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Interior Dynamics

A room that encloses an indoor swimming pool and does it well – by staying comfortable throughout the year, for starters, while also being easy on the eye – is something truly marvelous, says interior-watershape designer Kevin Ruddy. He addressed the basics of indoor comfort in a recent article; this time, he discusses materials of construction, finishes and what it takes to make pool enclosures stand up to moisture as well as the scrutiny of today’s design-conscious clients.

A room that encloses an indoor swimming pool and does it well - by staying comfortable throughout the year, for starters, while also being easy on the eye - is something truly marvelous, says interior-watershape designer Kevin Ruddy.  He addressed the basics of indoor comfort in a recent article; this time, he discusses materials of construction, finishes and what it takes to make pool enclosures stand up to moisture as well as the scrutiny of today's design-conscious clients.

Designing structures to surround indoor pools offers the watershaper the fundamental challenge of creating an interior space that needs all the functional characteristics of an exterior one. That’s so mainly because ordinary residential structures aren’t made to enclose anything that even remotely approaches the moisture levels encountered when an indoor pool is surrounded and separated from the open air.

This leads to consideration of the air-handing, temperature-control and humidity-related issues covered in another article on this subject (click here), but it almost always leads as well to a need to balance those practicalities with a natural desire on the part of clients to have a room that is aesthetically pleasing and fits into its architectural context.

This balancing act sounds simple enough, but the truth is that getting it right often leads you to unusual solutions involving building materials – and especially surface materials – that are almost always reserved for outdoor use. Taking the pool inside, in other words, means thinking about stucco, pressure-treated lumber, exposed-aggregate decking, stamped concrete, stone, brickwork and a host of other possible materials in what are atypical situations for the average designer or builder.

And believe me, client demands for these surrounding structures run the range from the traditional and formal straight through to the sleek and modern, hitting on every possible style in between. In each case, you need to anticipate and accommodate the burdens those choices place on specific systems and set things up in such a way that the moist air in the room doesn’t attack the structure meant to contain it.


In my first article on the construction of indoor pools, we defined the physical challenge in terms of technology and the equipment needed to control temperature, humidity and air quality. Let’s give that discussion a sharper focus by considering the case of clients who wanted to put a grand piano in the same room with their pool.

At first, that seems like a crazy request: The mere thought of placing a delicate, highly sensitive musical instrument near an indoor pool was like asking for trouble with respect to humidity alone, not to mention temperature. But as we thought about it, we knew that we could create a suitable environment because we know how to control all of the primary variables the piano would be encountering.

We knew, for instance, that we could set air temperature at a level higher than the water temperature to control humidity and avoid damaging condensation (albeit those temperatures would both be a bit lower than they would be in a typical pool room). We knew that use of an automatic pool cover would reduce evaporation. Finally, we knew that we could set up the interior space in such a way that air would move through it efficiently and that everything about the space could be carefully controlled.


The range of possibilities for the exteriors of pool enclosures are truly limitless – everything from familiar glass-type structures all the way to architectural additions that can’t be recognized as pool enclosures until someone peeks through a window.

In other words, as tough as it might sound to set things up in such a way that you could have a piano alongside a pool in an indoor space, it’s not all that different from the challenges posed by using standard two-by-four stud construction or materials such as dry wall or paint inside a pool enclosure. All of them, after all, are highly susceptible to damage by moisture.

We also know and have been forcefully reminded through the years that, given the opportunity, airborne moisture will find its way into anything exposed to it – walls, attics, plenums and any other aperture, space, structure or material to which it has access. There’s nothing like the thought of dealing with rotting or warped wooden structural members at some future date to focus your attention on getting things right from the start.

One critical area of concern, for starters, is lighting fixtures that are not specifically designed for use in high-moisture environments or properly sealed. Another is in the upper reaches of large, tunneling skylights, which, if not properly and thoroughly vented, become moisture traps that can lead to all sorts of aesthetic problems and larger issues of the sustainability of the enclosure and even nearby structures.

But getting back to the initial point: If a client asks you to set up a grand piano alongside an indoor swimming pool, it can be done with all the style you’d find in a Georgian music room – but only if you know all the factors you need to balance and can keep them straight as you set up the environmental systems. It comes a bit closer to rocket science than many designers or contractors are comfortable with, but it’s not beyond reach.


Our focus this time is on aesthetics and on how you can choose and array materials to create a functional space that will stand up to the critical eyes of your most discerning clients.

I raised the story of the piano to make the point that you can use just about any material and any style in the space surrounding an indoor pool. For a variety of other practical reasons, however, it’s advisable to stick with materials that are better at withstanding the elements than are most materials commonly used in indoor spaces.


If the materials are chosen appropriately and the systems are set up in such a way that temperature and humidity are controlled, there’s really no limit to the design possibilities with indoor aquatic structures – nor to the sorts of features and details (even tapestries) that can be included within the space.

Ceilings are a particular concern and will tend to take the brunt of the beating moisture can inflict if there’s any lapse in environmental control. For that reason, we make sure that both the basic construction and finishes are going to stand up to the amount of moisture that can be present in the room.

While it might seem odd, this doesn’t necessarily rule out classic wood construction. In fact, exposed post-and-beam construction or wood ceilings finished with tongue-in-groove cedar panels (back-sealed with a vapor barrier of some kind, as described in the sidebar just below) are among the most desirable of all types of construction for indoor-pool enclosures.

Containing Vapors

The term “vapor barrier” refers to a membrane that is placed between a finished interior surface and the structural supports of the building behind it. By design, it creates a border between the materials you see and those you don’t.

If, for example, you use standard batted insulation under tongue-and-groove paneling but fail to use a highly efficient vapor barrier, moisture will get to that insulating material and saturate it over time. Eventually, the moisture behind the paneling will destroy it and do significant damage to roof timbers as well.

There are all sorts of vapor barriers out there, and they’re made from a variety of materials. Most are quite effective if properly installed, which means using special nails and staples that won’t corrode, careful taping and, usually, application of some form of silicon sealant.

— K.R.

Open-beam construction works well primarily because the openness of the structure benefits from free movement of air. If you’re able to expose the wood members to the outdoors with some sort of open skylight, for example, and finish them with a good, moisture-resisting lacquer, varnish, tung oil or polyurethane finish, they will prove to be not only durable but also quite aesthetically pleasing. (The sealer or finish should be applied in four or five coats – and just how durable it must be will be determined by whether the pool will be covered or open all the time.)

For the most part, however, indoor pools are enclosed in structures made using aluminum frames and glazing – much more moisture-resistant and, done well, quite easy on the eye. These buildings, which can easily be attached to a new or existing home or set up as stand-alone structures, have mostly been designed with swimming pools in mind and feature windows, doors and framing designed specifically for challenging environments.

Many of these structures have lots of glass, which lets in a great deal of light and efficiently ties the indoor space into its outdoor surroundings simply by virtue of being transparent. Also, many of the prefabricated structures feature retractable panels in the roofs that open the pool area to the outside air during the warmer months – a substantial operational and aesthetic plus.


Whatever material you select for the structure, one of the most important points in construction is avoiding penetrations that give moisture any access through the interior surface to the structural members.

As mentioned above, lighting fixtures are a particular concern and must be UL-approved for applications in moist conditions. These sorts of fixtures are designed so that the unit is completely enclosed from behind. Often, however, contractors will use other fixtures: Particularly popular are the familiar “high hats,” which offer nothing to resist the migration of moisture to points behind the fixture.

It’s a Wonderful Pool

The most advanced designs for indoor-pool enclosures focus on creating multi-functional spaces. We at Omega Pool Structures have worked on several projects in which the pool could be completely covered with a hard surface that made the space perfect for hosting large social gatherings.

A few companies manufacture aluminum trusses that can be mounted on the coping of a swimming pool to support a platform floor. There are also mechanical floor lifts and retractable floors (don’t forget the classic film “It’s a Wonderful Life,” in which James Stewart dances with Donna Reed before taking an unexpected dip). We’ve also worked with facility that serve the needs of handicapped children in wheelchairs, installing a floor that rises from the bottom of the pool to a level flush with the decking: The kids are wheeled on the floor and then lowered into the pool.

Such systems are available, but they are typically quite expensive and require a great deal of structural and mechanical engineering – the subject, perhaps, of another article.

— K.R.

What happens when inappropriate fixtures are used can be grim. I’ve seen cases where moisture has gotten behind a high hat and cause the wood framing of the ceiling to rot. Such problems often aren’t detected until the ceiling starts to sag and fail structurally, and once that level of destruction is reached there are few options beyond wholesale replacement.

The right lights have closed canopies and a very small number of openings for screws or electrical wires – each of which must be sealed with silicon or some other recommended sealant. We also use a large number of flush-mounted fixtures that involve no significant penetration of the interior surface at all.

Doors and windows are also key features – and of even greater concern than lighting fixtures because they are, of themselves, structurally significant components. Once you get beyond pre-fabricated structures designed specifically as pool enclosures, however, the unfortunate truth is that major manufacturers of doors and windows do not think much in terms of moisture-ready products. In fact, it isn’t unusual for a client to select a door or window for aesthetic reasons only to discover that using the product in a moist-environment application will void the warranty.

Where we must work with commercial doors and windows, we do the best we can to seal and finish components such as windowsills or door jambs and run into problems only rarely. The important point here is to communicate with the client, prepare them for what might happen and inform them of the need for regular maintenance and upkeep of the woodwork – that is, refinishing and resealing every five years or so.


In most of our projects, we usually end up installing some system of retractable roofing or skylighting – and my sense is that this happens because we do such a thorough job of explaining the way indoor-pool environments work.

We tell our prospects and clients right up front that, whether part of a pre-fabricated structure or installed in conjunction with standard post-and-beam construction, all of the mechanical and air-handling issues that come with indoor pools are eliminated when the roof is pulled back or the skylights are open. The thought of lower operating costs through the summer is, it seems, quite persuasive.

Most of the savings have to do with not having to air condition the space through the warm season. Indeed, those savings are often significant enough to pay back the added cost of a retractable roof, for example, in just a few years.

Our discussions of skylights and retractable roofs often lead to questions about what happens when it rains. Yes, there are rain sensors designed for use in these applications, but in most systems the client must push a bottom – and if they’re not home when the rains come, the pool area can be drenched.


There’s a drama to these prime interior spaces that can’t be denied, and the fact that just about any building material that will stand up to (or that can be finished to endure) outdoor conditions can be used to make them beautiful is a key advantage that should be recognized and exploited by more designers.

That’s not a problem, we say, when and if the rain is falling on a stone, concrete or exposed-aggregate decking or hitting stucco walls – thus opening helpful discussion of the finish materials we recommend for use around the pool and our focus on materials suited for exterior applications. And we explain their advantages with respect not only to cloudbursts but also as related to obvious issues of splash-out, pool entry and exit and more.

We’re also big advocates of having operating windows on vertical walls. They aren’t as efficient as skylights or retractable roofs in addressing moisture issues at upper room elevations, but they go a long way toward making indoor pool environments more pleasant all year long.

The more light and exterior views that you bring into the space, the better. In fact, indoor pool areas that lack much by way of fenestration can be distinctly claustrophobic because clients anticipate a connection to the great outdoors when they’re around water. The use of windows at eye level and of glass roofing or skylights overhead effectively opens the space, makes an enclosure (of whatever style) both light and airy and generally makes the room a more attractive place to visit.

Ultimately, our goal as designers and installers of enclosures for swimming pools is to create spaces that invite and excite our clients just as much as outdoor watershapes. When you remove the distractions – excessive moisture, contained odors, any sense of claustrophobia – clients get a positive “vibe” from the design, will use the pool more, probably will take care of it more effectively and will be much happier with your efforts in the long run.

You might even end up being invited to the occasional poolside piano recital.

Kevin Ruddy is president of Omega Pool Structures, a Toms River, N.J.-based firm that specializes in the design, engineering and construction of indoor swimming pools. Ruddy’s career in watershaping began 18 years ago, after he spent some time in the home-building industry and decided to apply what he’d learned to building entire backyard spaces that included pools, spas, landscaping and associated structures. Before long, he saw the need in his area for a company focused on the indoor-pool market and established Omega Pool Structures in 1987. The company now works on indoor pools nationwide and established a pool-construction division in 1993 so it could build many of the pools it designs. Ruddy is an active member of both the National Spa & Pool Institute and the National Homebuilders Association.

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