CONTEMPORARY CONSERVATORIES have their origins with the 19th-century British passion for accumulating collections of exotic plants from the far reaches of the empire. Whether you refer to them as sunrooms, solariums or conservatories, they are great places for plants, and also for nearly any family activity. A solarium can be a well insulated, four-season addition to the house or a strategy to extend the summer months with a less-expensive three-season room. Today's sunrooms, unlike their predecessors of plate glass framed in wood, are highly efficient, low-maintenance structures. In most cases, they are constructed of extruded aluminum or polyvinyl chloride framing. These durable materials boast colours impregnated in the plastic or include heat cured and chemically bonded paints. Some are guaranteed not to leak, fade or crack. Tough, light polycarbonate laminates or tempered, specially coated glass have replaced plate glass, which is vulnerable to errant baseballs and other accidents. Before the advent of these new materials, heat buildup due to solar gains inside conservatories and solariums caused problems just as serious as those resulting from plummeting seasonal temperatures. The new materials affected the design of solariums, too. It became possible to create curved, structurally strong and aesthetically appealing conservatories. These began appearing on homes in the 1970s. The materials have continued to improve. Today's solariums, some with curved roof designs, are nearly as thermally sound as the walls and windows they replace as the exterior of a home. The majority of solariums are built over decks or patios to provide three-season use, without the added cost of winter-proof insulation in the floor and ceiling. Brenda and Jay Childs, whose acreage is near Saskatoon, are devotees of sunrooms. When they lived in the city, they added a three-season, polycarbonate, curved wall solarium to their home to get more light and more living space. When they moved to the country a few years ago, they found their new, larger home also needed some brightening. They wanted more space near the kitchen and family room, too. Adding a solarium was an easy choice, says Brenda Childs. They knew it would enhance the home's interior while offering views of the beautiful surroundings. "On the acreage, we had none of the concerns we had in the city when it came to things like privacy from people looking in. But we had all the advantages." Hence, there's no need for blinds. Initially, they considered adding a new curved wall, four-season solarium. Then they decided a British conservatory style of addition would better suit the steeply pitched walls of their house. "You can't even tell it's an addition to the house," she says. While the four-season choice adds about 25 percent to the cost, solarium additions are less expensive than most home additions of a similar size. Bart Gaspers of Sunview Solariums, a Saskatoon manufacturer, says four-season construction begins with footings, grade beams and insulated floor, as with any home construction, while the three-season units need a much lower investment in the floor. Childs says their new 10- by 30-foot solarium proved warm and comfortable last winter. "We added a small wood pellet stove and that kept the whole area warm, sometimes too warm." The Childs' solarium serves as their new dining room and a den containing comfortable reading chairs and exercise equipment. They built their new unit facing south, with end walls east and west. "We can now have guests for dinner and it seats 10 comfortably, without all that bumping into one another," she says. "People aren't sliding away from the table as soon as the eating is over, and they get the sunset outside the windows." Gaspers, who built the Childs' new solarium, says the thermally coated glass vertical panels of the PVC window wall system provide a maximum of window space, while providing reasonable R-values and zero maintenance. The translucent roof panels are coated to reduce thermal gains. Steeply pitched roof panels in the conservatory-type units that replicate the traditional British style are generally made of polycarbonates. Glass roofs now account for only one or two percent of Sunview's business, Gaspers says. Typical three-season, curved roof, polymer solariums start at about $12,000 for a basic, nine- by 12-foot unit, and range up to about $25,000, depending on interior finishes and sizes. Conservatory-type units cost slightly more. "The sky's the limit for some," says Gaspers. "It depends on the choices of construction, three-season versus four-season and the interior materials. Like any other addition, you can go as high as you feel you can afford. But it can be a real bargain, too." Unlike some home projects, such as swimming pools, solariums add to the resale value of homes, he says. In addition, kits are available, making it possible for homeowners to construct solariums themselves. Martin Doell of Pyramid Sunrooms in Warman, Saskatchewan, says his company's customers are almost 50 percent rural, and "usually are folks who chose to live in the country and want to maximize their exposure to the outdoors without the bugs and cold of early fall or late spring. "We do a lot of solariums over decks," he says. "We add interlocking steel roof systems that can be shingled and made to appear a part of the home as a result." His company favours an extruded aluminum wall system with tempered glass windows that open to reveal floor-to-ceiling screens. While most of his customers spend about $15,000 on the straight-wall sunrooms, he says the value they add to their properties is generally recaptured if they later decide to sell their homes. "People find that a modern sunroom is made of materials that need less maintenance, and show their age more slowly than the house they're attached to," says Doell. Whether it's a basic enclosed screen porch that keeps out the rain and insects, a fully enclosed three-season tempered glass wall sunroom or a four-season conservatory addition to the home, solariums are engineered to accommodate different snow loads and wind conditions in various locations across North America. Gaspers says homeowners should compare regional and local builders to each other when it comes to pricing their solariums, since differing weather conditions across the continent will affect construction costs.