How Do You Prevent Mold in a Sauna? (With an Easy Cleaning Regimen!)

Mold doesn’t discriminate. It likes any environment with high moisture, low light, and organic materials. If not properly maintained, a sauna is a perfect spot for a mold party – so, is there a way to keep this from happening?

The best way to remove mold in a sauna is to create a regular cleaning regimen that includes removing all items and accessories from the sauna, sweeping it out, scrubbing with soapy water, and letting it air dry. Keeping the sauna dry in between uses helps cleaning last long and prevent mold from growing again.

We now know of the ways to prevent mold growth, but how exactly does it work? Read on to find out!

What is Mold, and How Does it Grow?

Mold is an airborne fungus. It grows on organic materials such as wood and textiles, although mold can also grow in the soil or on foods. It feeds on these substances as it grows, and with heat, darkness, and lack of circulation, it thrives. 

Mold reproduces by releasing spores that attach to a nearby surface or float through the air until they find an area suitable for growing. Mold growth will happen faster when it’s warm and moist, which is why it’s so important to take preventative measures for your sauna.

If you’re in an enclosed space with stagnant or insufficient ventilation, the mold will quickly spread over any surface it comes into contact with. This can cause all sorts of health problems as airborne spores are released into unprotected spaces where people may breathe them in, such as the sauna.

Don’t worry too much, though – there are many ways to prevent unwanted mold growth in your sauna, which will be discussed in detail.

Why does mold grow in the sauna?

Your sauna has a lot of heat, moisture, and dark surfaces. This combination is perfect for mold and other fungi. If you don’t take precautions now to prevent mold growth, it will spread quickly and may require you to replace your entire sauna setup.

Mold can grow in less than three days when left unchecked in your sauna, and its spores can be carried in the air through tracking or ventilation systems. Mold infestation is considered a  serious health risk. 

Mold can spread quickly and easily, making it difficult to control. It also poses a significant threat to the respiratory system and should not be left unchecked. 

Mold on wood in the sauna

Mold likes to grow on organic material, which is why wood and other similar materials in the sauna’s environment are susceptible to mold. The best way to tell if a sauna has a mold problem is by looking for signs of obvious water damage such as peeling paint, wet spots, or cracks in the ceiling.

Aside from these signs of visible water damage, look out for discoloration on the roof boards and wood beams inside. Another way to check is by using an electronic moisture meter that will quickly give you an accurate reading of relative humidity levels inside your sauna. Keeping a relative humidity of below 60% can prevent most mold issues quite well.

Wood can be especially tricky when it comes to preventing and removing mold. It’s a porous material, giving the mold a place to hide from a good scrub down.

 Wood can soak up moisture, too – so all around, it provides a nice little home to funguses like mold. That is why it’s so important to take preventative precautions instead of waiting until there are visible signs of a mold issue.

Mold on plastic in the sauna

Mold that grows on plastic can be frustrating because it is difficult to remove and smells terrible.

It can grow on just about anything, including plastic. When mold grows plastic, it can penetrate the surface and leave permanent stains that are unfixable short of buying new material. It can also make the plastic brittle and break easily.

One of the most common molds that grow on plastic is called “serratia Marcescens”. It forms a pink slime and is very common in damp areas such as bathtubs and showers. And it’s not even a mold at all – it’s a bacteria! It usually isn’t dangerous for people with a healthy immune system.

Fortunately, it’s also very easy to remove. Just a quick scrub with some soap or other chemicals will take care of it. And, because plastic isn’t an organic substance, mold and other microorganisms can’t use it as a food source – which means it won’t grow quite as easily.

This is why a sauna shouldn’t have any food or drink (besides water) nearby – mold won’t grow quite as readily if it doesn’t have anything to feed on.

Mold on metal in the sauna

Mold can grow on just about anything, including metal – as long as it has a food source. Fortunately, if caught early enough, it’s straightforward to clean and prevent further mold growth.

While the effects of mold are usually limited to the appearance, metal can also corrode and change shape when it comes into contact with moisture. In order to prevent this, it is essential not to leave damp clothes or towels lying around near metals that are prone to corrosion, such as copper and iron.

Now, how do we clean off mold that has already taken hold?

How to clean mold in a sauna

As soon as you notice any signs of mold, it’s imperative to act quickly and remove the source. Mold can form in a sauna if the room is not properly ventilated or there are leaks and water infiltration. The best way to remove mold from a sauna is through regular cleaning with bleach-based products followed by scrubbing with scouring pads under running water.

Remove any towels, seats, or other accessories from the sauna

Start by removing any removable items from the sauna. This includes seats, benches, steamer baskets, and other accessories. If it is safe to do so, you may also remove the walls of the sauna. Remove everything you can possibly think of from the sauna. You don’t want to miss anything that might give the mold a place to hide and come back. 

Removing these items will make cleaning more manageable because it will improve your visibility inside the sauna – you’ll be able to see what needs a wipe down with lemon juice, bleach, or vinegar and do a much more thorough job.

For good measure, vacuum out the floor and wipe down anything that may have been touched by water, including the walls, if there’s a chance that they’ve been sprayed with water.

Sweep out the floor of the sauna

This will help to remove any mold spores that have been tracked in, and prevent them from growing into another mold problem down the road. It will also remove dirt and debris, which will allow for much more thorough cleaning of the environment.

It may sounds counterintuitive for those who clean the floor last in their household chores, but you should sweep before you clean anything else. This is because mold spores are very light and airy, so any bit of dust or air that’s kicked up can lift the mold onto a more viable surface, such as a wooden bench or towel rack. 

In this way, when it comes time to scrub the walls, you will know that there won’t be new mold spores deposited on the surface you just worked so hard to clean!

3 – Scrub the seats, walls, and floors with soapy water

There are many different ways you can choose to actually clean the mold.

Soapy water is a good choice because it helps to strip away and dissolve dirt and grime, including mold. It’s a good, eco-friendly way to clean the mold without harsh chemicals.

Vinegar is another good choice. The acidity is too harsh for mold to survive in, plus it helps with odors. You may find that these more natural cleaners will remove most of the dirt while leaving behind some residue without giving off fumes or having any poisonous qualities associated with them.

It would also be wise not to use any other ingredients to make the solution stronger since even if those items were once harmless separately, they might react differently when mixed together. They could cause adverse effects on your health when contacted at close range (such as breathing). Never mix any household chemicals with anything unless the instructions explicitly say to do so. 

If that doesn’t sound appealing to you, perhaps it’s time to break out the big guns – good old-fashioned bleach! It’s a tried and true way of killing and removing mold. Simply fill up a bucket with bleach water and use it to dip the cloth or sponge you’re using in.

If you must use bleach, be sure that the sauna and area around it are properly ventilated, this will prevent any health issues that could arise from exposure to the noxious fumes.

Let the sauna air out

We don’t want all of that hard work to be for nothing! Once you have scrubbed and removed the mold and rinsed the area from harsh chemicals, this next step is crucial.

You must leave the door open and air the sauna out until everything is completely dry – all it takes is one mold spore finding a damp area that stayed damp because there was no airflow. So, be sure to keep that environment as inhospitable for mold as possible!

How to prevent mold in the sauna

The basic formula for this is to remove the elements of the environment that mold thrives in. 


Use a dehumidifier to prevent humidity from rising above 60%, or even just keep the door propped open when the sauna isn’t in use. All it needs is a little airflow!


Most pathogenic microorganisms thrive in environments that are about as hot as body temperature. If you keep the temperature of the sauna turned up high above 104°F, you can keep most fungi from growing. You could also freeze the microorganisms out by bringing the temperature below 64 °F.


Mold thrives without light, partially because it keeps the humidity high and also because dark spaces are often not well ventilated. Turn on the lights in your sauna, prop the door open, and you can even get a special lamp that can kill and prevent mold growth. 

Food sources

Aside from plain water, never bring anything to eat or drink into a sauna with you. Mold will feed on just about anything and grow on any surface that the food particles remain on. Without a food resource, mold cannot grow – so let’s not give it a chance.