NEW YORK — THOSE popular home add-ons now called ``sunspaces,'' stylish versions of residential greenhouses, solariums, conservatories, and old-fashioned sun rooms, may be light and airy. But to the home remodeling industry, they are solid business. Today, these prefabricated sunspaces are part of an estimated $500 million industry, involving more than 60 companies. Sales volume was perhaps $150 million in 1986. And the business is expected to grow over the next few years by estimates ranging from l0 to 25 percent a year.
Sunspaces are in demand because they increase living space, cut energy bills, enable plants to thrive year round, and offer a manufactured alternative to traditional remodeling.
Once located largely in the northeast, the industry has decentralized and firms have popped up all over the country, including the Southwest and California. The Japanese and Europeans are also adapting the idea to their own particular requirements.
Commercial greenhouses have been around for years, but the market for residential versions exploded in the past l0 or l2 years. Used in the 1960s for food production by back-to-the-land proponents, and for solar heat during the 1970s energy crisis, the 1980s have produced a crop of sunspaces for every kind of extended living area, including family and kitchen and dining rooms, saunas and pool enclosures.
Meanwhile, many technical advances have come along, including a special glass that reflects more energy back into a room, improved glazings, and gasketing systems for sloped glazing. Harold Gray, executive director of the National Greenhouse Manufacturers Association in Pana, Ill., which includes l3 residential greenhouse/sunspace manufacturers, says that double and triple glazing are now standard fare, and that the association has worked out refined standards of reliability and safety which are improved each year as research continues. (A few fly-by-night manufacturers offering cheap units have been a problem in the past.)
At one time, says Gray, manufacturers promoted their products to do-it-yourselfers. But few are sold on that basis any more and most purchasers use professional installers. The average prefabricated sunspace unit is roughly 200 to 250 sq. ft. They come in many sizes and many are custom-tailored to individual specifications.
Gray says that frames made of aluminum extrusions hold down the largest share of the market, with laminated wood frames remaining popular for their architectural appeal.
Lee Stanley's sunspace falls into the latter category. In 1974, Mr. Stanley built a sunspace addition in his Waterford, N.Y., backyard so that he could grow natural food year round. It worked. Plants flourished, the solar heat it collected helped warm the house, and it provided more living space.
Soon friends asked him to build similar sunspaces for them and what had been a hobby became, in 1978, a full-fledged business called Solar Additions, Inc. To date, the company has manufactured and sold more than 8,000 sunspaces and generates $6 million in annual sales through 54 dealers in the United States.
``It happened to be a right idea at the right time,'' says Stanley, ``because people in the mid-'70s wanted to conserve fuel by tapping into solar heat, as well as expand space. They were needing larger homes but being discouraged from moving by rising housing costs and mortgage rates.''
He drew on greenhouse designs going back as far back as the 1860s, when Victorian solariums were the fashion, but eliminated the all-glass look by combining glass with redwood, yellow Southern pine, and cedar wood.
Recent research conducted for Stanley's firm, indicates that people are attaching sunspace rooms to their houses to provide kitchen space (20 percent), dining areas (l3 percent) and pool enclosures (9 percent), as well as for use as studios, libraries, audio-visual centers, spas, and bathrooms.
An industry estimate, says Stanley, is that some 350,000 homeowners have added sunspaces to their houses in recent years. Buyers, he says, are usually between 40 and 49 years old with annual household incomes between $51,000 to $100,000. Twenty-five percent of owners are in the $31,000 to $50,000 household income category and 29 percent are in the $51,000 to $100,000 category.
Sunspaces, Stanley has found, usually make a home more saleable. ``A $10,000 sunspace add-on instantly increases the value of an $85,000 home to more than $l00,000,'' he says. Sixty percent of sunspace owners paid between $l0,000 and $20,000 for their add-ons and related installation or remodeling. Package price usually ranges from $30 to $50 a square foot, depending on materials used, architectural style, and the choice of special features and appointments. The general rule, he says, is that the cost of installation, if done completely by outside professionals, is roughly equal to the unit purchase price. If the homeowner does some of the work himself, the cost is reduced. About one-third of those purchasing Solar Addition sunspaces get involved with some part of the installation.
The company pre-assembles sunspaces at the factory and ships them in components for attachment to houses. They have come a long way from being just a hobby greenhouse or a casual ``bump out'' breakfast nook. Stanley says the industry made and sold between 50,000 and 60,000 sunspaces in l988 and will probably see a 20 percent growth in 1989.
``Letting the sunshine in is a terrific way to upgrade any building and add value to any home or business,'' comments the director of marketing for Gammans Industries Inc. of Newnan, Ga.