Top It Off

Enclosing a pool can increase program offerings and help draw new crowds

By Margaret Ahrweiler

In the middle of the day, the pool at the Mission Valley YMCA in San Diego was, without question, the place to be for swim lessons, lap work and recreation. But getting members in the water at 8 a.m. or 7 p.m. was a different story. Sunny Southern California notwithstanding, with a desert climate, temperatures drop into the low 50s at night, making mornings and evenings less than ideal for anyone other than hard-core swimmers. Not to mention, keeping the water temperature constant, even with a heater, presented a constant challenge.

What's more, the aging Baby Boom population driving the YMCA's market (along with everyone else's) had had enough of brisk water, says Dick Webster, executive director of the Mission Valley. They wanted warmth. They wanted comfort. They wanted easy on the joints.

To better serve its market and expand the facility's use, the Mission Valley Y embraced a solution once considered limited to cold-weather climates: a pool enclosure.

Pool enclosures can turn a part-time facility full time and change the entire feel of a rec facility. But along with increased usage and profits, enclosing a pool can float a whole new set of issues through the air, namely: cost, air quality, water quality and maintenance.

The switch from out to in can be done in several ways with varying degrees of permanence. For a temporary indoor fix, inflatable domes can get a facility over a cold-weather hump and come down for warmer weather. Domes also can take a more long-term service as year-round structures.

For a more permanent system, facilities can consider greenhouse-type structures, many of which come with retractable roofs and banks of sliding doors to provide an indoor/outdoor feel. Finally, the brick-and-mortar approach—building a traditional addition around the pool—creates the most solid, "indoor" environment. Before committing to an enclosure system, however, take a good, hard look at who uses your aquatics program and how, advises Dan Meus, principal in Boston-based Graham/Meus Inc. architects.

"If you have a club with a big leisure pool and strong summer program and that's the biggest part of their business, enclosing it with a windowless, totally indoor structure is probably a bad idea," Meus says. "There really needs to be a strong connection with outside."

True building additions and opaque domes can remove that outdoor connection, Meus says, but on the other hand, domes can extend what can only be a three-month swimming season in northern climates.

"If it's set up in the winter and removed in the summer, that can be a treat for members as well," he says.

Glass enclosures create the greatest connection with the outdoors, albeit at the greatest cost, according to Meus, especially for those in cold-weather regions.

"There's nothing like swimming when you can see the snow falling all around," Meus says.

The biggest barrier to these greenhouse-type enclosures is initial cost.

According to Alan Dodson, president of Garland, Texas-based Sun Builders, the structural system alone runs from around $50 to $70 per square foot, before adding the cost of the ventilation system or foundation work needed for the footings.

"Glass coverings run five times the cost of a bubble, and a permanent steel structure is at least double the cost of a bubble," Meus says. "But if you can produce income from it, it makes it worth your while."

Mission Valley YMCA, for one, felt an immediate financial impact from enclosing its pool.

"It increased our swimming activity 400 percent," Webster says. Aquatics programs have expanded to the point that the facility is planning another, outdoor pool that will cater to "hard-core" users—lap swimmers, master swimming programs, water polo and swim teams, he adds. The YMCA will then convert the enclosed pool to a 90-degree therapeutic pool.

Let the sun shine in

Glass enclosure systems also can bridge the gap between users who want an outdoor feel and those who prefer the great indoors.

"When we initially proposed this to our membership, there were a lot of cries that we want open air," Webster recalls. '"Now, the biggest complaint is that it's not closed enough."

Even when closed, the clear roofs allow swimmers and loungers the benefits of natural light without the hazards of exposure to ultraviolet rays.

The dramatic appearance of an enclosed pool can instantly increase visibility as well, aiding in marketing efforts.

"Before we installed the enclosure, our pool was hidden—people never knew we had a pool," Webster says. "Now, it's a focal point. People can walk up to our facility and imagine themselves from our pool."

By increasing the availability of the pool, enclosures can also help make popular programs more accessible. The Almaden Valley Athletic Club in San Jose, Calif., had to compress a year's worth of aquatics lessons into the summer months, with popular programs booked months in advance. But when the club enclosed its outdoor pool with a greenhouse-type system, its swimming program sprouted fins. Ten bays of sliding doors and 16 roof panels open up to create an outdoor feel while providing just enough protection from the vagaries of the San Francisco Bay weather.

"It's had a huge impact on their programming," says Rob Christie, president of the enclosure-system manufacturer that installed the club's system.

While exposure to natural light may not rank high on a California facility's list of priorities, the large expanses of glass can give a huge psychological and emotional lift to cold-weather facilities. For example, Meus is working on an addition with an enclosed glass leisure pool area at The Works, a fitness club in Somersworth, N.H., which is keeping its outdoor pool intact and starting from scratch with an indoor system.

"To be able to feel that sun in the middle of winter, especially if you have small children, is a big boost," Meus says. "It also allows you to use the pool on a rainy day, where you can close the roof but keep the doors open."

The glass enclosure systems feature three key points that make them different from stick-built systems: First, they're built of powder-coated aluminum, which is one of the few construction materials that does not break down when exposed to chlorine or moisture. By building the framing systems off-site to a pool's measurements, the construction team need not cut any beams, which weakens the corrosion resistance. (Cut spots expose uncoated metal, giving that corrosive chlorine an entry point.) These aluminum systems also feature a thermally broken design, which means that the inside parts are separated from the outside parts by rubber gaskets. This limits conductivity and helps reduce the condensation caused by big differences in indoor and outdoor temperatures. It also helps the structures adapt to a wide range of climates, from a Canadian winter to an Arizona summer, Christie says.

Next, they feature retractable roofs that can expose up to 40 percent of the facility to open sky and create an inexpensive, easy way to help regulate air quality. If it gets too humid or hot, you can open the roof. Some roof systems are composed of panels, allowing the option of only opening a few panels. Others feature sliding retraction systems, so that a roof can be "cracked," like a window or fully opened, exposing most of the pool. At the Mission Valley YMCA, the roof opens enough to expose four of the pool's six lanes.

And those roof panels do more than just let in light and air. The roof panels are made of polycarbonate, a tough yet clear resin-based plastic—think of a Nalgene bottle for your roof. Not only is polycarbonate much more durable than glass, it also protects against UV rays, allowing sun worshippers to get their fill without damaging their skin, Christie says. Finally, sunlight helps break down chlorine as well. Polycarbonate's high thermal resistance means it conserves heat (or in the case of hot desert climates, cool) better than insulated glass. The side panels of pool enclosure systems are typically composed of glass, laid between aluminum support beams, with banks of sliding doors—either patio style or the vertical "garage-door" variety that can open to create more of an outdoor pavilion feel. Some systems can incorporate columns of conventional walls with up to an R-20 value of insulation, Christie says.

With improved technology and engineering, prefab aluminum and glass systems can accommodate ever-larger structures. An enclosure system at the Milford/Orange YMCA in Milford, Conn., features a 100-foot wide span and rises to a height of 20 feet to match the existing building, Christie says. The systems will work with almost any pool, adds Dodson—the only thing prohibiting a structure might be a tight site, where the contractor could not squeeze in the foundation footings between a pool and an existing building.


For close to 20 years, the Milford/Orange YMCA in Milford, Conn., had been a bubble kind of place. Its outdoor pool—one of the few in the area—had been covered by an inflatable dome during cold-weather months. For this branch of the Central Connecticut Coast YMCA, the temporary dome gave members the best of both worlds. Members enjoyed being in the great outdoors in the summer, where they could enjoy the bucolic views of the Y's 25-acre wooded property during their leisure or competitive swimming.

But as their second 110-by-100-foot dome (the first lasted 10 years) approached the end of its life span, the YMCA's leadership began looking at other options, says Judy Jameson, executive director of the Milford/Orange YMCA.

"Bubbles only last eight to 10 years; we'd already had two, and it would cost about $100,000 for a new one, and it was very labor intensive to put up," she explains. "It was not financially feasible to continue."

The Milford/Orange Y also sought a more efficient, aesthetically pleasing alternative to the bubble, which "wasn't particularly aesthetically attractive, and it wasn't airtight, increasing heating costs," Jameson says.

A glass system seemed to be the way to go, but the size and shape of the pool had limited that possibility until recently. The large, Z-shaped pool (with a shallow area at one end, lap lanes in the center and a deep end at the other end) and its configuration right next to the main YMCA building posed a challenge for enclosure firms.

"They really had to put their configurations to the test," Jameson says. But with engineering advances, the enclosure firm was able to handle the 140-foot-long span needed to cover the pool properly, along with the 20-foot height to tie the enclosure into the existing building.

The new enclosure system features a retractable roof and open-wide sides to maintain an outdoor feel and tie the pool to the picnic area and playground nearby.

"It will still feel like outside to our members," Jameson says.

A giant erector set

These systems generally get built much more quickly than a traditional structure. Glass enclosure systems, which are manufactured by a handful of firms in the United States and Canada, typically feature powder-coated aluminum framing systems manufactured in a factory to a facility's precise measurements. They are then shipped on site and assembled "like a giant erector set," says David Hoy, general manager of the Pointe Royale Country Club in Branson, Mo., where Sun Builders is enclosing a pool.

Hoy has been impressed with how quickly the structure rises.

"It only takes eight to 10 days," he says. "They come on the site and work seven days a week. It's very fast."

Pointe Royale, an upscale residential (Andy Williams lives there) and country-club community, chose an enclosure system for a high level of aesthetic quality along with structural integrity.

"We decided to spend the extra dollars up-front and save on maintenance," Hoy explains. "Everyone I spoke to with a wood structure had nothing but difficulties fighting the chlorine and humidity. This is basically indestructible."

And once erected, maintaining glass enclosure systems requires little effort, another selling point, Hoy says.

"It's basically maintenance-free," he says. "At worst, if we were to develop a little mold or fungus, it's just a matter of going in and power washing it."

As a testament to the aluminum systems' toughness, Dodson notes that pool facilities he has installed have survived tornados in Oklahoma virtually unscathed.

Leave your architect behind?

And here's an added benefit of working with enclosure systems: You probably don't need an architect—even according to an architect.

"You will want a good mechanical engineer, especially one who knows a good HVAC firm, but you don't really need an architect," Meus says. Sometimes, a structural engineer can help plot the foundations—a foundation of concrete footings supports glass enclosure systems.

Dodson agrees: "Usually, with commercial or public facilities, our client is represented by an architect, but sometimes they just draw a rectangle around the pool area and say, 'specifications by pool enclosure contractor,'" he says. Architects can be important to protect an owner's interests, and he is always happy to work with them, he's quick to add.

Up with domes

For those without the up-front capital to invest in a greenhouse-type system or who want to retain a truly outdoor pool, inflatable dome structures present an affordable and removable alternative.

Most systems go up (and come down) in just a day, using a powerful gas furnace-type blower system, similar to those used in hot-air balloons. The domes attach to concrete beams laid with metal channels around the perimeter, with the "bubbles" made of high tensile, coated polyester or vinyl fabrics that can be either opaque or translucent. A continual level of air pressure keeps the domes inflated; revolving doors serve as airlocks to keep pressure constant despite foot traffic. Most dome blower and ventilation systems incorporate air conditioning or heating units to dehumidify and cool or heat the air, depending on the climate.

Underground ducts can be used to ventilate domes, especially the permanent variety, while lighting—either suspended indirect systems or the more basic pole-mounted variety—is usually included in a dome package as well.

And while domes go up for a fraction of the cost of a glass enclosure system, facilities must factor in the higher maintenance and support costs: You can spend up to $15,000 each season to take down a dome, Dodson says.

Sticks and steel

True enclosure—creating a conventional building—around an existing pool—remains an option as well. This may appeal to users looking for more of an "inside" feel, those seeking unconventional design elements, or those who want to incorporate amenities such as locker rooms or fitness areas, Meus says. Stick-built facilities can use wood (cedar is a popular choice for its water resistance and warm look), glass and steel.

When properly painted with water-resistant paint, steel can hold up to a harsh pool environment—"aluminum could probably last hundreds of years, but when you treat it right, steel might last 120 years," says Meus—but count on careful, costly maintenance to make it work. The moisture-resistant paint, which also is used to coat the insides of water towers, can actually cost more than the steel itself, Dodson says, who used to install steel systems and requires an experienced, specially trained painting contractor to handle it.

Mixing air and water

Each method has its advantages and disadvantages, but any enclosure system brings a whole new set of issues to your pool. Turning outside in magnifies water and its aquatic partner, chlorine. The two combined create the twin nemesis of maintenance: humidity and corrosion. To combat them, a powerful—and appropriate—heating, ventilation and cooling system that balances chemistry, comfort and efficiency is a must.

"We always suggest a true dehumidification system," Christie says. The humidity inside a pool structure should be kept to between 50 percent and 60 percent, he says. While the powder-coated aluminum systems are designed to withstand moisture, a high humidity level can bring a swamp of troubles in many other forms, even to the point that it creates fog indoors.

As pool water evaporates, it brings a gaseous form of chlorine into the air, Dodson says. And since chlorine is heavier than air, the chlorine vapors hang most heavily over the water, creating that "pool smell" that lingers right at nose level without proper ventilation. The most effective ducting and ventilation systems push air away from the pool's surface, where most chlorine fumes are suspended, and pull a regular supply of fresh air inside.

Because of this, the ventilation system and its accompanying ductwork should be planned hand in hand with the enclosure. Ideally, ducts should run at ground level to push the most chemical-laden air away from the pool, Meus says, with more air ducts along the ceiling.

Enclosures with retractable roof systems can ease the load on an HVAC system. At the Mission Valley YMCA, for example, dehumidification consists of opening the roof to let in the dry desert air. The roof openings act as effective, adjustable venting systems as well, Dodson adds, where just a few can be opened to maintain a desirable indoor temperature loss.

Additionally, the sunlight entering the polycarbonate roof helps break down the chlorine gases in the air, eliminating the smell associated with indoor facilities, he says.

Which system works for you?

Deciding which system works best for your facility is a matter of number crunching and research. Glass enclosure systems, along with stick-built additions, require a significant amount of capital. It pays to crunch numbers and see if the additional revenue generated would support the initial expense. Next, talk to the people who know best—other recreation facilities that have enclosed their pools with a variety of systems.

By seeing what different enclosure systems offer, and how they work for a facility, you can make the choice that's best for you and take your aquatic program inside.

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