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Where Should a Bathroom Fan Be Placed

We all know the immense benefits of bathroom exhaust fans. Placed anywhere in the bathroom, these fans will be helpful. However, there is an optimal placement for these appliances.

The placement of the bathroom fan makes a big difference in how effectively it removes moisture, as well as how the airflow affects people using the bathroom. As such, there are a number of things that must be taken into account when deciding where to place a bathroom fan.


A bathroom fan should ideally be placed in the ceiling approximately 1 foot from the shower and between the shower and the door. While installing a shower-rated bath fan directly above the shower is permitted, this installation creates drafts and heat loss in the shower.

Placing Fan Close to Shower Makes It More Effective

While the bathroom fan will exhaust moist air out of the bathroom no matter where it is placed, it will be more effective if placed close to the shower (about one foot away).

Optimal placement also includes being installed between the shower and the door, as shown in the illustration.

optimal bathroom fan placement
Optimal bathroom fan placement

Don’t worry if you are not able to place the fan exactly as in the picture. As long as it is in the same general location, you will be fine.

The bathroom fan is supposed to remove humid air from the bathroom before it can cause damage. As you can imagine, this means that it will work best if it is situated close to the source of the humid air, i.e., the shower.

By placing the fan as shown in the picture (or in a similar location), the steam will be easily caught by the fan and exhausted out of the house.

Fresh air will be drawn in from the house through the door (or gaps around the door) and any open or imperfectly-sealed windows to replace this exhausted air. This air will get steamy and removed, and so the cycle goes.

As a bonus, having the fan near the shower can also serve as task lighting if you get a fan that has a light feature.

It can even serve as your main lighting fixture in the bathroom, allowing you to keep the bathroom looking as minimalist as possible. This is great in smaller bathrooms.

But if placing the fan close to the source of the steam makes it more effective, then surely placing it directly above the shower stall will be even better. Moreover, if it’s going to double as task lighting, then once again, placing it directly above the shower is better.

Theoretically, this is true from a purely exhaust efficiency and lighting point of view. However, reality differs slightly as you will see in the following sections.

Near or Above Doesn’t Make a Difference

While many people recommend placing the bath fan directly in the shower, it’s not the best solution, practically speaking.

As mentioned above, theoretically, it should make the fan more effective since it is closer to where the steam is generated.

However, in real life, there is no measurable difference in the speed at which the moisture is exhausted when comparing placing the fan above the shower to simply installing it close to the shower.

This is really good news for us shower users because having a fan directly above the stall is going to make our experience of a nice warm shower a little less warm and a little less enjoyable.

Fan Directly Above Shower Makes It Chilly

Warm Air Is Pulled Away

Bathroom fans do not extract moisture from the air like a dehumidifier. They exhaust the actual air.

This means the moisture-containing air is completely removed from the room in order to achieve the appliance’s functional goal.

But it also means that the air heated by your shower is removed and replaced with colder air from outside or other parts of the house.

If the fan was essentially in the shower with you, you would feel the loss of heat more strongly because it is the warm air surrounding you that is removed.

When the fan is simply near the shower, your personal bubble of warm air is left intact.

You can think of it like this: the steamy air removed by the nearby fan is the air that has already been displaced from around you by new warm air.

Cold Air Blows Over You

There is another reason why this placement can mean a colder shower no matter how hot you make the water. This reason is the wind chill effect.

Wind chill occurs when the heat sitting against your skin is moved away by flowing air.

Heat from your body will move down the newly created temperature gradient to the air surrounding you, cooling you down (even if you don’t want it to!).

As the air keeps flowing over you, your skin keeps releasing heat.

The addition of water makes this effect more intense because of evaporative cooling, which you will be familiar with as it is the same principle behind why we sweat when we are hot.

The intensity of the cold draft depends on the following factors:

  • Room temperature
  • Bathroom fan capacity
  • Where the make-up air is coming from

If the fan was directly above you, it would mean that the air being pulled into the fan is constantly flowing over you, cooling you down. If the fan is to the side, you feel the airflow less strongly.

So, there is no real benefit to placing the fan in the shower and it will actually make showering cold and less pleasant.

If you ever feel cold air actually coming out of your bathroom fan, there is a problem—most likely a missing or defective backdraft damper—that needs to be addressed.

Fans Placed in Showers Are Exposed to Water

If you are not worried about cold drafts and you would like to install the exhaust fan directly above the shower, there are a couple of things that should be kept in mind.

This is because you are installing an electric device in a space where it can be splashed with water over and over again.

Fans above showers must be connected to a ground fault circuit interrupter (GFCI) and the fan must be shower rated.

Fan Placement in an Enclosed Shower

What about showers where the door and walls go all the way up to the ceiling? These showers are essentially closed off from the rest of the bathroom until the door is opened.

This means that a fan placed outside of the shower stall would not have very much to do until you were finished.

It also means that a fan inside the shower stall would be creating a bit of a vacuum, exhausting air and then struggling to replace it with fresh air from outside the shower/bathroom.

For clarification, enclosed showers are not airtight. There are small gaps and cracks through which air can move. Otherwise, you would pass out from carbon dioxide inhalation whenever you spent too long in the shower!

This would be one of the more extreme ways to learn about water conservation and not finishing the hot water before your sister has a chance to shower, but bathroom designers and shower manufacturers aren’t that invested in your personal life.

So, the small gaps and cracks in the shower installation would allow some steam to escape and be sucked up by an external exhaust fan, and it would allow some air to be pulled into the shower by an internal fan.

Fan in enclosed showers and Fan outside of enclosed showers

Fans In Enclosed Showers

If you were to install the fan in an enclosed shower stall, then you would not suffer the same cooling effects as in non-enclosed showers because the air has to infiltrate smaller spaces and won’t flow over you as quickly.

This seems like a good thing, but it actually indicates an inefficiency in airflow.

The exhausted air cannot be replaced, so the rate of exhaustion slows down and the fan cannot function as it is supposed to.

In essence, running the fan while you shower is pointless. The airflow will only provide efficient ventilation when the shower door is opened.

Furthermore, some municipalities require a second bath fan to be placed in the general bathroom area if your first is placed inside the shower enclosure.

It’s not all negatives, though. If the airtightness of your enclosed shower was limited enough not to impede relatively effective inflow of air, then you could leave the shower door closed after you are finished.

This contains the steam and allows it to be exhausted before it can move into other parts of the bathroom and cause damage or irritation (like foggy bathroom mirrors and counters covered in condensation).

My only caution here would be that the walls and ceilings in the shower would still be exposed and to a pretty concentrated level of steamy air.

Fans Outside of Enclosed Showers

While there are benefits to putting your fan in the shower enclosure, it turns out that in these cases, the best fan placement is still outside but near to the stall.

While you shower, the externally-located fan can still effectively function by removing any steam that escapes through the cracks and gaps of the enclosure.

Then, when you are finished showering and you open the door, the fan can get to work removing the bulk of the steam generated.

For the same reasons as before, you will also not have the problems of heat loss and cooling with this fan placement.

You will, however, have to leave the shower door open when you are done to allow the steam to move into the area around the fan.

Depending on the size of your bathroom and the swing direction of your shower door, this can be rather inconvenient.

Avoid obstructions

In order for the air to move efficiently there should not be any towel racks, drawers ,or other furniture/appliances between the shower/bath and the bathroom fan.

These obstructions create airflow turbulence and increase the amount of time the steam spends in your bathroom. In other words, there is more time to cause damage.

Now, I understand bathroom fans can be really ugly, particularly if they are slightly neglected and there is a buildup of dust, or if they are older and the plastic grille has become discolored.

However, as tempted as you are to hide it behind a cabinet, doing so will severely impact efficiency.

Fortunately, you don’t just have to live with an ugly bathroom fan. There are options like the fan/light combo (amazon link) pictured below that look just like a regular light.

Hunter 90054z Saturn Decorative Bathroom Ventilation Exhaust Fan and Light, 80 CFM, Matte Black

Ceiling Mounted Fan is More Efficient

There are 3 different types of bathroom fans as categorized by installation location, but ceiling-mounted fans are the most efficient as steam moves up and will naturally move into these fans.

While it’s perfectly fine to install a bathroom fan on a wall, it will be less efficient.

The warm moist air will collect near the ceiling because hot air naturally rises. A wall-mounted fan will have to draw this air back down from the ceiling in order to exhaust it.

bathroom fan on a wall will be less efficient

Some drier air pulled in from below the “steam line” will also be exhausted, which has an impact on efficiency because a fan can only exhaust X amount of air per minute. Any non-steamy air removed in a given minute means that less steamy air is removed.

Ultimately, this means that steam is going to take longer to leave the bathroom and, as mentioned, the longer it lingers, the more damage it can do.

If you are going to install a wall-mounted bathroom fan, make sure to install it close to the ceiling.

The fact that bathroom fans are only able to exhaust a certain volume of air at a time is also why it is important that the bathroom fan CFM (cubic feet of air per minute) is correct for the size of the bathroom.

You can use our CFM calculator to find out what is optimal airflow for your bathroom as well as our guide on the 6 Easy Steps To Choosing The Right Bathroom Exhaust Fan.

Consider Where the Fresh Air Is Coming From

Even if the bath fan is placed in the exact right spot, if there is not sufficient makeup air available, it will not work as well as it should.

There must be a gap under the bathroom door or another means for air to enter the bathroom. If your bathroom door does not have a gap, don’t worry; it is quite easy to trim it down.

Trimmed down door and door with vent

Before you start cutting the door, test if it is even necessary. Install the fan and turn it up to the highest setting, then open the bathroom door half an inch.

If the airflow tries to close the door, there isn’t sufficient make-up air available and you either have to cut the underside of the door or install a vent in the door.

I have seen people using weatherstripping on the bathroom door and eliminating the door gap to increase the soundproof capability of the door.

While it will make the door considerably more soundproof, it will also make the bathroom fan almost completely useless when the door is closed.

If the door is soundproofed, there must be an additional makeup air vent in the bathroom. Ideally, it should be coming from another room, not directly from the outside (this will prevent cold drafts).

Double Check the Attic for Any Obstructions

Before you decide on a location for your bathroom fan, take a look in the attic to see if there is sufficient space where you are planning to install it.

If you install it too close to the side of the house, there might not be enough room to move around and connect the duct to fasten the fan to the joists.

While you are up there, make a plan on how to run the duct and where to terminate it.

It is possible to vent the fan through either the roof or the soffit. I always recommend people who do not have previous roofing experience to go through the soffit. This way there is no risk of future water damage from the leaking roof vent hood.

What Else Besides Placement Is Important

While the location of the fan is important there are other factors that should be taken into account when installing a bathroom fan. Look at this as a sort of checklist to make sure you have addressed all the relevant points.

Permits

Make sure you don’t forget to pull a permit if one is necessary in your state/area. Or if you hire someone to install the fan make sure they do it. In most cases, contractors will pull permits.

Duct Size

The size of the duct is crucial for the fan to work efficiently. An undersized duct will make the fan much louder and reduce its capacity to move air.

The general recommendation is to use at least the same size duct that is on the bathroom fan housing connector. If the duct run is longer than 20 ft, consider going up one size.

Duct Type

Rigid metal or PVC duct is preferable. If the duct run is short, a flex duct can be used.

Duct Route

Find the shortest and straightest path from the fan to the termination point. The fewer turns and the shorter the duct is the more efficient the entire system will be.

Duct Insulation

Ducts only have to be insulated when passing through an unconditioned space but there are many benefits to insulating bathroom fan ducts in general. It reduces noise, prevents dripping, and more.

Also, don’t forget to place insulation above the fan housing. Find out if your fan can be covered without clearance or if it needs a box for clearance.

Fan Capacity

The bathroom fan capacity is calculated according to the volume of the bathroom. I have created a bathroom fan CFM calculator you can use to find out the correct airflow.

BATHROOM FAN CFM GUIDE

It is important that the fan has sufficient capacity in order for it to dry the bathroom in a timely manner.

Must Vent to the Outdoors

The bathroom fan must always vent outside of the building envelope. I can not stress enough how important this is.

In fact, having no bathroom fan could be better than venting it to the attic.

If there is no bathroom fan, the moisture damage from not having a fan will be visible in the form of mold in the bathroom.

However, if the moist air is exhausted Into the attic or any other hidden space, the mold and mildew can grow for years without anyone noticing. This can end up costing tens of thousands to clean up.

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