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Do You Need a Fan in a Bathroom With a Window?

Hopping out of a nice steamy shower feels refreshing, but it creates an abundance of condensation in your bathroom. You can always open the window to let the steam out, but it’s hard not to wonder whether a fan would do a better job. So, is installing an exhaust fan in your bathroom necessary?

You do not need a fan in a bathroom with a window, but it is recommended for proper bathroom ventilation. Exhaust fans remove the excess moisture in your bathroom more efficiently than an open window alone.

In this article, I will deep dive into the window vs. fan ventilation in the bathroom debate and explain what happens when there isn’t proper ventilation. I’ll also cover how to install an exhaust fan and when to use it. Let’s get started.

Window vs. Fan Bathroom Ventilation

Ventilation is necessary for your bathroom to prevent mold and provide sufficient airflow. The question is, does a window give as much ventilation as a fan?

Well, no. Windows and fans offer different levels of bathroom ventilation.

Bathroom exhaust and supply fans move the air from inside outside and push the air from outside inside. This cycle improves the airflow in your bathroom and provides the best ventilation. Some fans even filter the air.

Windows aren’t as comprehensive. They provide decent airflow and fresh air, but the level of ventilation your bathroom gets depends on factors such as wind, how much air your home traps, window location, etc.

Read: Attic Fan Vs. Whole House Fan

Should There Be Vents in Windows?

Vents in windows are a great way to keep excess moisture and condensation at bay. Windows with vents are called trickle vents. They allow for ventilation throughout your bathroom without opening the window, which is especially great for the wintertime, or if your window points to the road.

What Is the Code for Bathroom Ventilation?

The bathroom ventilation code states that the exhaust fan should lead directly outside. Regarding window functionality, your bathroom must have a window that opens. Also, the window opening should be at least 3 square feet (.28 square meters).

Read: How To Fix A Noisy Bathroom Fan?

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Is It Against Code Not To Have a Fan in the Bathroom?

It is not against code to not have a fan in your bathroom, but it is preferable to have one. Bathroom fans circulate the air throughout your bathroom better than a window alone. However, it is not necessary to install an exhaust fan if there is a window.

Ensure that your window area meets building code, and you won’t run into trouble with building inspectors for lacking a fan in the bathroom.

What Do You Do If Your Bathroom Doesn’t Have an Exhaust Fan?

If your bathroom has no exhaust fan, open the bathroom window or install one. If your bathroom does not have a window, you must install a fan. Either way, ventilating your bathroom is a requirement according to the building code.

Best Windows for Ventilation

If adding a fan to your bathroom isn’t the route you want to take, you should maximize the ventilation you get from your windows by choosing the best option you can get for this purpose.

 Here are the types of windows that offer the best ventilation:

  • Bay Windows. Bay windows may be more common in master bathrooms. These combine three different window panels, and the two side windows often open up for double the air circulation. The most significant benefit of bay windows is they can catch two directions from the wind rather than one.
  • Casement Windows. Casement windows open out rather than slide up and down, which allows you to control the level of ventilation in your bathroom. You can also easily keep the curtains drawn for more privacy with your airflow.
  • Sliding Windows. Sliding windows open to the side rather than up and down. This motion allows for better top to bottom ventilation. Plus, they work with a variety of different window styles.
  • Double-Hung Windows. Double-hung windows offer a lot of different movement options. They slide up and down and open out like a door. This window style allows you to control the amount of ventilation you need.

Read: 3 Reasons Why Water Is Dripping From The Bathroom Fan

Signs Your Window Isn’t Enough Ventilation

Taking your daily shower raises the humidity in your bathroom, and it’s easy for excess moisture to build up. If your bathroom doesn’t get enough ventilation, you could face some unforeseen consequences that may include:

Mold and Mildew

Mold grows in moist environments, so your bathroom can become its playground if the excess moisture sits there. Mold grows on wallpaper, paint, wood, and drywall—all of which can be featured in a bathroom.

The CDC lists bathroom exhaust fans as a way to prevent a buildup of mold in your bathroom. They help lower the humidity level after a shower or hot bath, discouraging mold growth.

Mildew is flat clumps of mold that grows in the same conditions as mold. The biggest difference is that mildew lives on shower walls and window sills, while mold makes its home on the actual bathroom walls, ceilings, or carpet.

Peeling Wallpaper or Damp Spots

The extra moisture in your bathroom can build up on your wallpaper (which is how mold grows) and cause the adhesive to loosen, causing it to peel off. It can also leave unsightly damp spots on your bathroom walls.

If you notice peeling or damp spots in your wallpaper, you may need to upgrade the ventilation system in your bathroom.

Weakened Structural Integrity

Over time, the extra humidity in your bathroom and moisture buildup can cause structural problems in your home. Mold growth isn’t the only potential consequence of raised bathroom humidity. There is also a potential for your drywall to weaken and damage your wood.

If you notice this damage, you may want to consider installing an exhaust fan.

Read: How To Save Heat In An Apartment?

How To Install An Exhaust Fan In Your Bathroom?

Installing an exhaust fan in your bathroom is a project you can do yourself. Here’s how to go about it:

  1. Size the fan you are about to install and mark where you need to cut.
  2. Using a saw, cut a hole the size of your fan onto the wall or ceiling.
  3. Attach the fan using a drill and screws.
  4. Head to the roof.
  5. Cut a hole in the roof that will fit your vent and tailpipe.
  6. Using roofing nails and cement, install the roof portion of your vent.
  7. Connect the two vents with a wire.
  8. Follow the instructions that came with your exhaust fan to wire the switch.
  9. Test out your new bathroom fan.

If you’re not good with your hands, there’s no shame here. Calling a professional could streamline the process and ensure there aren’t any issues with the installation. It should cost anywhere between 100 and 600 dollars (95–570 euros), depending on where you live and the difficulty of the project.

If you insist on taking the DIY route, be sure to keep the following FAQs in mind:

Where Should Bathroom Vents Go?

Bathroom vents should follow the source of moisture in your bathroom: that would be your bathtub or shower. Placing your vent here gives steam and water vapor an easy avenue to escape and filter outdoors.

Do Bathroom Exhaust Fans Need To Be Vented Outside?

Bathroom fans need to be vented outside to circulate fresh air into the bathroom. Be careful where your vent flows because it may pull in polluted air, especially if it filters through an attic or basement. Spaces like those are home to mold and other harmful fungi.

When To Turn On the Exhaust Fan?

Most people turn on the bathroom fan after a shower to clear the steam, but the best time to turn on your bathroom’s exhaust fan is before you bathe. You should also leave it on 15 to 20 minutes after your shower to ensure you clear out the extra moisture and reduce the humidity level.

It’s the same thing with your bathroom window. If you don’t have a fan, open the window before a shower, and leave it open until the moisture subsides.

Read: Why Is Indoor Air Quality Important?


A bathroom exhaust or supply fan provides better ventilation than a bathroom window. If you only have a window in your bathroom, you can still size and position it to maximize the ventilation it offers.

Adding a fan to your bathroom could drastically limit the amount of mold, mildew, and structural changes to your bathroom. Installing one is a project you could DIY or hire a contractor to complete. No matter how you ventilate, be sure to circulate the air until that moisture has subsided