Buying and Installing a Garage Exhaust Fan

the side of a metal building with a vent and chimney
  • 5-10 hours
  • Advanced
  • 100-200
What You'll Need
Exhaust fan
Drywall saw
Masonry saw of jigsaw
Housing frame 2x4s
Wood nails

Most people never think about the ventilation in their garage, and that's a bad idea. Paints, chemicals, and other items that are commonly stored in the garage create fumes that can become dangerous. Good air circulation is essential for every part of your home, and that's especially true for the garage.

Installing a garage exhaust fan is the most effective way to get healthy air circulation to protect against deadly carbon monoxide and protect your car from being stored in conditions that are too hot. Ventilation helps release some of the hot air that builds up in garages, and that helps keep your car in better condition for much longer.

Buying an Exhaust Fan

Is your garage also going to be a man cave or a home workshop? The type of exhaust fan you buy for your garage depends on how much time you're going to spend in this space. A large shutter fan will keep the air quality in this space high. A large exhaust fan like this prevents condensation and provides an escape for heat. It keeps the air well-circulated so you have more breathable, healthy oxygen, which is exactly what you need if you plan to spend time here. This type of exhaust fan can be used even when you aren't present in the garage to keep the air quality high for your vehicle and for everything else you have stored inside.

ventilation ducts in a garage

If you don't plan to be in your garage very often and needed an exhaust fan only occasionally, however, consider a freestanding fan. With a freestanding fan, you will need to direct the airflow out through a window or door. There will also be cords on the fan that can be hazardous if they're not secured, so pay attention to where these cords are if you're using this type of fan. The size of the fan you buy depends on the size of your garage. In a wide-open area like a garage, smaller exhaust fans won't make enough of a difference. Choose a fan that's at least 18 inches for a standard, single-car garage. You can use a mathematical formula to determine a perfect size of an exhaust fan, but it's a good rule of thumb to choose a fan that's between 18 to 24 inches in size for most garages.

What type of exhaust fan should you buy? If you have enough height in the garage and it's a single-story structure, a ceiling exhaust fan is probably your best choice. Otherwise, look for a wall unit. Before you buy and definitely before you install your fan, look outside the walls of the garage. You don't want to install your fan so that it faces your neighbor's windows, for example. Make sure you can install your fan somewhere it won't disturb anyone else, and all that hot, moist air has somewhere to go that won't cause any damage as it exits through the fan and into the atmosphere.

front of a garage with doors and vents

Installing a Garage Exhaust Fan

Once you have your fan and you've figured out where you want to put it, you can install your garage exhaust fan and start getting good air circulation right away.

Step 1 - Safety First

Before mounting and wiring your garage exhaust fan, turn off all garage circuit breakers to prevent any electrical accidents during installation.

Step 2 - Make a Hole

Once you have decided where to install your fan, you need to cut a hole where it will be fitted. Most exhaust fans come with a template, which you can use as a guide to make perfect cuts. Use a drywall saw to carefully cut the wall and remove drywall. Remove any insulation you find in the hole, because it's a fire hazard.

Step 3 - Cut the other Hole

You'll need a hole on the other side of the wall or the ceiling. This may require you to use a masonry saw or jigsaw, depending on the building materials used for your garage. Use the same template, or make your own using cardboard, to cut a hole that's the right size for your fan. Remove the masonry or wood from the area.

Step 4 - Insert a Frame

You need to insert a housing frame in the hole so you don't lose structural integrity. This is a simple square wood box. A housing frame may come with your fan, but you can also build your own using simple 2 x 4s. Simply cut the pieces to size and nail the ends together to make a square. Insert this in the hole. When possible, cut the hole between wall studs so the studs can lend their own support to the frame. Secure the frame directly to the studs or ceiling beams with nails.

Step 5 - Prep the Housing

Insert a metal clip on the fan housing to accept an electrical ground.

Step 6 - Add the Wiring

Use only manufacturer-approved wiring to connect the fan to a power source. It is highly recommended to run fan wiring to its own independent circuit breaker and not share a direct current source. Make sure to run an on/off wiring set up, even if you plan on continuous fan operation.

Plug into the nearest electrical outlet. Check that the fan's motor works. If not, there is something wrong with the wiring. Check your work using the manufacturer's instructions. You may wish to consult with an electrician for this step, particularly if you aren't comfortable with wiring.

Step 7 - Install the Blades

Now you need to install the front part of the fan, or the blades that will ultimately turn to circulate the air. This should fit in by means of screws to the back part of the fan. Use a screwdriver to secure the screws tightly.

Step 8 - Finish the Installation

Screw in the exhaust hose following the instructions. Make a hole in the roof of the garage near the exhaust pipe, and then push the exhaust hose for the fan through this opening. You will be able to secure this using the connections in the exhaust fan kit. Seal the hole around the hose with caulk.

Step 9 - Place the Fan

Now that the fan is wired and the exhaust connected, you can fit your fan onto the wall or ceiling. Screw the backing of the fan onto the ceiling studs, and then seal around the hole with caulk. Make sure that there are no holes along this seal, turn the power back onto your garage, and check the fan. The light switch will now turn on the fan.