Every weekend the army of house-hunters is out there, carrying newspapers with circles around the fine-print ads touting the amenities of this house or that condominium.

But in a market still reeling from high interest rates and high housing prices, fewer and fewer people can afford the $150,000 house or the $90,000 condominium, let alone the costs of utilities to keep the family bungalow heated and lighted.

So Northern Virginians, like almost everyone else, are exploring less conventional and still-new methods of putting a roof over the family head.

These include moving into "accessory" apartments within existing houses, finding houses to share through programs which put those in need of housing in touch with homeowners who have extra space, co-buying houses--some of which are being specifically designed to be shared by couples or singles--and finding an investor interested in helping with financing in return for a share of the equity.

For families with children, the search can be far more difficult. In some cases, they have to run a course of obstacles ranging from zoning laws to the current construction trend of building smaller houses to capitalize on the shrinking size of the family and the high number of singles in the area.

Local zoning officials say they are discovering an increasing number of violations of zoning regulations, which prohibit more than four unrelated adults or more than one family from living together in one unit in an area zoned for single-family dwellings. Such arrangements are violations in all of Northern Virginia but Falls Church.

And local officials say they also are finding, especially in apartment units, more people living together than is permitted by the health codes.

"We're coming across it about once a week," said Arlington community inspector Darrell Holman. "It's becoming more and more of a problem. A majority of it is people coming from overseas who don't know they can't do it. . . . But if you have two married couples in a house, whether there are children or not, it's illegal."

For many, sharing cramped quarters is the only way to find affordable housing. "Because of the economy today, the only thing they can do is try to get together to purchase or rent," said Falls Church zoning administrator David Rock. The City Council there had considered tightening regulations on the number of unrelated persons allowed to share housing, he said, but it rejected the idea. "They wanted to give people more freedom to solve the economic and social problems of today."

Sharing has "become more prevalent," he said. "The trend is here."

Doubling up is also an approach gaining favor among those in the market to buy.

The terms of shared ownership and equity may vary, but they usually involve a prospective home buyer who can't afford the required down payment and monthly mortgage payments for a house or condominium and an outside investor who is willing to subsidize part of the potential buyer's costs in exchange for a share of the equity.

The outside investor could be a relative, friend, stranger or even a corporation willing to lend money on innovative terms in anticipation of high returns. Typically, the investor agrees to put up half or more of the down payment and up to half of the monthly mortgage, tax and insurance costs. When the property is sold or refinanced, the investor usually gets substantial capital gains.

In the case of D. Meshell Brock and Sherry White, the two were friends who worked together at the Marine Corps headquarters in Arlington and shared an apartment. They decided in February to co-buy a $72,000 three-bedroom unit in Woodburn Village in Annandale.

Brock, 23, who is in a secretarial training program, owns 25 percent of the unit, and White, 30, a budget analyst, owns 75 percent. Together they share the mortgage payments and equity 75-25, and each takes her share of tax deductions.

While there is still a great demand for single-family detached homes, builders say, the cultural changes of the past decade have affected how new housing is being built and marketed.

"The demographics of the population to be served are certainly changing," said Joseph Hayden, spokesman for the Northern Virginia Board of Realtors. "Society is producing more singles and smaller families than years ago, and the real estate market to match the trend doesn't change that rapidly. We're talking bricks and mortar here.

"So there's bound to be a lag between the expressed demand for such housing and the character of the housing inventory that serves them. . . . The existing housing stock is being modified to meet the new requirements."

Tapping the singles and small-family market is a "natural" for developers in the Washington suburbs, said Morrie Sharlot, executive vice president of the Anden Group, builders of such complexes as Windgate West and Court Bridge, both in South Arlington.

Although the complexes were not specifically designed for the so-called "mingles" market, many of the units have features that would appeal to co-buying singles or couples: shared common areas such as the kitchen, dining and living rooms but two nearly equal-sized master bedrooms with baths. Nearly 30 percent of the units in each complex have been snapped up by "mingles," Sharlot said.

"These are very different times," he said. "The only way we developers can survive is to see what is happening, what people will purchase and be flexible about it. You have to become very creative and tuned in to what people are telling us they're interested in."

A recent survey of 10,000 Northern Virginia singles with incomes between $15,000 and $27,000 showed that 77 percent of them would consider co-buying with a friend, partner or couple if that was the only way they could afford to own a home. The Pulte Home Corporation, a national home-building firm, conducted the survey.

Another housing alternative under scrutiny in Northern Virginia suburbs is the "accessory" apartment, a separate unit with its own kitchen and bath within an existing house. In some cases, attics and basements have been converted to such apartments, nicknamed "granny flats."

Although Fairfax County is considering the concept, Arlington is the only jurisdiction now that allows such units--and then only if they are within certain zoning districts or if they are designed as an "in-law" unit. In the latter case, the homeowner must assure the zoning administrator in writing that the unit will be used by a relative and will be removed when that arrangement stops.

"There's a misconception that the need is only for the elderly or the physically handicapped," said Fairfax Supervisor Martha V. Pennino (D-Centreville), an early supporter of the concept. "There's a large group of younger people . . . who don't really need large homes but have a right to live in Fairfax County.

"But this has to be done in such a way that it doesn't change the character or appearance of the community. We don't want communes springing up all around, and we're going to make darn sure people don't move in mobile homes or modular units."

Leo Baldwin, housing consultant for the American Association of Retired Persons, says that accessory apartments present a practical solution to the housing needs of the elderly. Nearly 70 percent of people aged 65 or over own their homes, he said, and nearly 50 percent of them are spending 40 percent of their income on housing costs, "which cuts down on some of the other necessities of life."

If they could rent out such apartments or live in them themselves, Baldwin said, the elderly could save money and gain a sense of security while maintaining their privacy.

In Arlington, "between 4,000 and 14,000 existing houses could offer the potential of having accessory dwelling units if zoning changes are made," estimated Gary Kirkbride, deputy chief of the county's planning division.

Although houses built years ago generally are spacious enough for large families, future housing--particularly in the cramped, close-in suburbs--may well be much more compact.

"Housing authorities and private developers have to look now more than ever at cutting square feet," said Deidre Coyne, spokeswoman for the Fairfax County Department of Housing and Community Development. Most living rooms go unused in homes with family rooms or finished basements, she said, and dining rooms also can be wasted space when there are large kitchens.

"Do you really need all that space?" she asked. "In the past 10 years, people got over the idea that they had to have grass on both sides of their house and accepted town houses. But people still have hopes for more space than they really need, whether it's an extra bedroom or family room or den.

"The developers and builders probably see the writing on the wall, but it's a matter of getting out the marketing concept of living in less space with fewer rooms if they want to come close to owning a house."

Beverly Steele, an analyst with Alexandria's office of housing, agrees. "There's a change in lifestyle," she said. "People can't afford to go out and buy a standard single-family home on a lot in this market. So what you're looking at in the future are smaller units. People are going to have to be satisfied with living in smaller spaces."

"The smaller unit isn't a prediction but a reality because of the cost per square foot to build and utilities and energy," said Bob Johnson, executive vice president of the Northern Virginia Builders Association. "But in the future, I think you're going to see smaller housing units on larger parcels of land. . . . People want more privacy, more space land-wise as opposed to house-wise."

But Johnson also contends that people will be content with smaller houses "only as a starting home," particularly in Northern Virginia's market of upwardly mobile professionals.