Most exhaust fans work best when placed near the bathing area to maximize their effectiveness. In such a position, exhaust fans will remove the moisture and odors and add to the home’s safety and occupants by reducing fumes from cleaning agents that could potentially cause health-related issues.
However, can you install an exhaust fan with light directly above a shower and still eliminate moisture to the outside of the house?
You can place a fan directly over the bathtub or shower base only if it’s UL listed for installation over a tub or shower. If the bathroom has both a tub and shower or a shower and a whirlpool tub, the fan should go somewhere between the two fixtures. Units that include any heating function cannot be installed over a tub or shower.
Where to Position a Bathroom Exhaust Fan
Where you position a bathroom fan makes a significant difference in how effective it removes moisture. It also makes a difference in how the airflow affects people using the bathroom.
There best place to place a bathroom fan is in the ceiling, close to the shower. However, it shouldn’t be directly over the shower.
While it’s okay to install a shower-rated bath fan just directly above the shower, it’s best to install it slightly away from it if you want maximum comfort.
But several factors must be taken into consideration when deciding where to place a bathroom fan. Of course, some factors are more important than others.
The placement of the fan is crucial, but the most important is to ensure the bathroom fan is used regularly and for long enough periods.
Placing the Bath Fan Near the Shower Makes it More Effective
Although the bathroom fan will exhaust moist air out, it becomes more effective if you place it near the shower regardless of where you place it.
This is mainly because the steam will be easily exhausted from the house, drawing in fresh air from the gap under the door.
Compared to placing it above the shower, the advantage of this placement is that the shower corner will stay warmer.
This placement makes it suitable to use a light/fan combo to keep the bathroom as minimalist as possible.
However, you shouldn’t worry if you’re unable to place the fan exactly near the shower. As long as it is in the exact general location, you’re all good to go.
Placing the fan near the shower will also offer efficient ventilation, and it doesn’t compromise comfort.
Placing the Bathroom Fan Directly Above the Shower is Not a Good Idea
Although most people recommend placing the bath fan directly above the shower, it’s not considered the best option.
That’s mainly because it should make the fan more effective. After all, it’s closer to where the steam is generated.
But, in reality, there isn’t any measurable difference in the speed at which it exhausts moisture compared to placing the fan above the shower or near the shower.
Since a bathroom fan exhausts air out of the bathroom, the same amount of air is supposed to come back in.
This air is usually colder than the air in the bathroom, making the person showering feel cold.
This mostly happens, especially during the winter months when the temperature of the rest of the house is low. If you place the bath fan directly above the shower, the colder air that replaces the exhausted air will move right past you and create a cold draft.
The air that moves past you will be room temperature, but it will feel cold because the air in the shower is warmer. But, if you enjoy taking cold showers, this can be a great option.
When you have a bathroom fan drafting cold air out of the fan itself, then you might have a defective backdraft damper issue.
Therefore, if there’s no upside to placing the fan in the shower and a high chance of a cold draft, you should not install it in the shower. It’s recommended to place it several feet away from the shower – that is, between the door and the shower.
Several factors impact the intensity of the cold draft. They include:
- The room temperature
- Where the makeup air is coming from
- The bathroom fan capacity
If you’re not bothered about cold drafts, and you prefer installing the bath fan directly in the shower, there are several things you should keep in mind.
Where Should You Place the Fan in an Enclosed Shower?
There isn’t any risk of cold drafts in an enclosed shower because the air cannot flow directly on you. It’s supposed to come under the shower stall door or through small cracks.
This ends up slowing the air movement and won’t cause a noticeable draft. Hence, it’s not a good idea to place the fan inside the shower stall/cubicle.
This is similar to why a shower stall prevents a bath fan from causing a cold draft and preventing it from efficiently moving air.
Unless you have a shower enclosure with a large gap under the door (which is highly unlikely), there won’t be any sufficient makeup air available. This means that fresh air cannot replace the moist air that is being exhausted.
This will make the fan less effective, thereby negating any benefits one would get from placing the bath fan inside the enclosure.
However, if your shower enclosure has a large enough gap under the door (or another opening), then it’s okay to place the fan inside it.
The only benefit you’ll get from doing this is that you won’t have to leave the stall door open after taking a shower. But, of course, if the fan is outside the enclosure, you should always leave the door open.
Pro Tip: Some municipalities require a second bath fan if you plan to install one inside the shower enclosure.
Similar to a standard shower, the practical position is close to, but not directly in, the shower. That means you should place the bath fan one foot away from the shower enclosure door.
Always remember to leave the shower door open after having your shower to make it dry out faster.
Try as Much to Avoid Obstructions
There shouldn’t be any towel racks, drawers, or other furniture/appliances between the shower and the bathroom fan for the air to move correctly.
But if you have the fan placed somewhere not visible such as behind a large cabinet, the airflow will not be adequate. The good news is that there is a solution for that, which offers no visible dust-filled bath fan grille and excellent ventilation.
If you prefer hiding the fan, then you have the option of buying a fan/light combo. This can offer you an ideal solution for hiding your bath fan.
A Ceiling Mounted Fan is More Efficient
There are three different types of bathroom fans. However, ceiling-mounted fans are considered to be the most efficient ones. This is mainly because the steam from the shower moves up and naturally moves into the fan.
Even though installing a bath fan on a wall is not a bad idea, it’s important to note that this will make it less efficient. That’s because the warm moist air will be collected near the ceiling.
Since the wall-mounted fan exhausts air out of the bathroom, only some of it will be the moist air from the ceiling. So instead, most of the air will be drawn directly in front of the fan.
This is because there will likely be a gap between the fan and the ceiling, which will suck in some dry air. Therefore, it’s best to exhaust the steam as fast as possible to prevent it from condensing on cold surfaces.
This will decrease the time it takes for the bathroom to dry after you take a shower. This is also why the bathroom fan CFM needs to be correct for the size of the bathroom.
To find the correct figures, you can calculate the CFM, which will help you find the optimal airflow for your bathroom. A well-sized bath fan will keep the bathroom mold-free, and depending on the temperature of the bathroom, it can even keep the mirror from fogging up.
Check where the Fresh Air is Coming From
Even if you position the bath fan at the right spot, if there isn’t sufficient makeup air available, it won’t work. There must be a gap under the bathroom door or any other means for air to enter the bathroom.
If your bathroom door doesn’t have a gap, then consider trimming one. But before cutting it, ensure you test first to see whether it’s necessary. After that, install the fan and turn it up all the way.
Go ahead and open the bathroom door half an inch. If the airflow tries to close the door, then know that there is no sufficient makeup air available. And you either have to cut the underside of the door or install a vent in the door.
Some people even use weatherstripping on the bathroom door and eliminate the door gap to increase the soundproofing of the door. Although this can make the door considerably soundproof, note that it will also make the bathroom fan useless when you close the door.
If you soundproof the door, ensure there is an additional makeup air vent in the bathroom. You can strive to ensure it’s coming from another room and not directly from the outside. Therefore, this will help to prevent cold drafts.
Double-Check the Attic for Any Obstructions
Before selecting a location, check the attic to see if there is sufficient space where you’re planning to install the fan.
Installing too close to the soffit, there might not be enough room to move around and connect the duct to fasten the fan to the joists.
During installation, ensure you plan on how to run the duct and where to terminate it. You can choose to terminate it through the roof or the soffit.
Things You Need to Consider Before Placement
Here is everything you need to consider before installing a bathroom fan.
The size of the duct plays a significant role in the efficient functioning of a fan. An undersized duct will make the fan louder and reduce its capacity to move air.
The best option is to use almost the same size duct on the bath fan housing connector. If the duct run is longer than 20 ft., then consider going up one size.
The most recommended is either rigid metal or PVC. However, if you have a short duct run, then you can use a flex duct.
You need to find the shortest and straight path from the fan to the termination point. The fewer the turns and the shorter the duct, the more efficient the entire system will be.
It’s crucial to insulate the duct to prevent water from dripping back into the bathroom and causing brown stains around the bath fan.
You should ensure that you place insulation above the fan housing. Check whether your fan can be covered without the need for clearance or box for clearance.
The bathroom fan capacity is calculated according to the volume of the bathroom. Check out this bathroom fan calculator to find the correct airflow.
The fan needs to have sufficient capacity so that it can dry the bathroom as fast as possible.
How to Size a Bathroom Exhaust Fan
Bathroom fans are sized according to the amount of air that they can move every minute. The Cubic Feet per Minute measures refer to air volume that the fan moves in every 60 seconds. Fans with high CFM scores are ideal for large bathrooms.
Getting the right size of a fan in terms of CFM ensures that your bathroom is properly ventilated. If you use a small fan in a large bathroom, the air quality will remain poor even if you let the fan run nonstop. Similarly, using large fans in small bathrooms amounts to wastage of electric power because such fans consume a lot of wattages.
Here is a simple procedure that you can use to size a bathroom exhaust fan.
- Calculate the total volume of the bathroom. This process entails multiplying the length and width, and height of your bathroom. For practical purposes, assume that your bathroom measures 10 feet by 10 feet by 10 feet. Therefore, the total volume would be 1000 square feet.
- Multiply the volume of your room with 8. Figure 8 is the standard number of air changes per hour. This gives you 8,000.
- Divide your answer with 60 to determine the correct CFM needed for your bathroom. in your case, the final solution would be about 133 CFM.
- Adjust the final CFM based on the conditions of the bathroom. If the bathroom is poorly insulated, add about 50 units to get the final CFM required to ventilate the space properly.
Ensure to Vent the Outdoors
It’s highly recommended for the bathroom fan to always vent outside of the building envelope. It’s even considered more important to have a bathroom fan instead of venting it to the attic.
That’s because if there’s no bathroom fan, the moisture damage from not having a bath fan can be visible in the form of growing mold in the bathroom.
But, if the moist air is exhausted into the attic or any other hidden space, then the mold and mildew can grow for years without anyone noticing. As a result, this can end up costing you tens of thousands of dollars to clean it up.
Positioning a bathroom exhaust fan correctly is crucial to consider if you want it to be effective enough.
There are many ways to do it, but choosing the most efficient and effective position is always the best option to consider,
Doing that will help you have a bath fan that will serve you better and one that will be there for a very long time.
I hope this post has been of help to you. If you have any questions or feedback regarding our post, feel free to reach out to us through email, and we’ll be happy to help!