Your bathroom paint will last longer, the air will be better quality, and mold will not grow when you have an exhaust fan. The fan also removes the bath humidity and slows fixture rust. That is why a bathroom fan is the number one feature most prospective homeowners look for in a house. Installation of the fan is an inexpensive bathroom upgrade packed with lots of benefits. It can be a worthy DIY home improvement project. It will not be the easiest project, but it’s worth every sweat. Today’s best bathroom exhaust fans will help you escape the nasty health implications of having mold and mildew in your home. Expelling the moisture will improve your bathroom experience. Here are the steps to bathroom exhaust fan installation.
What You Will Need
Tools
- Oscillating saw
- voltage tester
- Drill and bits
- Utility knife
- Putty knife
- Tape measure
- Safety glasses
- Ladder
- Exterior grade silicone caulk
- Work gloves
- Work light
- Screws and a screwdriver set
Materials
- HVAC tape
- Wire connectors
- Nails
- Duct clamps
- Flexible insulated duct
- Pencil
- Stud finder
- Roof cap
- Exhaust fan
Sizing Your Bathroom Fan
Domestic exhaust fans usually come in two sizes, 6-inch and 4-inch. The size refers to the revolving part that sucks all the moisture out. But you have to consider other measurements if you want a maximum-functioning fan for your bathroom.
When sizing a fan, the rule of thumb is that you need at least 1cubic foot per minute (CFM) per square foot. So you will have to determine the footage of your bathroom. You should multiply the length by the width. For example, if your bathroom width is 6 feet and the length is 8 feet, your footage will be 48. So you should have a 48 CFM fan, but you can always go higher to ensure efficiency.
But most people always buy 100 CFM for a big bathroom and 50 CFM for a small bathroom. Sizing is essential when it’s a fresh installation. But if you are replacing an old fan, use the size of the old fan, so you don’t have to resize the hole in the ceiling. You will also find some recommendations on the fan package by the manufacturers. The primary consideration is your bathroom size.
After you have the right size, the next consideration is whether you need a quitter fan or not. The quitter fan is more expensive. The most common complaint about bathroom fans is that they can be too noisy. So you have to decide if the minimal noise is worth the extra cash. You should also consider getting a fan with a built-in moisture sensor if you have always had a mold problem. Even when it’s a replacement fan, you can still upgrade to a better version. You will find so many products in the market that are the same size as your old fan but have more advanced features.
Establish the Power Source

The bathroom fan will need an electrical circuit. You may be able to share the bathroom lighting circuit with the fan, depending on the local electrical code [1]. If the code allows you to share the circuit, you can go ahead with the installation. But if it requires a dedicated circuit for the fan, you will have to run a separate line from the service panel to your bathroom ceiling. If you can’t establish a new circuit by yourself, call an electrician to complete the task. You should check with your municipality to see whether you need a permit for this work.
Establish the Vent Point
The bathroom fan will have to exit outdoors for proper ventilation. You will have to run a duct to either the sidewall or the roof. If possible, run the duct or vent through the sidewall because when it goes through the roof, it will increase the risk of roof leaks. However, it may be hard to run the duct through the sidewall because the route needs to be pre-existing. If the venting was not installed when the house was built, creating a vent route today would be challenging. If you are going to use roof vent, ensure the vent point is tightly sealed.
A Step-By-Step Guide to Bathroom Exhaust Fan Installation
Step 1: Remove The Old Fan
When you need to install or remove electrical units like exhaust fans, you have to turn the power off. Turn it off at the circuit breaker and use the tester to confirm it’s off. You can rely on the working lights to illuminate the working area. Once the power is off, you can start the removal process.
Pull the cover down and remove it. Then pry out or unscrew the old motor using a screwdriver. Once the motor screws are gone, disconnect the system from the wiring. Wear your safety goggles at this stage to avoid debris in the eyes.
You then need to remove the housing. Unscrew the housing from the joist if it’s secured by screws. It’s better to access the fan through the attic because it makes removing the nails or screws easy. But if it’s not accessible from the attic, you will have to cut the brackets from the bathroom, but be careful not to cut any electrical wires.
Lastly, you will have to disconnect the electrical wiring. Slide the wires out carefully and disconnect the wire connectors. Once you disconnect all the electrical, you can pull the house wire and remove the exhaust duct from the bathroom fan. After everything is done, you should remove the fan housing from the ceiling.
Step 2: Measure and Cut A Larger Hole If Necessary
To determine whether you need a bigger hole, hold the new fan housing to the ceiling to see if it fits. If it doesn’t fit in the old fan hole, trace the perimeters of the new fan housing and cut the hole adjustments. Cut along the traced lines with your saw to create a bigger opening with the appropriate size that fits your new fan.
If you are working from the attic, it’s easier to maneuver around electrical wires while cutting. But if you are working from the bathroom, be careful not to hit plumbing or other cables on the other side of the drywall. If you are installing the fan for the first time, the attic will be the best place to work. Sometimes you will find the hole is too big for the new fan. When this happens, patch the ceiling wall to make it the correct size.
Step 3: Install The New Fan Housing.
Place the new fan housing inside the freshly cut hole and ensure all the angels and lengths appear correct. If you use screws to secure the new fan, you will need the holes pre-drilled. Use the housing brackets as a template and ensure the brackets are secured to the joists.

You can then proceed to installation and follow the manufacturer’s instructions while doing so. Make sure your new fan housing is oriented correctly to support electrical connections and ductwork. Secure the fan motor assembly in place before you proceed to the next stage. Sometimes the silencer baffle may be provided to help with noise reduction.
Step 4: Connect The Wiring And The Duct
Remove the wiring cover and pull out the fan wires. Push the cable through the provided hole to gain full access. Once you can access the wires, strip a little bit of insulation at the end of each wire. Then twist the fan and house wires together while matching colors. Red or black to black and white to white, do not mix the colors. Once you have finished, install the connectors. Fold the wires and put them back into the electrical box, and return the cover. Secure the lid with screws to ensure the wiring is not exposed.
Connect the 4-inch duct to the exhaust port either using the HVAC tape or screws. Do not use ordinary tape to install the flexible duct. Then attach the duct to the housing, either the roof or sidewall using the provided fasteners. Ensure the tubing runs as directly as possible from the fan to the vent. Once you have completed it, you should pull down the insulation jacket to complete your installation. You will have to replace the old vent cap with a new one on the roof. But if you are not comfortable with the tall ladder, you should call an expert to help.
Step 5: Test the New Fan
Now is the moment of truth. After installing everything correctly, get down from the attic and try the fan by switching it on. Listen to the fan; if you can hear it, you are on the right track. If you can hear rattling, it means you forgot one fastener. Some fans are very quiet, so you will have to be very keen to determine if it’s working.
You also need to check the suction power. Hold a small piece of toilet paper or light material near the fan. It should be sucking the material towards the fan. If everything is working correctly, you can then clean out the working area. Don’t forget to boast to all your friends about your impeccable handy work.
FAQs
The bathroom fan installation process is long, and it involves a lot of stages and instructions. Because of the detailed job, there might be questions from people looking to install a new fan. Here are some of the questions that are frequently asked.
Do Bathroom Exhaust Fans Need To Be Vented Outside?
Yes, you are always advised to have your bathroom fan vented outside. Remember, the main job of the fan is to remove moisture that causes mold and mildew from the bathroom and make the air quality around the house better. So if you vent the fan into the attic, you are simply transferring the problem from one area to another. But when the moisture is taken outside your bathroom, the attic and other rooms remain fresh.
How Much Does It Cost To Install A Bathroom Exhaust Fan?
According to what most homeowners say, an average bathroom exhaust fan installation will cost you between $ 240 and $ 541. But the price can go as low as $ 100 or as high as $ 800, depending on a few things. It will depend on the kind of fan you buy, whether it’s a replacement or new installation and if you are hiring a professional or doing it yourself. Be ready to spend an averagely of $ 300 when planning to get a bathroom fan.
Do I Need An Electrician To Install A Bathroom Exhaust Fan?
If you are not an expert, you will need an electrician to help with the wiring part of the installation. Electricity can be dangerous when not handled correctly, so if you don’t know how to handle the wires, hire an electrician. However, if you can follow the installation instructions starting by turning the power off, you will install the exhaust fan without help. So it all depends on you and what you are capable of.
What Is The Best Way To Install A Bathroom Exhaust Fan?
The best way to install a bathroom fan is from the attic. It gives you ample space to work and more control over the wires and other tools. Connecting the duct will also be easy when you have easy access to the roof vent. The best way is also to follow the manufacturer’s instructions because different fans require different things. Gather all the materials and tools before you begin working to make the installation easy.
Conclusion
The process of installing a fan is quite long, and it may take you more than a couple of hours. If it’s not your first time, you will have some knowledge of what to do. It gets tricky when it’s a new installation. Mold, mildew, and moisture accumulation are not ideal; they pose a threat to your health. The moisture can also compromise the air quality in the house. That is why a bathroom exhaust fan is crucial. It keeps all these threats away and ensures you have a pleasant bathroom experience every time. The installation should be your next DIY project but find an expert if you feel like the work is too much.