How To Vent A Bathroom Without A Window

An internal bathroom without windows is more common than you think. It can be frustrating to deal with since it leads to moisture buildup, odor, and mold infestation. To remedy the lack of sunlight, here are a few tried and tested methods to ventilate a windowless bathroom properly. Whether you plan to improve, build, or renovate the washroom, this guide will be a godsend.


It’s crucial that your bathroom has some type of ventilation to remove unwanted wetness and maintain a healthy climate in a bathroom. With no moving air, the buildup of moisture can damage the walls and promotes the growth of mold microorganisms. Not to mention the nauseating, dank, musty smell that will affect your health. 

1. Install An Exhaust/ Ventilation Fan

 A central exhaust fan is a space-saving and cost-effective solution for circulating clean, fresh air in an internal bathroom without windows. The motor fan will pull excess moisture out through the ventilation pipes, so your bathroom air remains dry and odor-free, with no mold pathogens to worry about. It also reduces the risk of rust and decay in a windowless bathroom. Most exhaust fans will run automatically every time you switch on the light.

The bigger the fan, the quicker moisture will be removed. There are a few types of exhaust fans in the market. We recommend getting a ceiling exhaust fan because it is inexpensive and conceal from eyesight. A wall exhaust fan is typically more powerful but can be loud and tricky to install.

The drawbacks of the exhaust fan are the expensive installation and heat deduction. Some hacking and drilling are needed, and you might need to hire a professional for the task. Some buildings and apartments might restrict you from installing one because it is not part of the building code (DIN 18017 standard). If you live in a rented place, you must discuss this with your landlord.

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2. Get A Dehumidifier

The perfect home appliance for a windowless bathroom, particularly in rented accommodation. A dehumidifier drains excess moisture in the bathroom by collecting the water vapor into the reservoir or straight to a floor drain through condensation. It keeps the air dry and much more breathable. Unlike an exhaust fan, no installation is required as a dehumidifier will work straight out of the box. Best of all, it is inexpensive, where you can get a 22-pint/ 30-pint dehumidifier for under $200.

Refrigerant and desiccant are the 2 most common types of dehumidifiers used in an internal bathroom. While desiccant is much more convenient due to its smaller size, only go with an electric refrigerant dehumidifier due to its higher moisture-holding capacity.

The downside of a dehumidifier is its bulkiness. You will unlikely have the space to place it in the bathroom and keep it from getting wet, especially after a hot, steamy shower. It will most likely be left outside, which can be cumbersome in a small room. Then there is the hassle of turning it on every time you hit the shower and empty the water tank. A dehumidifier also does not have any air exchange like an air purifier. The motor noise is also deafening loud to the point you would choose not to use it.

3. Wipe And Mop

Simple as it may seem, wiping and mopping after a shower helps keep the dampness level down, especially in a bathroom with no windows. It removes the generated water droplets that would otherwise evaporate and increases the bathroom’s humidity level. All you need is a dry rag/ cloth and a mop to get started. Wipe thoroughly on fogged mirrors, tiles, bathtub, and basin. Repeat the steps until all splashes of water are removed. Spray disinfection to remove mold patches when spotted at first sight. While the entire process is tedious, it can prevent mold growth and will not cost you a dime.

4. Do Not Hang Towels Inside The Bathroom

A small change makes a big difference. Avoid leaving a wet towel inside a bathroom with no windows. Instead, dry the wet towels outside over the radiator and change the towels weekly. A damp towel holds a tremendous amount of water that will evaporate and adds dampness back to the air. The humid air remains stale with no place to air out, creating the ideal environment for mold and mildew to grow.

5. Leave The Bathroom Door To Create A Draught

Another simple yet often neglected step. Always keep the bathroom open, especially after a hot shower. Doing so creates a draught that increases air circulation and allows trapped humid air to flow out. You will see a tremendous drop in dampness in the bathroom compared to a closed door. While you’re at it, make sure the shower curtain is folded to reduce any airflow obstruction. For better results, use a hydrometer to check the level of air humidity in the bathroom.

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6. Use An Air Purifier

The next best ventilation tool. An air purifier can help circulate clean air and reduce mold spores buildup in a windowless bathroom with poor ventilation. It complements a dehumidifier that lacks air exchange by removing airborne pollutants that will affect humidity and foul odors. You can get a compact air purifier and place it next to the basin (Just make sure not to get it wet).

While an air purifier effectively moves air, it is not a necessity as a dehumidifier. It cannot remove moisture collected in the bathroom. The filter also requires regular replacement, which adds up to the cost. If you already have an air purifier in the room, there is no need to get an additional unit.

7. Use A Disposable Moisture Absorber (Quick Fix)

For a quick and temporary solution, plenty of moisture absorbers like Damprid and Dri-Z-Air can help with humidity issues in a windowless bathroom. Most moisture absorbers come in a small container bag filled with calcium chloride crystals or silica gel. It fits nicely in small spaces; some even come with a scented fragrance that can mask any musty odor. Just hang the moisture absorber by the toilet handle or leave it at the basin table. Replace them according to the interval time (30-90 days).

The biggest issue with a moisture absorber is its usefulness. It is not as effective as a dehumidifier in removing moisture; not even close. The crystals will fill up quickly, and you will need to replace them promptly. While a moisture absorber is relatively cheap (between $1-5), you will need multiple packs to see a difference, and the cost will stack up exponentially. Consider this as a last resort.

How To Vent A Bathroom Without A Window

Final Thoughts

We hope this guide will solve the humidity issues in your windowless bathroom or basement for good. As simple as some of the method sounds, it is proven effective in ventilating a bathroom and keeping mold away. Feel free to mix and match a few of the above methods to help your situation. If you are planning to build a new bathroom, always include windows in the design layout for better sunlight and climate.

Max Fernandez

A loving father and a dedicated reviewer for airfuji.com with more than 1000 air purifiers under his belt. Max Fernandez is also one of the million patients currently suffering from asthma. Feel free to nudge him if you have any questions.
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