Can Bathroom Exhaust Fan Be Installed in a Shower?


So your newly built or renovated bathroom is almost complete, and all that’s left is the exhaust fan. If you are wondering if it is okay to install the bathroom exhaust fan inside the shower, then you’re in luck. Here is what we know about exhaust fans in the shower.

You can install a bathroom exhaust fan in a shower. However, this is only advisable if the electrical wiring into the bathroom is connected to a Ground Fault Circuit Interrupter (GFCI) for protection, and that the fan itself is rated for bathroom showers.

What’s Ground Fault Circuit Interrupter Protection?

A Ground Fault Circuit Interrupter, often abbreviated as a GFCI, is an electrical device designed to protect people from the threat of electrical shock. When it detects an imbalance of electrical current in the system, it de-energizes it in milliseconds. This is crucially lifesaving in instances such as the contact between electricity and water, which could be fatal in a shower with an exhaust fan in it. Read my article about GFCI If you wish to learn more.

What Does It Mean for an Exhaust Fan to Be Shower Rated?

Of course, you can’t just install any exhaust fan into your bathroom. You must always check to ensure that it is shower rated.

What this means is that the manufacturer has deemed (rated) it appropriate for use in a bathroom setting. A shower rated fan has been manufactured specifically for safe use in an environment where it is highly likely to come into contact with water and is safer to use compared to a regular exhaust fan.

Always check the manufacturer specifications to see an indication of the fan as being shower rated to avoid possible accidents after installation.

Can an Exhaust Fan Be Installed in A Shower That Isn’t GFCI Protected?

Perhaps yours is an old home, and the circuitry running through the bathroom is not GFCI protected. Maybe the bathroom doesn’t even have a ceiling exhaust fan, but you’re looking to have one installed with its renovation. Is this installation possible?

You cannot install a bathroom exhaust fan in a shower if the circuitry isn’t the GFCI protected. This is because of the high electrocution risk.

It is for this reason that the US National Electrical Code (NEC) was updated in 1971 to require GFCI protection in most areas of a household with possible easy contact between water and electricity, including swimming pools, garages, kitchens and you guessed it, bathrooms. Read more about the code requirements here.

What’s The Best Position to Install a Bathroom Fan?

With all the requirements for the fan rating and electrical circuitry met, understanding where to best position your bathroom exhaust fan is the next most crucial decision since it determines the fan’s effectiveness. Here are a few things to understand before beginning installation.

The flow of hot, moist air

Remember that the point of a bathroom exhaust fan is to guide the warm moist air out of the bathroom so that it doesn’t settle on surfaces and develop into mold later on. A bathroom fan is the most effective way to prevent mold in the bathroom.

For this, it is important to understand how the hot moist air flows inside your bathroom every time you take a hot shower.

Hot air rises, so it will always move upwards, carrying the moisture along with it. With this in mind, it makes the most common sense to position your bathroom fan right on top of the hot air source. This is definitely in the ceiling, which could be either right above the shower or bathtub if it is there.

So what happens when you have both a shower and bathtub in the same room?

The rule of thumb to always go by is that hot air rises, so no matter where you decide to position your bathroom exhaust fan, it needs to be in the ceiling. This is where the hot moist air will end up, so this is where the fan should be. If your shower and bathtub are installed in separate positions, then the best installation point is in the ceiling between the two fixtures.

Remember that the running fan will automatically draw the hot moist air to itself, so having it in the ceiling is the first step to directing the moist air up and out of the home.

The ducting route to take

Positioning your ceiling fan is only half of the work done to properly ventilate your bathroom. If the hot wet air is going to go up and into your fan, then it needs to be directed out properly.

This is where the proper routing of the duct hose connecting the fan to the outside becomes incredibly important. Be sure to position it straight, whether it’s venting up out of the roof or across the attic through to the soffit.

Make the distance that the hot moist air needs to travel through as short as possible, to reduce the chances of condensation forming in the duct and to also not undermine the effectiveness of the fan.

Things to Keep in Mind When Choosing the Position

Your fan duct hose is probably going to run through the attic to the outside. There are a few things you need to make sure of before doing this.

  • First, make sure that there’s enough room for the upper end of the exhaust fan on the part of the ceiling you’ve selected, preferably between two ceiling joists.
  • Secondly, check for possible obstructions to the straight positioning of the duct pipe along the wall. You don’t want interruptions to this straight movement, so obstructions like chimneys, skylights, and more will probably need you to position your fan somewhere else.
  • This should be obvious but be thorough and meticulous in your installation to avoid any leaks that could result in hot humid air blowing into your attic and developing into mold.

What If I Have a Window In My Bathroom?

It’s a given that an exhaust fan is required in a bathroom where there is no ventilation, but what if your bathroom has plenty of it already? This is especially a practice for plenty of modern homes that are built today, with large windows that can be opened up to release the hot moist air.

Windows are integral for ventilating your home, but let’s face it. You won’t always be able to crack open a window when you are done with your shower. Imagine opening a window when it is snowing outside.

You probably should install a bathroom exhaust fan in your bathroom even if there are windows.

During this time, opening up the windows to let hot air out does more harm than good because you’d only be letting in dangerously cold air. In this situation, wouldn’t it be great to have a bathroom exhaust fan installed instead?

Check out my article about bathroom ventilation codes. There I discovered that bathroom fan is actually not always required by building codes.

How Long Should the Bathroom Fan Be Left On After a Shower?

It can be very easy to forget about a bathroom fan that you turned on while you were entering the bath. Some people even end up leaving it on all night after an evening shower, either forgetfully or intentionally, to “remove all odors in the bath completely.” This is a very dangerous practice!

Leaving your bathroom fan that is not rated for continuous use on for far too long is risky because it could end up causing fires, as the U.S. Consumer Product Safety Commission (CPSC) notes here.

After you have finished enjoying your relaxing shower it is recommended by the Home Ventilating Institute to keep the bathroom fan on for a minimum of 20 minutes after the shower, provided you have a correctly sized fan.

However this is the absolute minimum, normally it takes at least 40 minutes to properly dry out the room.

If your concern is how easily you can forget to turn the fan off then you can install a fan timer that automatically turns off the fan after a set amount of time.

Conclusion

In summary, you actually should install your bathroom exhaust fan in your shower, preferably right over it, where the hot moist air flows directly first. Make sure your electrical circuitry is GFCI protected, and that the fan is rated for shower use.

Remember that you must follow your local building codes for safe installation! Finally, use your newly installed fan responsibly, reducing any risk to yourself and your home!

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Joonas Pütsepp

I like it when I'm able to fix everything that needs fixing around the house. In order to do that, I have to do a lot of research. This site will cover everything I learn and maybe help others do the same.

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