How to Vent a Bathroom Fan

        The bathroom could be an ideal place for mold to have root, given the moist and warm condition of the place. Perhaps you don’t want that to happen; the best bathroom vent fan could be a good idea to keep the humidity level in the bathroom safe and mold-free.


        Also, these exhaust fans may be useful in the elimination of bathroom odors by improving the quality of indoor air circulation. Consequently, you get to have a swell bathing time without feeling uncomfortable or nauseous. Read on as we enlighten you on the best method to vent your bathroom fan.

Tools and materials you may need include:

  • Bathroom exhaust fan
  • Cordless power drill
  • Safety glasses
  • Flexible duct
  • Stud finderDrywall jab saw, or hole saw
  • Exterior grade silicone caulk
  • A ladder to access the attic
  • Respirator or dust mask
  • Flashlight or portable light
  • Pencil
  • Roof vent cap or round wall vent cap (depending on whether you’re venting to the sidewall or roof)

Tools and materials you may need include

Just before you start

        The two major issues that you may be faced with when taking up this task include power and venting to the outside. The common power rating recommended for most residential bathroom fans is AC 120V electrical lines. They usually come with instructions on how to find the live electrical cables and run them to the right location.

        Venting basically means the process by which the air is drawn to the exhaust fan, passes through a flexible duct that is connected and expelled out of the house via a hole created in the roof or side of the house. For a new installation, the bathroom does not have ducting. However, you should be able to route the flexible tubing outside as long as you’re able to access the attic above the bathroom ceiling.

        Ensure that the electricity to the ceiling light is turned off. You can do this by switching off the circuit breaker located at the service panel. Use the ladder to climb up the attic after locating its door bringing with you your respirator and flashlight.

Establish or find the Power Source

        In the case where the bathroom vent fan will be installed in the ceiling, you may have power running to the point where you plan to install the vent fan. You may also be able to share the lighting circuit of the bathroom with the fan, which depends on your local electrical code. The lighting circuit of the bathroom usually supplies power to the ceiling light of the bathroom. Another option is you can replace the light with a fan/light combination.

        Alternatively, you may be required by the code to run a dedicated circuit solely for the vent fan. Then, you can run a new cable to the ceiling of the bathroom from the service panel. Perhaps, you don’t feel comfortable doing that yourself, it might just be the right time to get an electrician to complete the task for you.

Locate the Vent Point (the Reference hole)

        The exhaust air generated by the fan must exit outdoors, so you may need to run a duct to either the sidewall or the roof from the fan. To avoid roof leaks, you may want to run the flexible ducting along the sidewall.

        Ideally, the use of the rule of thumb for the vent location is to help you choose the right spot that is:

  • In the bathroom interior, not in a hallway
  • A direct path from the fan to the outside
  • Six feet long or less from the bathroom fan extending to the exit point
  • As straight as possible to avoid sharp bends that can hinder airflow
  • Located close to the shower, tub, or the shower/tub combination, bearing in mind that this is the area that produces the most moisture

Then, you can now drill a locator hole at the center of the intended location for the vent.

Cut the Exterior Vent Location

        Access either the sidewall or the roof of the house, depending on where you intend to expel to the exterior.

        Get your vent cap (for roofs) or round vent (for walls). Also get your pencil, silicone caulk, cordless drill, and reciprocating saw. Place the vent cap or round vent across the locator hole. With the use of a pencil, draw out a circle where the cap or vent is meant to fit.

        Using the locator hole as a start point for the reciprocating saw blade, cut out the circle. Afterward, use screws to attach the roof cap or round vent. Remember that you need to ensure a watertight fit. This can be achieved by using silicone caulk.

Cut the Interior Opening for the Fan

        From below, locate the joists in the ceiling using the stud finder and mark it lightly using a pencil. In case your fan has a paper template, you can mark out the intended location of the vent fan in the ceiling using the template.

        Maybe there is no template; you can make use of the metal housing itself without the fan. Most bathroom fans screw to the side of the joist directly. So, to make the cut lines, you can place the metal housing or template parallel to a joist. Carefully cut out the drywall with a jab saw.

Attach the Fan to the Joist

        Get your flashlight, screws, cordless drill, and housing of your bathroom fan into the attic. Now place the fan in the cut-out hole in a way that the bottom of the drywall ceiling meets and aligns with the bottom edge of the fan. You most likely cannot see the ceiling from this position, so you would need a partner to help you out.

Attach the Fan

        With the use of the cordless drill, begin to screw the fan into the side of the joists. For your information, your fan may come with suspension brackets if you cannot use the side of a joist as the attachment point. Alternatively, if it doesn’t come with either of the two, you can get them separately. The brackets ensure the fan is suspended in the right position (adjacent to a joist).

        You should also fit the electrical cable while you’re still in the attic through the side of the housing so that the cable extends at a length of roughly 7 inches into the housing.

Route the Bathroom Fan to the Exterior

        Get down to the bathroom to ensure the vertical alignment of the fan is just fine. After that, get your flexible ducting into the attic and attach it to the fan and the vent. Ensure a smooth and direct run of the tubing.

Attach the Fan to the Housing

        Using the instruction manual provided, you should insert the fan into the housing. Get the end of the electrical cables and hard-wire into the unit using the color match. Usually, the green or bare wire is attached to the metal housing side for grounding.

        Lastly, plug in the fan grille to the housing face and turn on the circuit breaker. Then you can go and test the fan in the bathroom.

Installation Tips to consider

  • When working in the attic; the wallboard ceiling will definitely not support your weight. So to avoid any hazard, ensure to walk along the joists.
  • Also ensure the fan is properly installed, as this may result in loud and annoying sounds. Lack of proper insulation during installation may also result in heat escaping into the attic.
  • Ensure that the gap beneath the bathroom door is not tightly sealed. Make an allowance of a 3/4-inch gap for easy and quick replacement of so that the air exhausted by the fan.
  • Ensure that the vent louver at the exterior operates appropriately so that when the fan is not running, it closes fully. When the vent fan is not in use, this will prevent cold air from seeping back into the house.
  • For extra high bathroom ceilings, you may need a vent fan with extra capacity.
  • The best place you can situate a vent fan is near an area you can get enough moisture. For instance, over the sink or close to the shower.

Installation Tips to consider

        If you have an open bathroom, you can situate the vent fan midway between the toilet area and tub/shower. For a very small bathroom, having the fan centrally positioned in the room is just fine. However, in case the toilet is enclosed with a door, you might want to consider having two vent fans.


        Many folks think that the main function of the best bathroom vent fan is to remove odors from a bathroom. This assumption is wrong! Bathroom vent fans can also help you get rid of moist and warm air, which can result from using bathtub or shower. And as we have seen, there are two basic ways to vent your bathroom fan; either through the roof or sidewall.

        Having provided you with the things you may need and the procedures to follow to achieve a successful venting, then we believe you can have it done all by yourself and save some money on professional service. Good luck!

Jessica Grace

Hey there! I am Jessica Grace - Main editor of I'm a writer about home improvement, kitchen, and bathroom, and hope to share with everybody. I have a passion for exploring and listening to music during my free time. Thanks for stopping by and I hope you found what you were looking for!

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