How To Install A Bathroom Fan Without Attic Access

Bathroom exhaust fans offer several benefits. Their primary purpose is to clean the indoor space by ventilating the stale and dirty air to the outside.

They also prevent moisture buildup from affecting the air quality in the bathroom. The bathroom exhaust fan also keeps the temperature relatively cool without the need for air conditioning.

With that in mind, there may be several reasons why you would want to replace an old fan. While it is easier to install a bathroom fan when you have attic access, that is not the only way. You can just as well install a bathroom fan without attic access.

In this article, we will thoroughly explain how to install a bathroom fan without attic access. We’ll start by telling you how to remove your old bathroom fan, list the tools you need to get started, and guide you through the installation process of your new fan.

Tools Needed To Install The New Bathroom Exhaust Fan

Below is a list of the tools you will need. Depending on your setting and new fan type, you may not need all of these. You can get all of this from any hardware store. (I’ll link to Amazon since they are the quickest delivery.)

Things To Consider Before Installing The New Exhaust Fan

Before installing, and preferably buying, a new fan, you need to pay attention to the following details.

Fan Duct Size

If your new fan is the same size as your old one, the process will be quite straightforward. You should measure the size of the old fan’s housing. Measuring the exhaust fan cover is not enough; you should remove the cover and measure the space inside the ceiling drywall.

Exhaust Fan Size

If you already bought a new exhaust fan that doesn’t match the housing size, some adjustments to the ceiling hole will be necessary.

Generally, the airflow of fans is measured in CFM, or cubic feet per minute. The recommended size of the fan largely depends on the size of your bathroom.

Manufacturers use different formulas to determine the recommended size. Small bathrooms typically use 50 CFM fans while large bathrooms use 100 CFM. You can always ask your vendor for recommendations.

Exhaust Route

Exhaust fans should generally vent to the outside. With attic access, the fan can vent through the roof or the gable wall.

Without having access to the attic, you can either create attic space by opening up the ceiling or vent the fan through an exterior wall.

If for any reason, you can’t create an exhaust route for your fan, it’s always an option to call a professional to help you through this. You can then install the fan by yourself if you like.

Wall Switches

If you want your new fan to operate on the existing switch, you can skip this part.

However, the new exhaust fan may include a light of its own or other additional features such as a humidity sensor. As a result, they will require at least two wall switches instead of one. In this case, you have to set up the new electrical wiring accordingly.

Removing The Old Fan

You obviously have to remove the existing fan before you install the new bathroom fan. The process is quite simple. Here is how you can take off your old fan.

Turn The Power Off

During the process, you will deal with the many fan wires. The wise thing is to shut down the power in the bathroom before you start anything. You should do this from the breaker box.

Once the power’s off, detach the grill or plastic cover and make sure there is no power using a circuit tester.

Take Off The Old Fan Motor

With the old exhaust fan cover removed, you can now detach the fan motor. To do that, remove the few screws and wires attached to the motor.

Detach The Bathroom Fan Housing

The exhaust fan housing can be held in place in different ways. If it’s connected to the ceiling joist using metal clips or brackets, you can cut the brackets from below using a reciprocating or keyhole saw.

The fan’s housing may be connected to the ceiling joist with mounting screws. In this case, you can just remove the screws. This process is a little easier when the attic space is accessible, but it shouldn’t take you much time otherwise.

Disconnect The Electrical Wiring

Next, you should detach the house wires and remove any electrical wiring connections that are still there.

Remove The Old Bathroom Fan

All that is left is to remove the duct from the exhaust fan and the fan housing from the ceiling hole. With this, your old fan is no more.

How To Install A Bathroom Fan Without Attic Access

Doing this can be a bit tricky. However, by having the necessary tools and following the right procedures, it should be done with no problem.

Prepare The Ceiling Hole

Before you pick up your tools and start attaching things, have a closer look at the new exhaust fan to check if it fits the ceiling hole.

If the ceiling hole seems to be too big, you’ll have to patch the ceiling using drywall. If you like, you can improve and fix the patched areas with spackling paste. The hole in the ceiling should be a little larger than the fan diameter, but by no more than 1 inch on each side.

In this case, chances are, your new fan may not be attached to all the ceiling joists in the housing. Since exhaust fans aren’t very heavy at all, make sure that the bathroom fan can be attached to at least one joist.

On the other hand, the ceiling hole may be too small for the new bathroom fan. If that’s the case, use a keyhole or reciprocating saw to cut the ceiling just enough for the new fan to fit. Again, make sure to leave a little space between the fan and the ceiling.

Attach The Connector

Using the clamp or the HVAC, place the duct connector onto the ceiling duct. The main fan housing needs to be lined perfectly, so it’s important to attach the duct in the right position. Each new exhaust fan comes with instructions that you can follow so everything is in order.

Next, using mounting screws, attach the connector to the ceiling edge to line it up with the exhaust.

Attach The New Fan Housing Assembly To The Ceiling Joists

By looking at the ceiling hole around its edges, you’ll be able to better understand where and how the fan will fit. Then, secure the new housing assembly to the wood joists in the ceiling. Again, if the new size doesn’t match, it is enough to attach to a single joist. Don’t worry; the fan is not likely to fall off.

Run The Wires

This is the most crucial part, and you need to do it very carefully to avoid any electrical issues.

Start by removing the knockout plug as well as the covering on the wires from the new bathroom fan using a screwdriver. Then, attach a cable clamp on the wiring cover and run the house wires through it.

Now, each house wire needs to be attached to the corresponding fan wire. Use wire nuts or something similar to make this easier. Typically, ground wires are either bare copper, green, or yellow and green wires. So, attach your fan’s ground wire to the corresponding bare or green wire.

Similarly, attach the fan’s black wire, also known as hot wire, and white wire to the corresponding house wire. Now that the wires are all connected, push them into the housing and seal the wiring cover using screws.

Attach The New Fan To The Duct

All that is left to do is to put the bathroom exhaust fan in place. The wood supports in the housing needs to be connected to the fan.

Once the fan is in place, you can use caulk or foil tape to seal the gaps and prevent air leaks. Before attaching the fan cover, you can check if the fan is working. If it is, you can finally turn on the circuit panel box.

If you’ve done everything correctly, your exhaust fan should be working perfectly. Finally, reattach the fan grill cover by pushing it towards the fan.

Final Thoughts

Now that we’ve seen how to install a bathroom fan without attic access, you can prepare your tools and get to work. The process is quite simple, so you can do it on your own to save the cost of hiring a professional. We also explored the factors to consider before buying and installing the fan, so make sure everything is accounted for before you start the installation.

However, depending on your bathroom’s specific conditions, things may prove difficult. For instance, creating an exhaust route for your fan and setting up a new electrical system may prove troublesome. In this case, you can always call a professional to make sure everything is done correctly.

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