Some highly innovative new home designs are surfacing in the United States - homes specifically designed to meet the needs and demands of the marketplace. A ''bubble house,'' for example, is built with an unusual system of spraying polyurethane foam on a huge inflated ''balloon.'' It's faster and less expensive to construct than a conventional house, and the resulting structure is stronger and more energy-efficient, as well.
Another type of new house now being offered to buyers is designed for two families. It is not a duplex, but rather a single home that is planned for occupancy by two families or other nonrelated groups.
The bubble house is such an unusual architectural concept that it takes some time to adjust to the new lines, shapes, and room arrangement. It basically consists of a large dome with several smaller, overlapping domes.
The construction process starts with a deflated air form firmly attached to the foundation. At this point, the house looks like a giant, limp balloon.
After the balloon is inflated, it is sprayed with polyurethane foam on the entire interior surface.
Steel-reinforced concrete is applied to the polyurethane foam underside. The form is then removed, wall openings finished, and a liquid form of polyurethane foam applied to the exterior.
The construction process takes from 7 to 10 days. About 80 percent of the construction work takes place inside a controlled environment, which means fewer delays because of the weather.
In addition to the speed and simplicity of construction, the designer points out the following advantages:
* The dome house will deliver an 80 percent saving on energy costs, mainly because of having much less exterior surface than comparable conventional structures (34 percent less) and having no supporting walls to conduct heat through the outside surface.
* It is twice as strong as a ''stick-built'' house, despite the absence of those interior load-bearing walls.
* The aerodynamic dome shape will withstand 40 percent more wind than rectangular homes.
While the bubble house seems appealing in both exterior appearance and inside livability, it also does not seem incompatible with surrounding conventional homes. Neighbors point good-natured fun at it.
''It looks like a community of ground hogs had a bubble-gum-blowing contest, '' one neighbor quips. Another chimes in: ''It looks more like an eskimo's igloo or a prototype of a home to be built on the moon.''
Of course, the idea of a dome design is not at all new. The first ''homes'' were dome-shaped habitations in prehistoric caves. Later, animal hides were stretched around bent branches from nearby trees to provide a ''dome'' shelter. In the Middle Ages, the builders of the great cathedrals took advantage of the grace and strength of the dome. In fact, the Latin word domus means house. Domestic and domicile are also derived from the word.
The dome house today is clearly a case of man's using his creative ability, coupled with modern technological resources, to design a better habitation, keyed to the needs of the times.
The 1,844-square-foot house, situated in West Des Moines, was designed by Fredregill Architects and developed by Techmar Corporation. The design has been selected for the Better Homes for All Americans series, established by Better Homes and Gardens magazine.
The ''home built for two families'' is another new, yet different approach to solving the housing problems of the 1980s.
An increasing number of builders and developers are offering homes designed specifically for two families. Normally, they include two master bedrooms and oversize kitchens and living rooms.
Investing in a house with a co-buyer and co-resident would take some real ''getting used to'' for most families, but it is a way for first-time buyers to enjoy the benefits of home ownership and start building equity for a home of their own. While most of today's co-buyers are among the first-time lot, many are older empty-nester couples whose children have left on their own.
The new breed of co-owner/resident houses includes the conventional detached house as well as condominiums and attached town houses.
The largest number of housing units designed for co-buyers are in southern California, Florida, and Texas, but the trend is emerging in markets throughout the US.
One builder, for example, is offering a 3,000-square-foot house for co-buyers which includes two master bedroom suites (400 square feet each), a large kitchen and living room, Jacuzzi, sunken entertainment area, and swimming pool extending around two sides of the house. The price is $300,000.
Another builder offers a two-bedroom attached town house with 1,257 square feet of living space, including master bedrooms upstairs and downstairs, for $54 ,950.
Many questions about this new concept inevitably surface. For example:
* What happens when the two resident groups want to use the entertainment area in a different way at the same time?
* Who goes to the door when the bell rings?
Co-owning and co-residing in a house is a workable solution for only a small number of home seekers, because most families would rather move into a boat or a hand-built cabin in the mountains to maintain their privacy.
New home designs, concepts, and materials will continue to evolve as long as there continues to be a strong motivation for families to own, or at least partly own, their own house.
Actually, that motivation seems to be getting stronger by the year.