So, your newly built or renovated bathroom is almost complete, and all that’s left is the exhaust fan. Exhaust fans are designed and installed to pull steamy air out of your bathroom. It would make sense to remove it as close to the source as possible, i.e., from your shower stall.
However, bathroom fans are electrical devices, and showers are wet environments. While there is a way to do it, extreme care must be taken whenever working with electricity in a damp environment. There are also other factors to consider.
A bathroom fan can be installed in a shower. However, it must be connected through a Ground Fault Circuit Interrupter, and the fan must be shower-rated. Fans in enclosed showers serve only the shower; another fan is required for the rest of the bathroom.
Conditions for Bathroom Fans in Showers
Bathroom exhaust fans can be installed in shower cubicles as long as certain requirements are met.
The first requirement is that the circuitry must be protected by a ground fault circuit interrupter (GFCI).
The second requirement is that the bathroom fan itself must be shower-rated.
This is an “and” requirement, not an “or” requirement. If your home is older and the electrics are not GFCI-protected, a shower-rated fan is not sufficient protection.
Let’s look at these two requirements a little more in-depth.
What Is Ground Fault Circuit Interrupter Protection?
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 to which it is connected, the GFCI de-energizes it in milliseconds.
This is crucially lifesaving in certain instances, such as the contact between electricity and water, which could cause fatal electrocution in a shower with an exhaust fan in it.
Sometimes, depending on the manufacturer, the bathroom fan itself needs to be GFCI protected in addition to the house circuitry.
But who says that the electrics need to be GFCI protected (apart from logic)?
The US National Electrical Code (NEC) says so.
It 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.
What Is Meant by an Exhaust Fan Being Shower-Rated?
You cannot install just any exhaust fan in your bathroom. The GFCI will protect you if water gets on the electrics, but there is no point in having GFCI protection if you don’t take steps to prevent the meeting of water and electricity.
Here is where the fan rating comes in. Bathroom fans that are used in showers have to be rated for use in the shower.
What this means is that the manufacturer has deemed (rated) it appropriate for use in a bathroom setting according to specific standards.
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 (not just humidity, but splashes too) and is safer to use in such environments compared to a regular exhaust fan.
Always check the manufacturer’s specifications for an indication of the fan being shower-rated to avoid possible accidents after installation.
The GFCI protection is required in addition to the fan’s shower rating because devices are not fail-proof.
A worn out piece or a single crack in the build can open up a path for water to the electrics. If this happens, you need to ensure that you don’t suffer for this failure.
What’s The Best Position to Install a Bathroom Fan?
If both of the above requirements are met, then it is considered safe enough to install the bathroom fan in the shower.
However, the best location for a bathroom fan is close to the shower (approximately one foot from the shower) but not directly inside the cubicle.
It should also be on the ceiling and between the shower and the door, although this depends on where the two are in relation to one another.
The reasons for this placement relate to how bathroom exhaust fans work, where steam is generated, and how steam behaves. Let’s break it down.
- Near to the shower – as the source of most of the steam in a bathroom, you want the fan to be close to the shower to catch as much steam as possible before it has time to move throughout the room, fogging up mirrors and giving your wooden cabinets an unwanted steam-clean.
- Not in the shower – bathroom exhaust fans pull air from the room and replace it with air from outside (the room/house). If the fan is in the shower, the resultant “breeze” will be blowing over you while you are trying to enjoy your warm shower!
- On the ceiling – steam naturally rises. So, just like placing the fan near the source helps to ensure efficient steam removal, placing the fan on the ceiling where the steam gathers will help the fan to operate in the most efficient way possible.
- Between the shower and the door – as the fan pulls replacement air from outside the bathroom, if the layout as door-shower-fan, air replacement wouldn’t be as efficient. If replacement air doesn’t eliminate the vacuum created by steam removal, negative pressure further impairs steam removal.
What About Bathtubs?
If you have a bathroom that has no shower at all (including bath/shower combos) and only a bath, the positioning of the bathroom fan will remain the same, except that you can position it directly over the tub.
This is safer than with a shower because the bath and its faucets are lower.
Additionally, you are less likely to bothered by the breeze because you are lower and the bath is not enclosed by walls, which limit the path of the airflow. In other words, any draft created is blowing above your head.
If you have a bath/shower combo, then you can apply the same bathroom fan placement conditions as shower cubicles.
For bathrooms with both a bathtub and a shower cubicle, you will want to keep the placement the same; a foot or so from the tub and the shower, on the ceiling and between the tub and shower and the door. If you have to place it over the bathtub, that’s fine.
If you have an enclosed shower in which the walls go all the way up to the ceiling, then putting the bathroom exhaust fan in the shower means that you also have to install one in main area of the bathroom.
Furthermore, the fan’s efficiency is impaired. The air being removed will not be able to be properly replaced as this air has to find its way through cracks and crevices in the enclosure.
As the replacement air supply is impaired, removing the steamy air takes more work because it is pulling against a negative pressure gradient already.
Ducting Can Influence Fan Positioning
The ducts linking the fan to the outside (bathroom fans have to terminate outside) have to be as short as possible and as straight as possible. This is to ensure that the air passing through them does not lose its velocity before it can be expelled.
If it did, the moisture would condense in the ducts and drip back through the fan, which can cause all manner of issues.
While it is unlikely that installing the fan in the ideal location described above would be much different from installing it a foot to one side in order to be in the shower stall, it is still something you have to consider.
What If I Have a Window In My Bathroom?
Do you even need a bathroom fan?
If you have an operable window, then technically, you don’t need to install a bathroom fan. Of course, this relies on the assumption that you will open your window every time you take a shower or bath.
Cold weather, wet weather, safety, and privacy are all going to stop you from properly utilizing natural ventilation. Even in summer, you won’t want to leave your windows open to let all the cooled AC air out.
With this in mind, you should probably install a bathroom exhaust fan in your bathroom even if there are windows.
How Long Should the Bathroom Fan Be Left On After a Shower?
If you are going to be installing an exhaust fan in your bathroom, then you should know about one of the most common mistakes that users make.
So many people turn their exhaust fans off when they come out of the shower or leave the bathroom. This is not the best practice because steam is generated faster than it is removed.
You might think that your fan needs to be in the shower to be more effective when, in reality, you’re just turning it off too soon.
When you get out of the shower and turn the fan off, the steamy air in the ducts stops moving, cools, and condenses. This can rust ducts and drip from fans. In addition, all the steam still in the bathroom as well as the invisible moisture in the air will stay there, causing moisture damage in the bathroom.
The fan should be left to run for at least 20 minutes after you are finished showering. Depending on your fan, 40 minutes or an hour might be more effective.
On the other hand, leaving a bathroom fan to run for too long comes with its own problems and risks. 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 noted by the US Consumer Product Safety Commission (CPSC).
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.
You can install a bathroom fan in the shower but the electrics must have GCFI protection and the fan must be shower-rated. Additionally, if your shower cubicle is enclosed, you need to install another fan in the main bathroom area (unless you have and use sufficient natural ventilation).
While you can do it, a better position would be a foot from the shower cubicle, on the ceiling, and between the shower and the door.
Wherever you decide to install the bathroom fan, 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!