5 Proper Bathroom Exhaust Fan Venting Options (Up To Code!)

A bathroom exhaust fan vent is a vent in your bathroom that carries away the old air from your bathroom to the outside.  It removes humidity, odors, and other air pollutants from your house thereby improving the quality of the air in your home.  It also minimizes the harmful effects of moisture damage to your home.

Five of the best options for a bathroom exhaust fan vent are installing a ceiling-to-wall vent, a roof vent, venting through the wall, a soffit vent, and a low-profile vent.  A bathroom exhaust fan installation is a project that can be done by a professional or as an advanced DIY project.

You may not usually give much thought to your bathroom fan. It is easy to forget to use it.  But you cannot afford to ignore your bathroom exhaust fan.

I’m going to tell you why a bathroom exhaust fan is important. Then I’ll give you some options for installation and how to install it.  Read on for some important tips.

Why is a Bathroom Exhaust Fan Important 

A bathroom exhaust fan vent protects your home by removing moisture and humidity from the air, improves your indoor air quality, and usually is required by building code regulations. The bathroom exhaust fan vent provides much-needed ventilation to your bathroom.

Exhaust Fan Diagram

Many new buildings and bathroom remodeling projects are required to install a bathroom exhaust fan as part of the construction. But even when not required, it is a good idea for your home.

Bathroom exhaust fans will vent out odors and other pollutants that gather in your bathroom.  This will make using your bathroom a more pleasant experience.

The primary reason that bathroom exhaust fans are important, however, is that they also take moisture and humidity out of your bathroom. If left unchecked the water in the air can settle down onto and in your walls and soak into your floors. This will eventually result in water damage to your home, rusting and corroding metals, and rotting the wood.

The presence of moisture in your bathroom will also encourage the growth of mold and bacteria.  Over time, this can make your bathroom unhealthy and unsanitary.

An exhaust fan is a small part of your bathroom. However, it plays an essential role in keeping you safe and your house free from harm.

Five Options For a Bathroom Exhaust Fan Vent 

When installing a bathroom exhaust fan vent, there are five options for how you can vent. They are ceiling-to-wall, a roof vent, through-the-wall, soffit ventilation, and low-profile ventilation. Let’s go over these types of ventilations and the advantages and disadvantages that each one brings to the table.

Ceiling To Wall

A ceiling-to-wall exhaust fan vent is the most common setup in homes today.  It is installed in the ceiling of a bathroom and runs through ductwork to the outside wall. 

One of the downsides to a ceiling-to-wall exhaust fan vent setup is that it makes for inefficient airflow.  In order to run from the ceiling to the wall, at least one ninety-degree turn will be needed, if not more.  Every turn or bend in the ducting further reduces the airflow.

Rain entering the ducts is also a potential issue, though it is not as big of a problem as it would be with roof ventilation.  There is also the potential for animal intrusion. The vent opening makes a perfect spot for bird nests which will obstruct your vents.  

One solution is installing a hood or vent cover with a ‘flapper’.  This will keep the local wildlife and rain out of the ducts.

Roof Vent

After venting through the wall, roof venting is the next most common setup.  A roof vent setup has the same setup as a ceiling-to-wall vent but goes straight to the roof.

The advantage that this has over the ceiling-to-wall setup is that the distance to travel for air is usually shorter, and it usually takes a direct path.  This means that ventilation is much more effective than a ceiling-to-wall setup because of better airflow.

Roof Vent

The downside to this setup is that, like a wall vent, it is vulnerable to bird nests and other wildlife.  It is even more vulnerable to rain than a ceiling-to-wall setup.

Again, a vent cover or a hood is usually installed to mitigate this problem.  Because it is on the roof, the cover or hood must be more resilient than a wall vent.  The vents are usually made out of stainless steel or material that can stand up to the elements.

Through the Wall

An alternative to ceiling-mounted vents is vertical vents, also known as wall vents. In a through-the-wall setup, the vent is placed on the wall of your bathroom. 

Through-the-wall vents consist of an exterior cover and a very short amount of ducting – enough to get through your wall.  This makes for a short path for airflow, making the airflow more efficient. 

Through the Wall exhaust fan

The advantage of through-the-wall vents is that it allows for ventilation when ceiling mounts are impractical.  It also makes for an easier installation, as the ductwork only has the width of your wall to travel.

The downside to this setup is that a through-the-wall vent may not provide your bathroom even coverage.  The further the area is from the vent, the harder it is for that air to be purified.  The warm air that rises above the vent level has more time to affect the ceilings of your bathroom as well.


Soffit venting is another type of ceiling-mounted venting.  This is a passive setup, as there may be no fan to assist with airflow.  Soffit venting opens up a path for your air to be vented into the attic.

Soffit ventilation is actually used for attic or roof ventilation. It allows for airflow in your attic, which can potentially extend your roof’s life and prevent mold growth.


Soffit exhaust vents aren’t common in bathroom venting setups.  Part of the reason is that some local building codes do not allow this type of venting. This is because this type of setup is not necessarily ideal for homeowners.

The primary issue with this type of venting is that ventilation into your attic will spread moisture into this space.  Depending on the ventilation of your attic, this may not be a significant issue, but it does introduce the possibility of mildew and mold growth.

Low Profile

A low-profile exhaust fan vent can be installed in either the ceiling of a bathroom or in the wall.  These vents are thinner than through-the-wall options and can be routed out through the wall or even up through the roof. The way that the vent ends (either wall or roof) will still have to deal with rain or wildlife from the outside.

Low-profile vents are, as the name suggests, a less bulky option. With through-the-wall exhaust fan vents, the air is exhausted out behind the fan.  Low-profile vents exhaust the air out of the side of the fan.

Low Profile

The flexibility in routing is both an advantage and disadvantage.  The more direct the ducting, the better the airflow.  However, direct routing is not always possible, and low-profile fans give homeowners the ability to route their ventilation when routing ducting directly out of the wall or through the roof is not feasible. 

How to Install a Bathroom Vent 

Depending on your skill level, you can install a bathroom vent yourself as a DIY project. The various types of ventilation are usually found in kits.  If you have to purchase it separately, make sure that you have the fan that you will be using, the ductwork you need to reach either the wall or ceiling, and the cover or hood for the exit vent.  

Roof Vent Installation

If you decide that your venting will go through your roof, you will have to identify exactly where on your roof.  You will have to make a hole in your roof in order to finish the installation, so you need to get this right the first time.

The vent should have a short route that is as free of bends as possible.  In addition, you will want to make sure that the roof vent is two feet from other vents, roof valleys, or other openings like chimneys.

The next step is making the hole in your roof.  A good idea is to hammer a nail into the ceiling of your attic so that you can find the spot on your roof. From here, remove the top layer of shingles, fit the vent, then cut your venthole through the bottom shingle layer with a reciprocating saw.

When installing your vent, make sure that you pay attention to calking and sealing the vent.  Mistakes in this part will cause your roof to leak.  The best bet is to have a professional help you with this part of your installation.

Ceiling-to-Wall Vent Installation 

After deciding what size fan you will need for your bathroom, you will need to know where you will install it.  In most bathrooms, the most optimal place is over your toilet.  However, if there is a separate room or area for your shower or bath, consider installing two fans.

In order to make sure you’re working in the right place, drive a nail through the ceiling in the exact center of where your fan will go. 

The next step is to go up into the attic, mark off where you are placing your fan, and start cutting. If you cannot do this due to accessibility issues, you can cut into the ceiling from below, but you may want to use a stud finder to find the joist.  If you cannot see the other side, you may also want to turn off the power for your safety.

The next steps are to cut the vent in the wall. For more details, check the wall vent installation section, as the procedure is largely the same.

Through the Wall Vent Installation

First, you will need to cut a hole in the exterior wall for your exhaust.  The type of tool you use depends on the type of wall you have – a brick exterior may require a diamond hole saw. 

If you are going through the wall, cut through halfway, then finish the cut on the inside. Make sure that the power is off before you begin cutting to prevent accidental electrocution.

When the vent hole is cut, install the exterior cover. It is also a good idea to caulk the edges around your vent to ensure you get a complete seal.  This is to prevent bugs and moisture from entering your ventilation system.

When you are done, the next step is to make sure your ductwork is in place and then install and wire the interior fan. This is done in the same way as a roof fan, except you will be working vertically. 

Soffit Vent Installation

Firstly, make sure that venting your bathroom through your soffit is allowed per your local building code.  If it is, you can proceed.

If you are using ductwork, make sure that it is straight, as bends and turns will cause condensation to build up.  Next, make sure that you are cutting your soffit hole in the right place.  Some manufacturers include templates that can assist you with drawing out where your vent will go.  

Cut the hole, and then attach the soffit vent.  If your vent has a cover, you will screw this in place as well. You will then connect your soffit to any ductwork that you are using.

You can also use the soffit to vent from a fan to your outside, though this is not recommended with building codes either.  The process for this is similar to the installations above, except that you will be installing the soffit into the eves of the house and connecting it via ductwork to the fan.

Low Profile Vent Installation 

A low-profile ventilation installation is done similarly to the wall or ceiling installation, except that routing ductwork becomes more important.  As a key principle, remember that the more bends in the ductwork, the less effective the ductwork will be.

Select the location for your installation (again, it’s best above the toilet). Cut into the ceiling carefully after turning off the power.  You will be installing the vent into the joist.

Carefully mount the vent fan and screw it into place.  The next step will be wiring the fan.  

Run the wires that you need to where they will need to go and attach them to the wires that will power your fan. Some installers will attach their fan to the light switch so that it only runs when someone is in the bathroom.  Finally, finish up and close up your vent, then restore power to your house so that you can check your work.

Should You DIY It or Hire Someone? 

Installing a bathroom exhaust fan is an intermediate to advanced DIY project that involves electricity and potentially making holes in your roof – if you do not have this type of experience, you should hire a professional.  The cost of installation ranges from $240 to $548.

You can address the parts of the installation that you are experienced with yourself to save you cost.  However, cutting into your roof runs the risk of weakening it and causing leaks in the future. And working with electricity carries the hazard of electrocution.

Another benefit of getting professionals to do the work is that you can ensure that your installation is up to code. They can also advise you on which type of installation is best for your home.

If you do decide to do it yourself, you will only be paying for the cost of materials (and tools if you don’t have them).  Ducts will run you around $25 for the length you need, and the external vents will be between $50 to $350 depending on where you are venting to. Finally, the fan itself will cost you between $15 and $420, depending on the type of fan and included features (some come with LED lights and Bluetooth speakers).


As a homeowner, you have several options for installing your venting system.  Each comes with its own advantages or disadvantages, but it is worth the installation to avoid water damage to your home and hazards to your health.  If you do get a new fan, look for one that is HVI-certified.  

This means that the fan has a high performance, and is a good option for your home.  And if you have any questions, check with your local professional contractor before you install an exhaust fan.

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