December 12, 2022

No Exhaust Fan in the Bathroom? Here Are Alternatives.

So, we don't like to think about what happens in the bathroom. But business has to be done. And that business can become pretty unpleasant in a bathroom without an exhaust fan.

To make matters worse, the very act of freshening up creates humidity in the bathroom that, without the proper ventilation, will lead to mold growth and ceiling damage. So what should you do if your bathroom doesn't have proper ventilation?

There are a few key things you can do to keep bathrooms without an exhaust fan mold-free and smelling fresh:

  • Reduce humidity by taking cool showers
  • Remove damp towels and mats
  • Run a dehumidifier or space heater after showering
  • Run an air purifier to reduce mold spores and odors
  • Manually dry the shower and mirror after use

This article will cover how to use these methods effectively and also give you some additional tips for keeping a bathroom without ventilation in good shape.

Do Building Codes Require Exhaust Fans in Bathrooms?

Surprisingly, not all building codes require mechanical exhaust systems in bathrooms. Some municipal codes do require them, while others only recommend they be installed.

Section R303.3 of the International Building Code (last revised in 2018) states that "Bathrooms...shall be provided with aggregate glazing area in windows of not less than 3 square feet, one-half of which shall be openable. Exception: glazed areas shall not be required where artificial light and a local exhaust system are provided."

This can be interpreted to mean that the International Building Code does not require exhaust fans for bathrooms as long as the room has a window that will open.

Older homes built before standardized regulations may have bathrooms with no exhaust fans as well.

In areas that require bathroom fans to be installed, they typically call for a minimum CFM (cubic feet-per-minute) capacity of 50 CFM. For bathrooms larger than 50 square feet, professionals recommend a fan that has roughly the same CFM capacity as the square footage of your bathroom.  So an 8 x 10' bathroom would need an 80 CFM ventilation fan.

What Happens if a Bathroom Doesn't have Ventilation?

Without ventilation, bathrooms can become stuffy, smelly, and unpleasant to use. But excess moisture left in a bathroom can cause much bigger problems.

High humidity in your bathroom will make wallpaper wrinkle, paint peel, and wood fixtures swell. Since warm air can hold more moisture than cold air, and warm air also rises, excess moisture can create brown water stains on a drywall ceiling. In extreme cases, it's even caused ceilings to sag or collapse.

If water is heavy in the air, it will be absorbed by the wood, concrete tile grout, or other semi-porous materials in your bathroom. Anywhere that water is trapped, there's the potential for mold and mildew growth, which can lead to significant health problems.

Humidity Levels in a Bathroom

What does excess moisture mean, exactly? As a general rule, you want to keep your home between 30 and 50% relative humidity. This will keep your paint and drywall in good shape and mold and mildew at bay.

But what is relative humidity? Relative humidity refers to the amount of water that the air can hold. The exact amount of moisture in the air depends on the air's temperature.  The warmer the air, the more water it can hold.

So, if your bathroom is 80 degrees Fahrenheit and has 50% relative humidity, that means it's holding half of the water it could at that temperature. If you cool the air down to 60 degrees but don't remove any moisture, the relative humidity will increase to 67%.

You can use a hygrometer to measure the relative humidity in your bathroom.

When the air reaches 100% relative humidity, also known as the dew point, it cannot hold any more water and condensation will form on cold surfaces. So if you don't have an exhaust fan -- or you don't turn it on -- and your bathroom mirror fogs up while you shower, that means you've hit 100% relative humidity.

How to Ventilate a Bathroom Without a Fan

So if your bathroom doesn't have a fan, how can you ensure proper ventilation to protect against mold and preserve your bathroom aesthetic?

If you have a window, open it! Open the window before you shower, because it's more effective to prevent the room from reaching 100% humidity than to try to clear the moist air out afterward. Once condensation droplets form on mirrors, tiles, and other surfaces, they will begin to evaporate and elevate the humidity levels in the room.

However, sometimes opening a window won't help very much. If it's a hot and muggy day, you might let in nearly as much moisture as you send out. If it's a cold day in your area, letting cool air in may work against you, too. Cold air can't hold as much moisture as warm air, so you will hit the dew point faster in a cold room.

How to Ventilate a Bathroom Without Windows

Thankfully, there are some low-cost solutions for bathroom ventilation, even if you don't have a window to open.

Use a Bathroom Door with a Privacy Screen or Louver Slats

shower privacy screen

The usual advice for reducing humidity while you shower is to leave the bathroom door open. But who really wants to do that? If you live alone, maybe. But if you have roommates who you aren't that friendly with, you can compromise by installing a privacy screen or a slatted louver door on the bathroom. This will allow air exchange without impeding your privacy. Don't forget to leave the door completely open when you leave the room.

Run a Box Fan or Electric Heater in the Bathroom

modern bathroom electric heater

Running any kind of plug-in fan after you shower will move the humid air out and speed up the drying process in the bathroom. If you run a space heater with a fan, that will dry things out even faster. Just set a timer to remember to turn it off after 20 or 30 minutes.

Install a Recirculating Fan


A recirculating fan doesn't vent to the exterior. So even if it's installed in the ceiling or wall, it won't actually remove damp air from the bathroom. (It also probably won't meet building code.) But by keeping the air moving, an in-wall recirculating fan can help your bathroom dry more quickly.

It's critical to make sure that the drywall is fully sealed around the edges of the fan. If there are gaps between the wall and the fan, this will allow moisture into your attic or insulation, probably causing a bigger mold problem than it solves.

Any fans or additions to the HVAC system should be installed by a professional contractor.

How to Reduce Humidity in a Bathroom

Of course, the best way to prevent water damage in a bathroom without vents is to reduce the amount of accumulated moisture in the first place.

Shorter, Cooler Showers

"Shorter, cooler showers" isn't anyone's favorite mantra. But taking quick, cold showers will reduce your energy bill and the level of steam in your bathroom. Cold showers equal less steam, which equals less condensation and water damage.

Wipe the Shower Walls Dry

Even if you do have an exhaust fan in the bathroom, it's great to develop the habit of manually removing any lingering water after you shower.

Use a towel to soak up puddles in the shower stall or on the bathroom floor.

Also see: What bathroom flooring options should you choose

Wipe the shower walls down with a squeegee and dry off the shower mirror, tile grout, and any other areas where there's condensation.

After drying these surfaces, be sure to remove your bath towels, bath mat, and any wet clothing from the bathroom. If you don't, the moisture in these linens will evaporate right back into the air. They may also become breeding grounds for mildew.

Close the Shower Curtain after Use

After you shower, draw the curtain all the way closed so it's flat and will dry more quickly. Avoid any folds that could trap moisture. Wash the shower curtain frequently to stop pink mildew growth in its tracks.

Run a Dehumidifier

Dehumidifiers pull humidity from the air by condensing water on a very cold coil. The machine collects water in a reservoir, which you can empty as needed. It does take energy to run, but a dehumidifier is one of the most effective ways to reduce moisture buildup in a bathroom and prevent damage.

You can also purchase dehumidifying units that use silica gel pads to absorb airborne moisture.

Use Dehumidifying Crystals

Placing a bowl of DampRid or similar humidity-absorbing crystals won't fully solve your bathroom ventilation problems. But it can do a small part in keeping the humidity levels down in a bathroom without an exhaust fan.

Moisture-loving Houseplants

Carefully chosen houseplants can reduce carbon dioxide in the bathroom and even draw moisture out of the air. Boston Fern, Green Pothos, Epiphyte orchids, and pennywort are examples of beneficial plants for bathrooms.

Don't choose houseplants that need to be watered frequently for the bathroom. A pot of wet soil will release water into the air and potentially make your moisture problem worse.

Not recommended: Heated Mirrors

De-fogging mirrors are convenient if you want to put your makeup on right after a shower, but they won’t help the humidity problem. These mirrors are heated so that water cannot condense on them. Heating the mirror won't reduce the amount of water in the air -- it just won't give the water an obvious place to land.

It's better to let the water condense on the mirror and remove it with a squeegee than leave it hanging out in the air of the bathroom, or condensing on a harder-to-reach spot, like the tile along an exterior wall.

How to Prevent Mold and Mildew in a Bathroom With No Fan

Without ventilation, a bathroom can become a prime breeding ground for household black mold (Aspergillus niger) or pink mildew (Serratia marcescens, actually a bacteria). These unsightly growths thrive in wet areas with low air circulation, between 60 and 80 degrees Fahrenheit. Mold isn’t only unpleasant to look at; it can be dangerous. Mold can trigger allergies and exacerbate respiratory disease.

Thankfully, if you’re proactive about preventing mold and mildew growth, it can be kept to a minimum, even in a bathroom with no exhaust fan.  Here are our top tips for preventing mold from taking hold: 

Run an Air Purifier in the Bathroom

air purifier in white

An air purifier isn't a substitute for a fan or a window in the bathroom. It won't increase the ventilation, but it is a highly-effective tool for keeping your bathroom air fresh. A top-quality air purifier with a HEPA filter will remove mold spores from the air in the bathroom and reduce odors.

Clean the Shower Frequently

If you don't have an exhaust fan, it's essential to clean the shower frequently and zap those mold spores before they have a chance to settle in.

For best results, wipe down the sink, toilet, and counters with a disinfecting cleaner daily.

Seal the Grout on Your Tile

Concrete grout is porous and will absorb humidity. This means it can incubate mold in an area that's essentially impossible to clean. You can prevent nasties from growing between your tiles by sealing the grout with a spray-on or silicone sealant.

Use a Shower Dome

shower dome example

A shower dome is essentially a rounded plastic roof over your shower. It won't reduce the amount of steam released into the air, but it can contain it to some degree. The more the water is contained in the shower area, the easier it will be to wipe it away after you're done.


There are definite challenges to keeping a bathroom without an exhaust fan clean, fresh, and mold-free. Especially when this isn't originally planned in your bathroom renovation plan. But by keeping an eye on the humidity level in the bathroom and making an effort to mop up excess water and provide supplemental ventilation, you can create a healthy environment in any bathroom.

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Written by


An interior design professional with a Master's degree in Architecture and 14 years of practical experience.
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