5 Installation Tips for Bathroom Ventilation Fans

Someone wiring a ceiling vent.

Bathroom vents are great for cleaning up fogged windows and preventing moisture issues that sometimes lead to mold and mildew growth. But although vents are essential in the bathroom, many homeowners choose not to install them because it can be an intimidating process. Luckily, installing a bathroom vent is not as hard as it may seem. Here are five tips on properly installing a bathroom fan to help get you started.

1. Select The Right Vent

Bathroom vents are rated based on the amount of air they move per cubic feet. This measurement is known as cubic feet per minute, or CFM. By rule of thumb, the air inside your bathroom should be circulated eight times every 60 minutes. If your bathroom is 35 square feet, for example, then you should install a 50 CFM fan. The higher the CFM rating, the faster the air will be removed. Further, if your ceiling is higher than eight feet, you will need a stronger fan to help circulate the air. If you are not sure about what size fan you need, there are online bathroom vent fan calculators that can help you out.

2. Always Vent Outdoors

A roof with a ventilation pipe coming through it.

Regardless of the venting option you pick, you should always vent the bathroom outdoors and never into an attic or crawlspace. Venting indoors can build up moisture in the air, which often results in the growth of mildew or mold. You can easily prevent this hazard by venting the fan outdoors. Generally speaking, there are two different methods of venting a bathroom fan: sidewall and roof.

The sidewall option vents the fan through the side of the house. This option is ideal if the bathroom is on the first floor of a multi-story home and the roof is not easily accessible. The second option vents the fan through the attic and out the roof. A roof cap is installed above the shingles to help prevent unwanted moisture from entering the line.

3. Choose the Correct Vent Placement

It's best to install the vent somewhere between the toilet and the shower. When you are installing a bathroom fan for the first time, it can be difficult knowing where to cut above the ceiling. You want to place the vent in between ceiling studs, avoiding any joists or studs in the process. A great way to get a perfect cut is to drill a reference hole. Using a long bit, drill a hole that extends through the ceiling and into the space above. Then, go up into the attic and adjust the reference hole until you are centered between boards.

You can then use the vent housing to measure around the final hole and cut out the shape from inside the bathroom. This will ensure that you do not cut into any supporting beams from above.

4. Secure the Vent

You want to ensure the vent is nicely secured to the wall so that it does not accidentally fall when in use. The best way to secure a vent is to screw it into the ceiling joists. Most fans come with an adjustable bracket that needs to be extended until it reaches both joists. You can then use a 1-1/2-inch drywall screw to secure the vent to the wood.

5. Use Smooth and/or Insulated Ductwork

A man insulating a ventilation pipe.

It's recommended to use smooth ductwork in bathroom vents as this will help reduced bends and overall length. If you live in an area prone to cold weather, consider installing insulated ductwork, which helps reduce the amount of condensation that builds up on the outside and inside of the material. When it comes to attaching pieces of ductwork together, opt for foil duct tape instead of the traditional variety. This kind of tape is more durable and stands up better to moisture in the long run. Foil tape should also be used on all joints and over screw holes to tightly seal the vent.