How To Ventilate A Bathroom Without Windows

How To Ventilate A Bathroom Without Windows

So you’ve got a bathroom without windows? That used to be no big deal back in the day. But nowadays we know better – proper ventilation is crucial for a healthy home.

Trapped moisture and stagnant air in an unventilated bathroom basically creates a perfect environment for mold, mildew, and bacteria to thrive. Not to mention the smells! No one wants to walk into a smelly, humid bathroom first thing in the morning.

Luckily, there are plenty of ways to ventilate a windowless bathroom. With a little effort, you can keep your bathroom fresh and moisturize-free without having to knock down walls to add a window. Let’s go over some of the best techniques.

Install an Exhaust Fan

An exhaust fan is the #1 method recommended by experts for ventilating a bathroom without windows.

Centrally Ducted vs Wall-Mounted

For bathrooms with an exterior wall, a centrally ducted exhaust fan is ideal. This type of fan mounts on the outside wall and vents air directly outdoors via a duct running through the wall.

For fully interior bathrooms, a wall-mounted or ductless exhaust fan is better. These fans mount on the wall inside the bathroom and connect to vents that channel the air through ductwork in walls, ceilings, or soffits until it reaches the outdoors.

Choose the Right CFM

You’ll want an exhaust fan with the proper CFM rating (cubic feet per minute of airflow) for the size of your bathroom. Generally, a small half bath needs about 50 CFM, while a master bathroom over 100 square feet will need 100 CFM or more. Oversized is better than undersized for maximum air circulation.

Placement Matters

Mount the exhaust fan high on the wall or ceiling above the shower or bathtub so it can effectively capture the warm steam.

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DIY vs Pro Install

Installing a bathroom exhaust fan isn’t too hard if you’re handy, but for some ducted fans, it’s wise to hire a professional electrician and heating/cooling pro to ensure it’s set up correctly.

Dehumidifier to the Rescue

A dehumidifier is your second best option for pulling moisture from the air in a stuffy windowless bathroom.

Portable vs Wall-Mounted

Portable dehumidifiers are an affordable option and easier to install – just plug it in and set in a corner on the floor away from the shower area. However, wall-mounted dehumidifiers take up zero floor space and often come with a handy auto-sensing humidity function.

Continuous vs Auto-Sensing Mode

Some dehumidifiers run continuously at a set level. For bathrooms, an auto-sensing model that turns on when humidity rises is ideal so it’s not running 24/7.

Pro Tip: Empty the Tank

Remember to empty the water tank regularly, or the water overflow can lead to mold growth! Setup is minimal – just keep it away from direct shower moisture and find a nearby outlet.

Get Crafty with Cross-Ventilation

Creating cross-ventilation is a clever hack for pulling fresh air through a windowless bathroom.

Utilize Adjoining Rooms

Open the bathroom door, as well as windows and doors in any rooms connected to the bathroom. Position a fan near the bathroom doorway angled to direct humid air out towards the open windows. The negative air pressure created naturally pulls fresh air into the bathroom from outside.

Doorway Louvres

For cross-ventilation to work optimally, you may need to install louvred vents in the upper portion of the bathroom door to allow better airflow.

Monitor Humidity

Use a humidity monitor to determine when moisture levels are too high, signaling it’s time to run fans and open up for ventilation. Once humidity drops below 50%, you can shut the makeshift system down.

DIY Moisture Removal

A few minutes of good ol’ elbow grease post-shower can also help remove lingering moisture.

Squeegee Power

After showering, wipe down walls, mirrors, and shower doors/curtains using a squeegee or towel to soak up water droplets before they evaporate into humidity.

Leave Shower Doors Open

Always leave glass shower doors completely open or slide shower curtains to the far side until fully dry after use. This allows moisture to escape rather than being trapped.

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Use Absorbent Floor Mats

Placing absorbent cotton mats on floors or bathroom vanity/sink surfaces soaks up excess moisture from dripping wet bodies. Don’t forget to launder mats regularly to prevent mold growth.

Limit Towel-Drying In Bathroom

Avoid leaving damp towels hanging to dry inside the humid bathroom itself. Take towels to a ventilated room or use a clothes dryer.

Plants Purify Humid Air

It may sound surprising, but certain houseplants can help remove moisture and freshen stale air.

Moisture-Absorbing Varieties

Plants like ferns, orchids, palms, and bromeliads are effective at absorbing ambient moisture through their leaves and soil.

Low Light Houseplants

Since windows are scarce, choose low-light houseplants that tolerate dark bathrooms like pothos, Chinese evergreen, peace lilies, and of course, mold-resistant orchids.

Avoid Overwatering

Overwatering plants raises humidity. Use gravel trays and space plants apart to allow airflow and prevent mold from forming in damp topsoil.

Tips to Prevent Mold & Mildew Growth

Ventilation helps, but you’ll need to take extra steps to prevent mold from gaining a foothold in a humid bathroom.

  • Use mold-resistant paints and caulking around tubs, sinks, windows and other surfaces prone to moisture damage.
  • Ensure your bathroom has proper insulation and sealing. Any leaks or drafts make controlling humidity much harder.
  • Run exhaust fans for at least 45 minutes after showering or bathing to remove lingering moisture, not just during.
  • After showering, squeegee down walls and shower enclosures, then leave doors open to dry.
  • Make wiping down surfaces a daily habit to remove condensation and water droplets before they can feed mold.

FAQs About Ventilating a Windowless Bathroom

Is a bathroom without a window up to code?

Typically no, building codes require some form of ventilation, whether natural from a window or mechanical like an exhaust fan. Check your local regulations.

What’s the ideal humidity level for a bathroom?

Ideally keep bathroom humidity between 50-70%. Above 70% for prolonged periods risks mold growth.

How long should you run a bathroom exhaust fan?

Run the bathroom fan for at least 45 minutes after showering or bathing to fully clear moisture, not just while actively showering.

Where’s the best location to install a bathroom exhaust fan?

Install the exhaust fan high on the wall or ceiling above the shower/tub area to capture the maximal amount of warm, moist air.

Can plants really help remove moisture from the air?

Yes! Many tropical plants are adapted to absorb ambient moisture through their leaves and soil. But avoid overwatering plants, which increases humidity.


Ventilating a bathroom without windows takes a bit more creativity and diligence. But with the right combination of exhaust fans, dehumidifiers, cross-ventilation, moisture removal tips, and mold-prevention habits, you can keep the air fresh and prevent problematic mold and mildew growth.

The key is attacking humidity from multiple angles – actively venting air out, preventing excess moisture in the first place, and regularly eliminating what moisture does accumulate. With the techniques above, you’ll be breathing easy in your windowless bathroom in no time!

How To Ventilate A Bathroom Without Windows
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