Housing the growing generation of older Americans pinpoints a classic paradox.

While providing housing designed for a graying group of moderately affluent to really wealthy persons may be an exciting challenge in an ever-broadening market for builders, there is also the recognition that many retired persons are much concerned about the rising cost of shelter and the lack of what they regard as suitable dwelling units.

As a matter of basic facts, a couple or individual are likely to be able to handle retirement with the least possible trauma if the place of residence and the attendent living conditions are essentially pleasing without being financially burdensome.

Until recently, older persons with adequate retirement incomes usually could face the future with confidence if they owned their own dwelling without any appreciable mortgage. However, the recent increases in the cost of energy have added another dimension of financial insecurity for owners and tenants who pay their own utility bills.

"The recurring theme" of a conference set up here last winter by the Federal National Mortgage Association -- and supported by "hundreds of retirees who wrote to us" was that "retired people are finding it increasingly difficult to obtain satisfactory and affordable housing," said Oakley Hunter, FNMA chairman and president. He pointed out tha inflation has taken its heaviest toll on retirees living on fixed incomes.

Yet, inflation also has been a positive factor in ability of some recent retirees to achieve a new living style while actually enhancing their financial status.

Consider the case of Charlie and Betty. They retired last year with at least a moderate private pension and Social Security benefits. Two years earlier they had purchased a two-bed-room condo apartment on a Florida waterway near the ocean for less than $40,000. Before they made the permanent move from suburban Washington to Florida, they sold their home of a dozen years for about $130,000. With the over-55 income tax break, they salvaged all of the net profit from their larger home as a nest egg for the future.

At last report this couple was living comfortably, getting involved in their community, using their boat to be waterbird voyeurs and not missing the Washington winters.

But going the Sunbelt route doesn't ring everyone's bell. Some soon-to-be retires have built or bought places in the hills or on or near the nearby Atlantic beaches with the idea of living there permanently after retirement. Some Washington area retirees live in mobile homes near Fenwick Island.

Others sell large, family-style houses and buy smaller condominium apartments or town houses in this area to stay near their friends and children -- and clients whom they serve as consultants. Other senior couples are selecting one of three area adult communities that have dwellings and facilities geared to retired or semi-retired persons.

In this area, where early retirements are common among military and federally employed persons, empty-nester couples and singles often make their into-retirement housing moves before reaching age 60. One goal is a near maintenance-free dwelling in a community with a range of active athletic opportunties.

For some, the next stage of retirement housing might be an even smaller and totally maintenance-free house or apartment after 65 or 70, when there is less inclination to strenuous recreation. "Everyday sessions on the links and courts become once-a-week, shorter sessions but many people in their late 60s and early 70s are still unwilling to sit around and vegetate," commented housing research executive Lewis Goodkin.

Normal aging often takes a toll between 70 and 80, Goodkin added, and "the logical thing for them is to choose congregate housing or a life-care community. This will solve many of their problems and, in the process, it is yet another move into another housing unit."

It has been estimated that there will be 16 million senior households by 1980 and 19.5 million 1990. There are 24 million Americans 65 or older today and that number is expected to increase to 51 million by the year 2025 as the result of longer life expectancy and the maturation of baby boom persons who are now is their 20s and 30s.

A survey made by Multi-Housing News showed that, unlike any other population group, persons in the 55-64 empty-nester category consider health related concerns to be even more crucial than money in choosing a residence. "Access to shopping, hospitals, health and personal care, as well as mass transportation, becomes increasingly important as age takes its toll on elderly mobility."

The same MHN survey showed that Sun Belt states rank behind the North North-Central area in having a high percentage of senior citizens as permanent residents. One conclusion is that there is increasing reluctance er among older persons to relocate to areas far from where they have lived most of their lives.

Another concern of persons nearing retirement after their children have grown was expressed recently by Frank and Louise. They decided to sell their house in suburban Washington and move to a mature community for several of the usual reasons: need for less space and a desire for more recreational opportunities.

Still another reason was their desire to have the peace of mind of living in a community with less likelihood of a break-in robbery during vaction absences. Some suburban couples have been house-robbed more than once during regular winter visits to sunny areas in the South.

Meanwhile, there is a major, mostly unfilled, market for rental apartments for persons over 50. Converting thousands of area rental units to condominiums has increased home ownership in moderate-income ranges but it also has diminished a supply of rental housing that had already suffered from lack of developer-investor incentives in recent years.

A few private rental buildings in this area now are designated for adults or senior citizens. However, many hundreds of new dwellings have been built in this area under federal subsidy programs to provide rental housing for low-moderate senior citizens and handicapped persons.

Consultant William R. Smokin wrote recently: "The new rental market for the elderly, whether government assisted or not, will move away from the provision of 'shelter' alone and toward providing more social services, making possible personal independence and dignity."

While the choice of retirement housing should be an individual or couple decision made on a personal basis, there is also the option to "stay put in the old homestead." Couples known to be at least slightly above average in both income and present housing are among those living in the same houses that they had when their families were much larger. Their thinking seems to be that "as long as we can handle it financially and physically, it's the way we want to do it."

Oakley Hunter, in reviewing the study on future housing needs of retired persons, said that FNMA plans to address the financial concerns of retirees and "specifically, their request that Fannie Mae take a leading role in studying reverse equity financing plans by appointing a study group of industry experts."

The reverse annuity concept is that the owner of a mortgage-free house could set up a program to reverse-anortize new indebtedness and thus obtain regular monthly income payments (in addition to usual pensions and Social Security) in order to live better and more independently in the latter stage of life.

And, while there is a need for subsidized housing to house some aging persons, there is also an increasing market of financially solid senior citizens who seek new types of dwellings and communities that suit their needs. In most cities and towns, housing opportunities for people over 50 have been broaded during the past 20 years.

As the numbers of senior adults increase in the 1980s, so will their political clout. Thus, the housing market will have an increasing challenge to provide more and better housing opportunities for all stratas of the retirement segment of our society.