Can You Install a Hot Tub Indoors? (8 Requirements)

The requirements for indoor hot tubs differ from outdoor ones. Before installing your indoor hot tub, there are a number of factors to take into consideration to prevent expensive damage to your home.

Hot tubs can be installed indoors and have many benefits over outdoor spas. Ensure that the room is able to comfortably fit the hot tub and that there are adequate foundations, flooring, drainage system, water and power access, filtration system, and ventilation to prevent mold and mildew growth.

Good ventilation is absolutely essential in a dedicated spa room. After looking at the requirements in more detail, I’ll show you what’s needed to keep your spa free of moisture and condensation.

Indoor hot tub instalation requirements

Whether you choose to install your hot tub in your garage, basement, or other room in the home, there are certain requirements you must follow to avoid problems down the line.

Hot tub size

Purchasing an appropriately sized hot tub is important for reasons such as reducing running costs, ensuring it fits properly, and that it’s able to be maneuvered easily into place.

There needs to be adequate space around the hot tub to ensure safe access, proper ventilation, and drainage.

While your budget might stretch to a 6-person hot tub, is such a large one necessary? Larger hot tubs mean higher energy costs and more maintenance.

Portable hot tubs are pretty huge, so you’ll need to make sure that the size you choose can fit through doors, hallways, and stairs.

Before signing any contracts, double-check the hot tub’s dimensions and talk to a qualified salesperson about the proposed installation route.

Firm foundations

Hot tubs need to be sat on a flat and level surface to support and evenly distribute the immense weight. Once filled with water, a hot tub can weigh as much as Xlbs/kg.

Unless your new spa is going to be placed on a concrete slab in the basement, the flooring isn’t going to be able to take the weight safely.

You’re almost certainly going to need significant reinforcement, which means getting in touch with a structural engineer.

Avoid the hassle of ringing round by using BuyerZone. Answer a couple of simple questions, and a qualified engineer will contact you with a competitive price.

Flooring material

Now that you’ve got the foundation sorted, it’s onto the flooring material. No matter how careful you are, it’s impossible to avoid getting the floor wet, which makes the flooring one of the most important considerations.

You need to choose a material that doesn’t become damaged by water and isn’t slippery when wet. The 2 materials you must avoid are wood and carpet.

Concrete or non-slip tiles with a matte finish make excellent choices and are both very popular. A more modern, water-safe choice is PVC.

The benefits of PVC are that it doesn’t absorb water, it dries quickly, and it comes in a wide variety of styles.

Drainage system

All the water that finds its way onto the floor needs somewhere to go. When you’re deciding on flooring materials, you must take the drainage system into consideration as well.

The last thing you want is pools of water either around or beneath the hot tub. And because you’re going to need to empty the spa at least every 4 months, you’ll need easy access to the drain.

Water access

A hose attached to a nearby faucet (tap) is the most efficient way of filling a hot tub. But unfortunately, not every room in the house has access to running water.

While you might be able to hook up a very long hose to some other room in the house, I assure you that it’s far easier and more efficient to get a dedicated faucet installed.

Hot tubs don’t only need refilling with water after fully draining a few times a year. Spas continually lose water, so they need to be topped up on a regular basis.

And in order to keep the water fresh, partial drains should be part of your water care routine. Partially draining the hot tub makes balancing the sanitizing chemicals a whole lot easier.

Without easy access to a nearby faucet, it’s all too easy to let your water maintenance routine fall by the wayside.

This leads to a build-up of nasty bacteria that is harmful to you and your hot tub, and it can ramp up running costs by increasing the number of chemicals you use, which have less and less effect tackling the unsanitary water.

Power access

You’re going to need to plug the hot tub into a wall outlet or have it wired directly into a 220v, 230v, or 240v connection using your home’s central circuit breaker box.

A lot of people in the United States don’t realize that their home already receives 220v which is split into 110v, so it isn’t that big of a job.

If you don’t already have a proper wall outlet, you’re going to need to get one installed by a licensed electrician. Do not attempt to do it yourself.

Electricity and water don’t mix, which is why you’ll also have to get a ground fault circuit interrupter (GFCI) device installed between the hot tub and power source.

Moisture-resistant walls

Chlorine and other chemicals protect your hot tub from bacteria, but the chemicals don’t prevent the build-up outside the tub.

Excessive humidity combined with heat can cause outbreaks of mold, which is damaging to your health and your home.

Even with a fully functioning ventilation system (which we’ll get onto in a bit), the room is going to steam up, which means you might need to redo your walls.

Economical water-resistant options include cement walls, cedar lining, ceramic tiles, and special moisture-resistant drywall. If you’re budget stretches to it, you could also consider glass or marble.

Make sure that any furniture and other accessories are also resistant to humidity and water damage.

Filtration system

While a chlorine smell in an outdoor hot tub isn’t such a problem, the last thing you’re going to want is wafts of chlorine throughout your home.

The way to reduce the risk of a foul chlorine smell is to use a different system to sanitize your water.

Saltwater is an excellent choice for an indoor hot tub. With a proper water maintenance routine, saltwater systems have very little smell.

A saltwater spa is a very economical choice, but it is a bit of a learning curve. For something that’s odor-free and requires very little maintenance, consider the benefits of SilkBalance.

SilkBalance buffers the pH and alkalinity levels and eliminates the need for the frequent testing and adjustment of other chemicals.

Humidity control in a hot tub room

Steam is an inevitable part of owning an indoor hot tub. While keeping the room heated helps to reduce humidity and condensation levels, it isn’t enough.

Excessive moisture causes unpleasant odors and results in air-quality problems that affect your respiratory system. These issues can only be dealt with properly using a ventilation and dehumidifier system.


A powerful ventilation system is vital to pull the moist air out of the room while trapping the conditioned air. Powerful exhaust fans or forced air systems combat the damaging moisture that remains after using your hot tub.

Ventilation systems push out 10% more air than they pull in. This reduces the risk of creating a seal that traps moisture in the room.

A ventilation system installed along with the hot tub is crucial to controlling humidity and condensation indoors. Powerful exhaust fans or forced air systems can reduce the amount of heat and moisture remaining indoors after the hot tub has been used.


Dehumidifiers reduce the humidity levels in the area around the hot tub, preventing issues such as condensation and moisture absorption on the walls and floors.

Most modern dehumidifiers function similarly to full HVAC systems. They’re capable of both heating and cooling the air.

To offset the evaporation from the hot tub, the air blower inside the dehumidifier runs 24 hours a day, aided by the compressor which runs for 10 minutes at a time.

The air filters need to be replaced every month or two, and the dehumidifier needs regular maintenance by an HVAC specialist to ensure that it continues to function properly.

Open windows

If the room where your hot tub is installed has a window, it’s important to make use of it while the weather outside is warm.

If you live in a cold climate, however, it’s best to keep it closed.

Insulated cover

kw: Do you need a cover for an indoor hot tub?

It might seem pointless to use an insulated cover on an indoor hot tub, but they are definitely necessary. Not only do they save on heating costs, but they also trap in the dreaded moisture.

Combine your insulated cover with a floating spa blanketOpens in a new tab., and you’ll be able to enjoy the lowest possible levels of humidity.


Certain indoor plants thrive on moisture, absorbing it through their leaves. Having enough of the right plants can help improve the air quality inside your spa room.

Plants such as Peace lily, English ivy, parlor palm, Boston fern, and Tillandsia are all excellent choices. They look great, have a ton of health benefits, and leave the room feeling less sticky.

Joshua Milton

Joshua Milton is a seasoned hot tub enthusiast. With many years of experience in the industry, he offers valuable insights on hot tub maintenance, health benefits, and relaxation techniques.

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