Let's face it, replacing a bathroom fan isn't always a simple job.
And if you don't have attic access—it can be even trickier.
But homeowners can do it safely and correctly with a few simple steps such as tracing out your new bath fan housing onto the ceiling and other simple measures.
It is also essential that you have the correct duct adapter if you plan on connecting an older 3-inch duct to a modern bath fan.
You may also be interested in our guide on how to install a new bathroom fan on the first floor since it is related.
In this HomeInspectorSecrets.com guide, I will go over...
- Pulling the wiring through the housing before you secure it to a joist
- Why you should secure the bath fan to at least one joist
- Using foil (metal) tape to connect the new duct
- Always install a Romex connector or grommet to protect the new wiring from damage
Keep reading to learn the 12 steps to replace a bathroom fan without going into an attic!
What You Need To Know About Replacing Exhaust Fans Without Attic Access?
Replacing a bath fan without going into an attic can be done in 30min to an hour if you have all the parts ready, and you prepare for the job. Here are a few important considerations before you start:
Before even purchasing a new bathroom exhaust fan, it may be a good idea to remove the grille, and measure the exhaust fan housing in-between the drywall.
If your new exhaust fan is larger, you will need to cut some of the drywall with a keyhole saw such as an inch or two.
In fact, since you won't be using an attic to replace the fan, if you buy a larger bathroom fan that requires you to widen the ceiling hole, it will make it easier to remove the old bathroom fan.
Low Profile & Retrofit Exhaust Fans
If you don’t have much space in the ceiling cavity, you can consider the purchase of a low profile bathroom exhaust fan — these fans have a smaller housing (especially thickness) than regular bath fans and will make the installation easier without attic access.
Also, anytime a manufacturer advertises as a retrofit bath fan means that they designed it to be easier to install as a replacement. Some bath fans are designed for new construction, and will be significantly more challenging to install as a replacement.
Duct Diameter & Adapter
This is also a good time to check the fan duct size. Older bathroom fans almost always use a 3-inch duct. But newer bathroom fans frequently use a 4-inch or 6-inch duct diameter. The larger duct allows new bath fans to reach high fan speeds and move more air with less noise.
If you want to get the advertised performance out of the new bath fan, you will have to install the required duct. But if you are willing to sacrifice some performance, you can install a duct reducer (duct adapter) which will connect the 4-inch or 6-inch duct connector to your older 3-inch duct.
Does The Bath Fan Vent Into The Attic?
This may also be a good time to check the duct on the exterior to make sure the vent cover is working properly and that there is airflow.
If the bath fan is venting into a crawlspace or attic, it isn't allowed by code. You can read more details on whether bath fans can vent into attic spaces here.
Additional Wiring & Wall Switches
If you want the new exhaust fan to use your old switch, then no additional switches will be needed.
But if your new exhaust fan has a light, heater, or humidity sensor, and you want to control it with a separate switch, you will need to run some new wiring and install a new switch which requires more work.
If you have to install new wiring, we recommend you have an electrician install the new bathroom fan.
Supplies You'll Need To Replace A Bath Fan Without An Attic
- Pry Bar: A pry bar or 'crow bar' is a simple tool that can break loose the housing from the ceiling joist if needed. Since you are replacing a bathroom, you will need to disconnect the housing without going into the attic, and a pry bar can help do the job.
- Reciprocating Saw: If a pry bar doesn't work to break loose the housing, you may need to use a reciprocating saw or sawzall to cut the brackets or screws holding the housing to the ceiling joist(s)
- Foil (Metal) Tape: Foil tape is a type of aluminum tape that is used in the HVAC industry. This metal tape is used to connect the duct to the 'duct connector' that is on the housing.
- New Duct (Or Duct Reducer): Your new bathroom fan may require a 4-inch or 6-inch duct if you want to get the stated CFM and performance out of the new fan. This guide doesn't go over the details of installing a new duct, but you also have the option of installing a duct reducer to connect an older 3-inch duct to a 4" or 6" ducted fan.
- Power Drill: Whether it is corded or cordless, a powered drill is highly recommended for this job, though you may be able to secure the bath fan housing with nails and a hammer.
- Wire Nuts Or Quick Connects: You will need some wire nuts or quick connects to hook up the wiring.
Read Our Guide On How To Remove Bathroom Fans (8 Step Guide)
How To Replace An Exhaust Fan Without Attic Access (12-Step Guide)
- Trace Out The New Housing On The Ceiling
- Turn Off Power To The Bathroom
- Remove The Grille
- Remove Old Fan-Motor Assembly From Ceiling
- Remove The Old Housing From Joists
- Disconnect Duct & Wiring From Old Exhaust Fan
- Pull Wiring Through New Housing
- Attach Duct To Housing
- Secure Housing To Joist(s) With Screws Or Nails
- Connect The Wiring (Hot, Neutral, And Ground Wires)
- Reinstall Grille On New Housing
- Turn On Power And Test It
Step 1 - Trace Out The New Housing On The Ceiling
It is highly recommended that homeowners trace out the new bathroom fan housing onto the ceiling prior to the installation. For one, you may need to enlarge the ceiling hole to fit the new bathroom fan.
And if you cut out the large drywall hole first, it will make the removal of the old fan easier since you don't have attic access, but it isn't required.
The simplest way to widen the drywall hole is using a keyhole saw which you can buy for under $10. But a powered oscillating multi-tool will make this job super-easy.
If you want to do this step prior to buying a new bath fan, you can get the dimensions of the housing from the manual or manufacturer's website.
It is essential that homeowners trace out the new housing in the correct orientation. If you trace out and cut the new bath fan over a ceiling joist, or where the duct is not in the right location—you may damage the ceiling drywall and have to re-do it.
Step 2 - Turn Off Power To The Bathroom
The first step in replacing a bathroom ceiling fan is to shut off the power. Locate the breaker for the bathroom at your panel box.
The bathroom outlet and light will likely have no power as well, so that is a good indicator that you have turned off the right breaker. To be sure, you can use a $10 non-contact voltage tester to verify that the power is truly off.
Simply turn the voltage tester on, and touch the electrical wiring (or anywhere near it) and the tester will start beeping or light up if the power is on.
Step 3 - Remove The Grille
Removing the exhaust fan cover or grille is very easy to do. Just pull down on the plastic cover with your fingertips until there is a small gap between cover and drywall.
There will be two metal clips (like in the picture above) that attach the cover to the housing.
Squeezing the metal clips together will release the clips from the housing, and then you just pull off the cover.
Read Also >> How To Vent A Bathroom Fan Through The Wall?
Step 4 - Remove the Old Fan-Motor Assembly From Ceiling
The motor-fan assembly will need to be separated first from the housing. The exhaust fan housing is separately attached to the ceiling joists. The motor-fan assembly is basically an insert.
And if you want, you may be able to buy the exact same fan-motor assembly and just replace that, rather than having to change the entire housing.
There may be a screw or two that needs to be removed, but quite often, all you have to do is use a screwdriver to free the motor from the metal housing because it is clipped in.
Some bathroom vent fans will have an electrical plug within the housing that the motor is plugged into. You will have to unplug the motor before you can pull out the fan-motor assembly.
If there is no plug, the wiring will have to be manually disconnected, possibly by removing the wire nuts after you have removed it.
Step 5 - Remove The Old Housing From Joists
Now it’s time to remove the main fan housing from the ceiling joists. Unless you are installing the same model bathroom fan, the old housing will likely need to be removed.
There should be a few screws or nails connecting the fan housing to the ceiling joists. An adjustable metal bracket may also be screwed into the ceiling joists — and the fan housing secured to the bracket.
Depending on how the housing is installed and your level of access, you may need to use a reciprocating saw or pry bar to break loose the housing from the joist(s). Be careful that you don’t damage the wood joists.
Step 6 - Disconnect The Duct & Wiring From Old Exhaust Fan
When the housing is free from the ceiling, you may have to temporarily push the metal housing into the ceiling. Once it is pushed upwards, you will have access to the vent duct that will need to be removed from the housing assembly.
You may also be able to pull the housing out of the ceiling, and then disconnect the duct. It all depends on how long the duct is.
The duct is usually fastened to the exhaust fan using foil tape or a simple zip tie which will have to be cut. After removing the vent duct, you will need to remove the home’s electrical wiring from the housing.
To remove the wiring, there may be a...
- Wiring Compartment Cover: These small covers can usually be removed with a single screw.
- Romex Connector Or Grommet: A grommet is simply a circular piece of plastic that protects the electrical wiring from getting damaged by a sharp edge where it passes through metal.
- Wire Nuts Or Quick Connects: For wire nuts, you just turn to loosen. For quick connects, you just pull out the wire.
After you have removed the home’s electrical wiring and the vent duct, you can now completely remove the old housing from the ceiling cavity.
Read Also >> What Is The Building Code For Bath Fan Venting?
Step 7 - Pull Wiring Through New Housing
Before you secure the new housing to the ceiling joist, you will need to remove the wiring cover on the new housing so that the wiring can be pulled through.
If the new bath fan doesn’t have a wiring cover, you can ignore this step.
Once you pull the wiring through the housing, you should secure it using a protective grommet or bushing so the wiring doesn’t get damaged on a metal edge.
It is a standard practice to use grommets (or bushings) to protect wiring from rubbing against a bare metal edge. Your new exhaust fan may or may not come with one.
Step 8 - Attach Duct To Housing
The duct connector is a small plastic piece that connects the duct inside the ceiling to the new bathroom fan.
The duct connector has a flapper that is closed when the fan is not in use, and then opens when there is airflow. Always make sure that the duct connector is in the correct orientation, which means the flapper is closed when level.
There are two ways to install the duct connector. The best way to connect the duct adapter without attic access is to first connect it to the duct prior to inserting the housing into the ceiling.
This should also be done after you have pulled the wiring through the housing.
You won't be able to attach the duct and wiring after you install the housing unless you have widened the ceiling hole. If the duct is flexible, it should be able to be pulled out of the ceiling by at least several inches.
You should secure the duct to the connector using metal foil tape (as recommended by the Energy Department), and once tightened, you can push the entire housing into the ceiling.
Step 9 - Secure Housing To Joist(s) With Screws Or Nails
The most common way to secure the housing to the joist is to use screws or nails.
It is important that the bath fan is secured to at least one joist otherwise it may fall down.
Your new bathroom fan may also come with an installation bracket which is installed onto the joist, and then the housing is installed onto the bracket. This may not be workable if you don't have attic access unless you widen the drywall hole.
Also, if there are metal tabs on the housing, you may need to bend or remove these tabs in order for the housing to fit into the drywall hole.
Read Also >> How To Vent A Bathroom Fan Through A Soffit?
Step 10 - Connect The Wiring (Hot, Neutral, And Ground Wires)
After you have secured the housing to at least one joist—you will need to connect the wiring. The wiring was already pulled through the housing but not yet fully connected.
Some new exhaust fans will have quick connects that allow you to insert bare wires into the connectors which is very easy. Other exhaust fans will require you to twist together the bare wires, and then twist on a wire nut.
Once the home’s wiring has been connected, push the wiring into the wiring compartment and fasten wiring cover so it is out of the way.
Always remember to connect the wires according to color…
Wire nuts are color coded based on the size of wire that they can be used for as mentioned by Wikipedia. If your new fan doesn’t come with wire nuts, then make sure to buy properly sized wire nuts.
- Hot Wire (black to black)
- Neutral Wire (white to white)
- Ground Wire (green to green OR green to bare copper)
If your new exhaust fan has a heater, light, or humidity sensor, the color codes may be a little different. For example, if your bath fan has a heater, there may be a black to red wire connection instead. Look to the manual for the wiring diagram so you can be sure you are connecting the right wires.
Step 11 - Reinstall Grille On New Housing
Now is the time to reinstall the cover or grill. Just like when you removed it, you will have to insert the clips into the holes of the housing — squeezing the clips.
Step 12 - Turn On Power And Test It
Flip the breaker back on, and check to see if the fan is working.
If you have a very quiet bathroom fan, it may be difficult to know that it’s on.
You can take a small square of toilet paper and hold it up to the fan to see if there’s suction.
Read Also: Is Your Bathroom Fan Leaking When It Rains?
Final Thoughts On Replacing Bathroom Vent Fans Without Attic Access
Replacing a bathroom exhaust fan without attic access can be done correctly if you are aware of the common sticking points. It is also a good idea to seal around the housing with caulking to prevent air infiltration.
The biggest challenges of installing a bathroom fan without attic access will likely be connecting the vent hose to the housing assembly as well as the wiring.
Just remember you will need to connect the duct and wiring before attaching the housing to a joist. You may need to connect the duct and wiring by pulling them out of the ceiling.
It also may be easier to push the housing deep into the ceiling cavity, and then pull through the wiring and connect the duct. After it is connected, then you can screw in the housing assembly to the joist.