Feature Article - March 2007
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A Plan Four All Seasons

Four-season design for recreational enclosures

By Kelli Anderson



Beautifully done

Changing for the better also includes greater adaptability to conventional looks and a variety of aesthetic choices for four-season designs. The days of the single-use covering over a lone pool or single tennis court are giving way to combining these structures into existing athletic facilities.

"I think there's a trend that these structures are becoming more integral with more complex projects," said Bruce Wright, editor of Fabric Architecture, a publication of the Lightweight Structures Association (LSA) of Roseville, Minn. "They're not all by themselves, but integrated with other building parts."

Although a greenhouse look still has a classic appeal, some manufacturers are capable of creating a conventional facade that blends into virtually any style or material including brick, stone, stucco or wood.

As technology improves, so does the versatility of these structures, which boast wide expanses of open interior space and dramatic exteriors of soaring, sparkling, almost free-form designs. From contemporary to classic, there is a style and material to suit every need.

"It's just a beautiful facility," said Lane Walberg, senior program director of the Downtown YMCA in Jackson, Miss., of their panel-and-frame pool enclosure. "And it's very low maintenance. I will also say this—we had strong winds from Hurricane Katrina, and it didn't blow panels off the roof. It held strong."


Going strong

Beauty and strength—not always synonymous—are a special feature of these often-fragile-looking structures. It is not uncommon to hear stories of conventional structures faring far worse than their fabric- or panel-and-frame-structure counterparts during hurricanes, high winds and tornados.

"When in '99 a tornado hit Oklahoma City," recounted Alan Dodson, president of a distribution company in Garland, Texas, "it destroyed every roof on the college campus except ours—the frames weren't affected at all."

For some manufacturers using aluminum rafters and columns, the amount of deflection—or how stiff a building is—has reached impressive heights (180 feet) allowing both larger spans of open interior space and greater strength to withstand movement while preventing thermal breaks between glazing.

Fabric structures also post some pretty impressive stats. "The advantage fabric has over other building materials is that it is more flexible and can withstand the elements," said Beth Hungiville, managing director of LSA. "There are strict regulations and guidelines to withstand winds of a certain amount. We pass them every time."

One reason fabric structures are so flexible, and what makes them as strong as and sometimes stronger than their traditional counterparts, involves the primary engineering use of tension in fabric structure design as opposed to compression in conventional construction.

However, despite the strength a structure may possess, some will require more monitoring than others when it comes to facing the elements. For some structures like air-supported fabric, constant monitoring of internal and external air pressure, and measuring wind and snow loads, is a must.

"Weather is a consideration," admitted Fred Marty, executive director for the Generation Sports Complex's STN Sports Dome. The structure can withstand winds of up to 70 miles per hour, but it's not as likely to make it through a tornado or hurricane. "Snow loading isn't as much of a problem because as heat rises it melts the snow, which slides right off. But the challenge is to consider handling all those factors."