Building An Indoor Pool: Construction Overview

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Sometimes, you just don’t want the summer pool season to end. But building an indoor pool means you can swim year-round, inside, in complete comfort. 

Outdoor pools are subject to the elements and the freeze and thaw cycle. If you live in an area of the country where the weather dips below freezing in the winter, you have to spend a lot of time, energy, and money winterizing your pool and its plumbing. Indoor pools don’t have that worry, so you can enjoy them year-round. 

So if you like the idea of having a swimming pool, but you’re frustrated by short swimming seasons, blazing heat, or pesky bugs and critters outside, it might make sense to build your pool indoors. The only limits on the possibilities are your budget and imagination, so let’s explore the idea of creating an indoor pool. 

Indoor Pool Construction

Indoor swimming pools are typically more expensive than outdoor construction. The easiest and least expensive way to add an indoor pool is when you’re building a new house. But that doesn’t mean you can’t decide to add it to your existing home. You just need to keep a few things in mind. 

There are three main types of pool construction. All of them are suitable for an interior location. So, you can choose whether you want a vinyl liner, a fiberglass shell, or a concrete and plaster pool. 

Builders working with outdoor pools almost always slope the deck surrounding them away from the water. This design helps prevent dirty rainwater or runoff from entering the pool. However, the slope is usually toward the pool for two main reasons when you build inside. 

First, there’s less risk of debris running into the pool because it’s inside of a structure and protected from the elements. The second reason is that this slope toward the pool helps keep the water away from the inside walls. Otherwise, accumulated water from splashing could damage your home.

Because the pool will be inside a protective structure, you won’t need everything to be all-weather tough. So, the range of options for things like tile, coping stone, and decking material grows much broader.

Your choices for construction materials will also need to account for the additional moisture created by the pool. Like building a bathroom, you’ll need to use waterproof materials in some locations and plastic vapor barriers to seal off the rest of your space from the pool room. 

Your builder will help you determine which materials to use, but some options include Dryvit, green board, and Wonder Board. They’re all water-resistant or better. 

Choosing your Indoor Pool Site

If you want to build an indoor pool, you’ll need to find a space large enough to accommodate both the excavation of the site and its protective structure. You’ll need to meet with an architect or pool builder with indoor pool construction experience. 

Some builds, particularly those with a factory-built vinyl pool, might start with an existing structure. For example, if you have a building with cavernous space and ready access for construction machinery, installing a pool inside it may be possible. But, this is a relatively rare circumstance and probably will only work for small indoor pools. 

More commonly, an indoor pool build starts with excavating the pool site and installing the pool’s infrastructure. Then, the construction team erects the building around it. 

A dedicated structure with a swimming pool and all its components is the pinnacle of an indoor pool building. Of course, starting from the ground up costs the most money, but having a structure dedicated to the pool is the best option.

Indoor Pool Add-ons and Options

This process can be pretty expensive, especially if you want the structure to accommodate other activities besides swimming. For example, you might want a bathroom and changing room inside the pool building. You might even decide you want a space for doing laundry or storing extra towels and pool toys. 

Now you’re not just building a pool. You’re designing a fairly elaborate structure. Because it’s challenging to go back and add more things after the build is complete, you need to think long and hard about all the possibilities for your structure and pool. 

Don’t forget, you’re also going to need a reasonably substantial space to house the equipment for the pool. For example, you’ll need space for your pumps, filter tanks, chemical feeders, and heater. 

Some other considerations include:

  • Deck Space–Will you want a lounge area around the pool? 
  • Entertainment–Consider adding a bar, kitchenette, or TV area. 
  • Sauna and Gym–Adding recreational rooms has benefits. 
  • Skylights and Windows–Do you want to feel like you’re outside? 
  • Privacy–If you have lots of eye-level windows, think about tinting or frosting them.
  • Lighting–Consider using color-changing LED lighting around the pool. 

Ventilation for Indoor Pools

Ventilation is the single most crucial construction consideration for building an indoor pool. Without a robust system to circulate and dry the air, pool water evaporation can become a nightmare inside your pool building. 

If your pool is going to be in a section of your home, the increased humidity can ruin things quickly. High humidity can damage paint, artwork, electronics, and other infrastructure. 

So to mitigate the risk, your builder will help you design a ventilation system that can maintain a normal, safe humidity level. For example, some systems read the humidity in the ambient air, automatically circulate fresh air into the room, and dry the existing air with an air conditioner or dehumidifier. 

You also have to be careful about the placement of fans, registers, and air handlers, as circulating air directly across the pool’s surface can increase humidity, setting your system on course for an uphill battle against moisture. If you add water features like waterfalls and fountains to your build, they can also increase the moisture level, requiring you to bump up the size and capabilities of your ventilation system.

Anytime there is a widening disparity between the water temperature and the room air, the humidity level will increase. That means you need to be proactive and aggressive in maintaining air quality or you risk damaging the surrounding structure. Otherwise, you will have condensation all over the walls and windows, and that moisture can become a nuisance and hazardous.

You also need to maintain constant air circulation, or the smell of the sanitizing chemicals in your pool’s water can become noxious. 

Ideally, you will have a single system that controls all aspects of the pool’s operation so that it understands the water temperature, ambient air temperature, and humidity level. This way, it can act independently to keep things comfortable and safe. 

The Costs of an Indoor Pool 

Vinyl or fiberglass pool construction is often slightly less expensive than plaster. But even at the low end, you’re going to spend at least $50,000 for a professional pool installation. 

A good rule of thumb for planning an indoor pool design budget is to start with a figure for just the pool you want. Then, double it to account for the structure and the added systems around it. If you’re designing a pool for an existing space, retrofitting your building and the pool construction will be more difficult, so you won’t save much money. 

You also want to use your imagination a bit. However, because the budget will be significant, don’t limit your choices unnecessarily. 

For example, if you’re going to spend $100,000 on a building with a ventilation system, maybe you can go a little bigger and increase your pool’s size. Lap pools, cocktail pools, and spas are great, but can you spend just a few more dollars and make the pool bigger? 

Perhaps you might want to add additional rooms around the pool or make the space large enough to host a party. All your decisions need to be cohesive and part of the plan you make with your builder and designer. Let’s look at some features that will increase the cost and make your pool more accessible and fun. 

Lighting and Ambiance

Most indoor pool builders will suggest adding lots of natural light. Otherwise, your indoor pool will feel a bit dark and claustrophobic. So, it may seem like overkill to add many windows and multiple skylights, but they will allow you to feel a bit more comfortable. 

Consider that you may want to use some frosting or tinting of the glass to maintain privacy. 

Retractable Roof

By adding a retractable roof, you can take a well-lit indoor pool’s “open-air” feeling to the next level. It won’t be inexpensive, but doing so will allow you to enjoy being outside when using your pool in ideal weather. Then, when it might rain, or it’s too cold, you can close the roof and still enjoy the water. 

In some areas where the sun is boiling hot, you may even use the retractable roof like a giant shade, closing it during the hottest parts of the day. 

Enjoy Your New Indoor Pool 

If you enjoy being poolside, but the changing seasons or outdoor nuisances are a hassle, consider building an indoor pool. It’s not inexpensive, but a swimming pool is already a substantial expense. 

So, take a careful look at your options, consult with an experienced designer or builder, and work out your budget. Then, use your imagination to make the best indoor pool you can. Get started today!

The Pool Care Handbook & Video Course

by Swim University
This is an illustrated e-book with detailed videos and step-by-step instructions on how to best care for your swimming pool. 
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