Indoor Pools: Construction, Ventilation, Design & Cost
By Alan E. Sanderfoot
Thanks for their luxurious design and year-round convenience, indoor pools are becoming increasingly popular with new pool buyers. Though a pool room or enclosure adds significantly to the cost of a pool, it also guarantees perfect swimming conditions year-round. In many regions of the country, a pool enclosure can turn a 90-day swim season into a 365-day pool party.
Any type of pool--gunite, fiberglass or vinyl-lined--can be constructed indoors, and the installations can be as simple as a lap pool or as elaborate as an indoor water park. Many people add changing rooms, showers, exercise facilities, steam rooms, saunas, wet bars and other amenities to their indoor pool installations to create a health spa atmosphere. The possibilities for indoor swimming pool ideas are limited only by imagination and budget.
Indoor Pool Cost and Construction
The best time to plan for an indoor pool is during the design and construction of a new house. With the right architectural help, however, it may be possible to seamlessly add an indoor pool to an existing home. Either way, it is important to work with an architect who has a lot of experience designing indoor pool rooms, says Kevin Ruddy, owner of Omega Pool Structures, Inc., Toms River, NJ. "To do it right, you need a complete HVAC system, and that takes someone who knows what they are doing."
Whether a pool is destined for indoors or outdoors, most builders will construct it the same way with one major exception: an outdoor pool deck slopes away from the pool to keep debris and runoff from entering the pool, whereas an indoor pool deck slopes toward the pool to keep water away from walls. Because an indoor pool does not have to deal with the freezing and thawing cycles that an outdoor pool might have to, builders can use a wider variety of materials, such as glass and ceramic waterline tiles smaller than 6 x 6 inches, says James Atlas, principal of Platinum Poolcare, Ltd., Wheeling, IL.
Architecturally, an indoor pool room may look like the rest of the house, but in terms of engineering, it is quite different-especially when it comes to heating and ventilation, which are key to ensuring comfortable humidity levels. In some cases, you can expect to pay as much for the air quality equipment as you do for the pool. Atlas estimates that indoor swimming pools, including the cost of the pool and structure, start at $165,000 to $200,000.
Indoor Pool Ventilation
The air quality of indoor pool environments has come under heavy scrutiny in recent years. Ideally, the humidity level should be maintained at 50 to 60 percent, either by exchanging humid air for fresh, drier air or by installing a dehumidification system. Any dehumidification system should be carefully designed to make sure that air is not forced across the pool surface, which can speed up evaporation. Rather, air should be evenly distributed over the outside walls to prevent condensation.
When the ambient air temperature reaches the temperature of the water, this is known as the dew point. To reduce evaporation and improve bather comfort, keep the air temperature inside the enclosure two to four degrees above the pool water temperature. Evaporation increases as the room and water temperatures drift apart. "This will begin as droplets on the windows, followed by a sensation of actually raining in the room," Atlas says. Because many people like to heat their pools to 82 degrees, heating the enclosure to 84 or 86 degrees is not practical. That is why a properly-sized dehumidification system is so important. You can dramatically reduce evaporation by limiting the amount of time that water features run. To further reduce evaporation from water features, Ruddy suggests plumbing them separately from the pool. By not routing heated pool water through fountains and waterfalls, the water features stay at room temperature and do not contribute as much to evaporation.
Evaporation and humidity can be reduced dramatically by using an automatic pool cover, which can cut evaporation by 50 percent. Ruddy notes that an automatic cover is the most effective tool for reducing dehumidification costs-sometimes by hundreds of dollars each month.
Proper deck drainage is also important because it prevents puddling, which further contributes to evaporation and high humidity levels. From a design perspective, a low-profile strip drain placed around the pool's perimeter looks much cleaner than traditional hub drains placed every 8 to 10 feet, says Tim O'Neil, operations manager for Downes Swimming Pool Co., Inc., Arlington Heights, IL. To further keep deck areas dry and reduce evaporation, O'Neil suggests installing a radiant floor heating system, which will dry up standing water and ensure that bare feet will not get cold in the winter.
Indoor Pool Structural Support
As with any wet indoor environment, plastic vapor barriers are needed behind walls to prevent moisture from reaching the structural framing members, where it can encourage the growth of mold and cause freeze/thaw damage. Some builders believe that greenboard (a water-resistant drywall used in bathrooms) is sufficient for pool rooms; others recommend a waterproof board, such as Wonder Board. Still others suggest Dryvit, a material designed for exterior applications, which is available in several textures and can be painted.
Meanwhile, do not underestimate the amount of space you will need for the equipment room. For this, you may want to rely on the pool builder's expertise, not the architect's. According to pool builders, architects may tend to undersize equipment rooms, which can make for impossible working conditions down the road if equipment ever needs to be repaired or replaced. Also, if the pool is going to be maintained by a service company, consider having the room accessible from outside so that service techs do not have to go through the home to access the equipment.
Any pool that is sanitized with chlorine will emit odorous chloramines, but the smell can be much more pronounced in indoor pools. Though ventilation systems are capable of reducing such odors, there are additional remedies. One is to use a supplement, such as an ozonator or mineral purifier. This will help reduce the production of chloramines and mitigate the YMCA smell.
Indoor Pools with Skylights and Retractle Roofs
Windows, skylights and sliding glass doors are a great way to create an open feeling, but they can also lead to excessive heat in the summer. Ruddy says it is important to have skylights or high windows that open to let hot air escape; otherwise, you could spend more on cooling your indoor pool room in the summer than you do on heating it in the winter. Better yet, an open roof system and lots of sliding glass doors enable you to treat your indoor pool like an outdoor pool in the summer, he says.
To keep windows from fogging up, airflow must be maintained across the entire width of the windows. Some architects recommend placing vents in both the floor and the ceiling near each pane to ensure a clear view.
Indoor Pool Lighting
Incorporating lots of skylights, windows and sliding doors lets natural light flood the space, but when the sun goes down you will need adequate lighting for nighttime enjoyment and safety. A combination of underwater lighting and wall sconces typically provides sufficient and attractive illumination. Avoid overhead lights, because the bulbs are too difficult to access when they need changing. If you want lighting near the ceiling, consider fiber-optic cable fixtures, which use remote illuminators that are easily accessible. According to Ruddy, the lighting should be subtle-just enough to create the right ambiance. If it is too bright, it could draw unwanted attention through the windows, he reasons.
As you can see, an indoor pool allows you to control everything about your aquatic environment--no matter what kind of weather Mother Nature sends your way. So if you are thinking about installing a new pool, consider making it an indoor one. Do not make the mistake of thinking you can easily turn an outdoor pool into a pool room at some future date. "If you have an existing pool," Ruddy says, "the cost to convert it to an indoor pool will be as much as it would be to build a new indoor pool from scratch."
Photo courtesy of Crystal Clear Pools, Feasterville, PA