their illness, once they understand that other people have it, once they make some friends here, they are able to begin to cope," Thomas said.