Replacing a bathroom fan without attic access

How To Replace a Bathroom Exhaust Fan Without Attic Access

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Kevin Jefferson

March 24, 2022

Replacing a bathroom exhaust fan is rarely an easy job – there’s no doubt about that. What is more, it’s even trickier for those who don’t have attic access. 

However, by completing a couple of simple tasks, every homeowner can do this job correctly and safely. In this article, I’ll go over 11 steps that will help you in doing so: 

Replacing a Bathroom Exhaust Fan Without Attic Access – Important Considerations 

Before your start, it is a good idea to familiarize yourself with your local bathroom exhaust fan venting code. You may also want to check our What do Bathroom Exhaust Fans Do? post as well.

Replacing one of these appliances without visiting the roof space can be done in less than an hour if you’re well-prepared and have all the necessary supplies. Consider the following factors before starting: 

Size of the Housing

man replacing bathroom exhaust fan vent

Before buying a new fan for your bathroom, it’s very important that you remove the grille and measure the size of the hole in your ceiling. 

If the model you’re planning to purchase is larger than this hole, you will, obviously, need to take a keyhole saw and cut a couple of inches of the drywall to make the hole bigger. 

In fact, as you won’t be replacing your exhaust fan through the attic, purchasing a larger appliance that will require you to make the ceiling hole bigger will also make removing the old model much easier. 

Retrofit & Low-Profile Bathroom Exhaust Fans

Low-profile bathroom exhaust fan

If there isn’t much room in the ceiling hole, consider getting yourself a so-called low-profile exhaust fan. As its name suggests, an appliance of this type typically sports a smaller (and thinner) housing. 

Obviously, this makes installing it much easier, particularly for homeowners without attic access. 

Another important thing to keep in mind here is that the bathroom exhaust fans advertised as retrofit fans are made to be very easily installed as replacements. 

However, some appliances of this type are manufactured specifically for new construction, and replacing an old fan with one of them can be quite challenging. 

Duct Diameter & Adapter 

Bathroom duct in a wall

Another thing you’ll have to do before buying a new bathroom exhaust fan is to check out the duct size. While the newer models use 6” or 4” ducts, the older ones almost exclusively use 3” ducts. 

The larger ducts used by newer bathroom exhaust fans allow these appliances to move air very efficiently without making too much noise. 

The only way to get the advertised performance out of a brand new bathroom exhaust fan is by using an adequate duct. 

However, homeowners willing to renounce some performance can purchase and install a duct adapter (also called “duct reducer”). This item will let you attach a 6” or 4” duct connector to a 3” duct. 

Is the Fan Venting Into the Attic? 

While doing all of this, make sure to also check the exterior part of the duct and see whether it’s working properly, i.e. whether there is airflow or not. Check on the vent cover as well. 

Remember that installing a bathroom exhaust fan in a way so that it vents into an attic or crawlspace is forbidden by the code. You can find more information on this in my bathroom exhaust fan venting code article. 

Additional Wall Switches & Wiring

Bathroom switch

No additional switches will be needed if you decide to install your brand new bathroom exhaust fan so that it uses your old switch. 

However, if your new appliance has a humidity sensor or a heater and light combo and you want to control these extra features with a separate switch, more work will be required – installing a new switch and running new wiring. 

I recommend leaving these tasks to an experienced electrician. 

Required Supplies

  • Crowbar 

Crowbar (or a pry bar) is a simple but extremely convenient tool that can be of great help in a variety of situations. You can use it to detach the housing from the ceiling joist if required. 

As you’ll be replacing your fan without being able to access the attic, this tool will come in very handy when it comes to disconnecting the housing. 

  • Reciprocating Saw 
Worker using a reciprocating saw

If you find yourself unable to detach the housing with a crowbar, you’ll have no other choice but to use a reciprocating saw. 

Also called a Sawzall, this tool will help you cut the screws or brackets that are keeping the housing attached to the ceiling joists. 

  • New Duct 

As stated above, the only way to get the stated CFM rating of your brand new exhaust fan is by using an adequate duct. There’s a pretty good chance you’ll need to use a 6” or 4” duct. 

Don’t forget that you can also install the aforementioned duct reducer. With it, you’ll be able to connect a 6” or 4” exhaust fan to an older 3” duct. 

  • Foil Tape 
Aluminum foil tape

As you can already guess, this kind of tape is made out of aluminum and is often utilized in the HVAC industry. It is typically used to connect the duct connector, which is located on the fan’s housing, to the duct itself. 

  • Power Drill 

You will definitely need a good power drill for this job. Whether it’s cordless or corded, this convenient tool will help you properly secure the bathroom exhaust fan housing. 

  • Quick Connects or Wire Nuts 

As their name suggests, you will use these to quickly and easily hook up the wiring. 

Replacing an Exhaust Fan Without Attic Access – A Step by Step Guide

Tile bathroom

In this part of the article, I’ll be taking a detailed look at 11 steps that should help you easily replace your bathroom exhaust fan if you have no attic access: 

Step #1 – Trace Out the New Housing 

The very first thing you’ll need to do is to trace out the housing of your new venting appliance onto the ceiling. As I already mentioned, there’s a good chance your new fan won’t fit into the ceiling hole, so maybe you’ll need to enlarge it. 

The easiest way to tackle this task is by using a keyhole saw. If you don’t have this tool, you’ll be pleased to hear that it’s quite cheap – you can get one for under $10. If you want to make this task even easier, get yourself a powered multi-oscillating tool. 

Those who want to make a hole before buying the actual fan can easily get the housing’s dimensions from the manufacturer’s website. 

Tracing out the new housing in an adequate orientation is absolutely crucial. If you cut the new exhaust fan in a way so that the duct isn’t in the right position, or if you cut it over a ceiling joist, you’ll probably make some serious damage to your ceiling drywall. 

Step #2 – Turn Off the Power 

Prior to replacing one of these appliances, you will, obviously, have to shut off the power in order to be completely safe. Go to your panel box and locate the bathroom breaker. 

One thing that will show you that you’ve probably turned off the correct breaker is seeing that your bathroom light and outlets have no power as well. However, to be completely sure, verify that the power is genuinely turned off by using one of those cheap non-contact voltage testers. 

Once you’ve turned this device on, touch the wiring with it and it will give you a signal – a visual or an audio one – if the power is still on. 

Step #3 – Remove the Grille 

Bathroom fan grille

The next step you’ll have to take is probably the easiest one – removing the exhaust fan grille (or cover). With your fingertips, pull down on the grille until there’s some space between it and the drywall. 

Once you’ve done that, you will notice two metal clips – their job is to keep the grille attached to the exhaust fan housing itself. 

To release these metal clips from the fan’s housing, just squeeze them together. After that, simply pull down the cover. 

Step #4 – Remove the Motor-Fan Assembly 

Step four involves disconnecting the housing from the motor-fan assembly. This is because the housing of a bathroom exhaust fan has to be attached to the ceiling joists separately. After that, you just have to “insert” the motor-fan assembly into it. 

If you really don’t want to replace the entire housing, there’s a good chance you’ll be able to purchase an identical motor-fan assembly and replace only that part. 

While you may have to remove a couple of screws, this task often consists of just using a screwdriver to free the aforementioned assembly from the housing – usually, it’s just clipped in. 

Moreover, some appliances of this type feature electrical plugs within their cases – that’s where their motor-fan assemblies are plugged into. It goes without saying, but if this is the case with your fan, you won’t be able to remove the motor-fan assembly before unplugging it first. 

If your model doesn’t have this plug, on the other hand, you will have to disconnect the wiring manually. 

Step #5 – Remove the Old Housing 

Once you’ve completed step four, you’ll be able to remove the primary exhaust fan housing from your ceiling joists. 

However, as I mentioned above, this part of the job can be skipped completely if you opt to install the same model of a bathroom exhaust fan. 

The housing of the fan should be connected to the ceiling joists by a couple of nails or screws. Besides those, you may also encounter a metal bracket, which is typically adjustable and sometimes fastened into the ceiling joists. The housing is usually secured to this metal bracket. 

Depending on your level of access and the manner in which the housing is installed, you may have to use a crowbar or a reciprocating saw to detach the housing from the joists. Be very cautious while doing this – you don’t want to damage the joists. 

Step #6 – Disconnect the Wiring & the Duct 

At this point, there’s a good chance you’ll have to temporarily push the fan housing into the ceiling. As you can already guess, doing this provides access to the duct and allows you to remove it from the housing assembly. 

Whether you will or won’t have to do this depends on the duct’s length. In some cases, it is completely possible to detach the duct after removing the housing from the ceiling. 

Most of the time, the duct is attached to the bathroom fan with some foil tape – you’ll just have to cut it. After that, carefully pull down the vent duct and then proceed onto removing the wiring from the fan housing. 

While removing your home’s electrical wiring from the fan’s casing, you may encounter: 

  • Wiring Compartment Lid – In most cases, this will be a small cover with just one screw. 
  • Romex Grommet – This would be a small and circular piece of plastic whose job is to protect the wiring from the sharp metal edges of the housing. 
  • Quick Connects or Wire Nuts – Pull out the wire to remove the quick connects. To remove the wire nuts, on the other hand, you just need to turn to loosen. 

Once you’ve removed the vent duct and the electrical wiring, you should be able to fully remove the old fan housing from the hole in your ceiling. 

Step #7 – Pull the Wiring Through the New Housing 

The next thing you’ll have to do is to pull the wiring through the new housing. Obviously, this part of the job needs to be done before securing the case to the ceiling joist. 

And in order to pull the wiring through, you’ll have to remove the wiring lid on the new housing. This step can be ignored if your brand new bathroom exhaust fan comes without a wiring cover. 

Once you’ve successfully pulled the wiring through, use protective bushings or grommets to secure it. This will protect it from getting harmed by the metal edges. 

A bare metal edge can seriously damage the wiring, so it’s no wonder that protecting it with bushings or grommets is standard practice. There’s no guarantee you’ll be getting these grommets together with your brand new appliance in the packaging, though. 

Step #8 – Connect the Duct to the Housing 

A small piece made of plastic, the duct connector has the purpose of connecting the bathroom exhaust fan with the duct inside the ceiling. 

Almost all devices of this type feature a part that is called the flapper. This flapper is opened whenever there’s airflow and closed when the appliance is not in use. 

In order to ensure that the flapper will be closed when it should be, it’s very important to install the duct connector in an adequate orientation. 

The installation can be done in two ways. If you don’t have attic access, your best bet is to simply put the duct connector into its place before inserting the fan housing into the ceiling hole. This should, however, be done after you’re done with the “pulling the wiring” task described above. 

Unless you’ve somehow managed to make your ceiling hole bigger, you won’t be able to pull the wiring through and attach the duct after you’ve installed the housing. Things are somewhat less tricky with flexible ducts, though. 

Once you’ve used some metal foil tape to secure the duct to the duct connector, simply tighten everything up and carefully push the fan housing into the hole in your ceiling. You may also want to read our guide on how to oil a bathroom fan.

Step #9 – Secure the Housing to the Joists 

The easiest way to complete this particular task is through the use of nails or screws. In order to prevent the exhaust fan from falling down, you’ll have to attach it securely to at least one joist. 

Another way to install one of these appliances onto the joist is by using an installation bracket. Your particular model may or may not come with one. Unless you try to make your ceiling hole bigger, this probably won’t be a viable option anyway as you don’t have attic access. 

Are there any metal tabs on the casing? If so, you may have to remove (or just bend) them so that the fan casing can properly fit into the ceiling cavity. 

Step #10 – Connect the Wiring 

The next step involves connecting the wiring, which should now be already pulled through the casing. 

A vast majority of new bathroom exhaust fans come with quick connects and these allow homeowners to easily put the wires into corresponding connectors. Once you’ve done that, just push all of the wires into their compartment and cover it with the lid. 

Step #11 – Reinstall the Grille & Turn On the Power 

Empty bathroom

Completing the last step is as easy as it gets – you only have to reinstall the fan’s grille. Do you remember those metal clips I’ve mentioned in step #3? Just squeeze those together and insert them into the holes on the casing. 

Check whether your brand new venting appliance is working correctly by flipping the breaker back on. If you’ve opted for a quiet bathroom exhaust fan, determining whether it’s currently in operation or not can be somewhat tricky. 

Fortunately, there’s a simple solution to this issue – take a piece of toilet paper and check if there’s suction by holding it close to the fan.

Check out our post on insulating a bathroom exhaust fan duct and our post on cleaning a bathroom exhaust fan as well.

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