If you're stymied by double-digit interest rates and housing prices that keep ballooning out of sight, consider trying one of the fastest-growing techniques in real estate: buying with other individuals or mortgagors.

Your partner (or partners in the case of a couple) might or might not live in the unit with you, might or might not intend to continue in the deal for long, and needn't be an equal owner or have an equal share in the costs and tax benefits of the purchase.

How you arrange the relationship is purely up to your financial needs and creativity.

Although not highly publicized, there's a lot going on in the "co-purchase" field in metropolitan areas around the country.

Here in suburban Glendale, for example, a condominium developer is selling two-bedroom, two-bath units that have been designed especially for ownership by unrelated individuals and couples.

Rather than standard layouts with bedrooms off a single hallway, the units at Everett East condominium will come with master bedrooms and full bathrooms at each end of the apartments, for added privacy. In between the bedroom suites are the socalled "common areas" -- the kitchen, dining room, and foyer.

Even the savings and loan association providing the mortgage financing at the project is rolling out the red carpet to groups of two, three and four people on the same loan for a single unit.

In Arlington, Va., a developer quietly has been selling the same concept to the Washington market with what he calls "incredible results."

Out of the first 100 town houses sold at Windgate of Arlington, said Arlen Group Project Director Ray Smith, 44 were bought by unmarried, unrelated individuals "looking for a foot in the real estate door without wrecking their budgets."

About 40 percent of the buyers were male and female couples, about 40 percent consisted of two males, and 20 percent were both female. Virtually all were young professionals, with solid salaries and responsible jobs in downtown Washington, 15 minutes away. Prices ranged from $66,000 to 85,000, or $33,000 to $42,500 for each individual. Down payments went as low as 5 percent for each person.

Smith never advertised his units as having architectural designs that are well-suited to double ownership -- "the word simply got around" -- but he says the layouts were carefully planned in advance with this market in mind.

"This is one of the waves of the future in urban locations," Smith said. "You've got tens of thousands of people out there who are bright, upwardly mobile, and totally locked out of the regular housing market.

"They won't buy a place that's an hour outside the city, and they don't want the hassles of a rundown house in a bad neighborhood.

"They're also not hunt up about sharing a place with someone else -- a friend, a co-worker, a relative, or what have you. The 10 to 15 percent gain in annual appreciation on the unit they co-purchase, plus the tax benefits every April, are far beyond anything they can get out of a rental unit."

The phenomenon is not limited to new condos. Brokers in suburban New York, New Jersey, Philadelphia, Chicago, Dallas and Houston report a steady increase in the number of unrelated prospective buyers, including groups of two and three middle-income professionals and two couples seeking houses.

A real estate lawyer in New York City report that he's being asked to structure an increasing number of partnership agreements between couples who want to jointly buy and occupy detached three- and four-bedroom suburban homes, and cooperative apartments in the city.

A prominent Washington attorney confirms that that same trend is underway on the mortgage side of real estate transactions. Young, middle-income buyers of condos and houses increasingly are being forced to borrow big chunks of their down payments from friends, relatives and others.

Since most banks and savings and loans won't allow buyers to have more than 80 to 90 percent debt against a property at purchase, however, these buyers are getting "back-door" comortgagors.

The mortgagors lend cash to the buyers for the down payment in exchange for an interest-bearing second mortgage against the property that's recorded weeks after the closing with the savings and loan or bank.