Garage ventilation is necessary to prevent the buildup of potentially harmful gases, such as carbon monoxide, and to maintain a safe and healthy environment for occupants and stored items.
So how to ventilate a garage?
A garage can be ventilated by using wall vents, door vents, exhaust fans, or using air conditioning. These types of ventilations are apt for garages without windows.
They can also be used with windows to further increase airflow. Having vents and fans in place will ensure ample air movement through the garage thus preventing it from being stuffy.
There are two methods of garage ventilation; active and passive. Wall vents and door vents are passive ventilation methods as they do not require any power to run. On the other hand, exhaust fans and air conditioning are active ventilation systems, and they require power.
A garage should be kept ventilated in the winter as well.
The garage vents should be kept open in the winter allowing air to flow in and out of the garage. This will allow the moisture trapped inside the garage to escape without condensing on garage doors and vents.
Without further ado, let’s jump into the most popular garage ventilation options. Whether your garage is an attached one or a detached one these ventilation methods are good enough to keep it bearable.
1. Wall vents
Wall vents are installed in the walls of a garage to allow for the exchange of air between the interior and exterior spaces.
Having a wall vent means that the hot and humid air in your garage has a way out, passively. But make sure that you install intake vents as well. The basic rule of ventilation is having both intake and exhaust vents to maximize airflow. Having no intake vents means that there is no way for fresh air to enter the garage, and so the existing polluted air in it will stay.
So you need to have at least two wall vents. The best places to install them are, one wall vent installed at the bottom part of one side of the garage and another vent installed on the top part of another side. The bottom vent lets cool air into the garage which rises as it gets hot. This hot air is vented through the vent at the top. This setup makes maximum use of cross ventilation and convection thus resulting in better ventilation.
You can also use exhaust fans in conjunction with garage vents to increase airflow. In this case, you can avoid having the exhaust vent.
Pros
- Natural ventilation without the expense of any energy
- Easy to install
Cons
- You will have to cut through the wall insulation to install these
- Not winter-proof
2. Garage door vents
To be honest, drilling through the garage wall and installing vents there is a messy job. A simpler option is to install vents on your garage door. This is a passive ventilation method, and if you are a DIYer this might be a better option for you.
Garage door vents are installed on the top and bottom sides of the garage, usually to the sides. The vent at the bottom acts as the intake vent which lets in cooler outside air. The hot air rises and exits through the vent on the top part of the garage door.
One drawback of this setup is that it is not suitable for large garage spaces. The problem is that the path of the airflow here is between the vents at the bottom and the top of the door so it will fail to circulate air throughout the space if the garage is too big.
But if you have an intake wall vent at some other part of the garage, then this will provide enough cross ventilation to cool the whole garage area.
Here is a quick video of the garage door vent installation;
Pros
- Easy to install
- Cheaper compared to other options
Cons
- Installation can damage the garage door if not done carefully
- Not good enough to vent large garages
3. Exhaust fans
Exhaust fans are a powerful option to ventilate a garage effectively. There are mainly two types of exhaust fans for garages, they are; wall-mounted fans and roof-mounted fans aka attic fans. These fans forcefully remove the air from the garage, and hence they are called active ventilation systems.
Wall mounted exhaust fans
A wall-mounted exhaust fan is installed in any outside-facing walls of the garage.
To install a wall mounted exhaust fan, first a hole the size of the exhaust ducting should be drilled on the wall of the garage. Then the fan is mounted on the inner side of the wall full with electrical connections, then the connecting duct is passed through the hole just drilled to the outside. A cover is mounted on the other side of the duct to keep water, insects, and such from entering the duct. I know my description is as vague as possible so here is a video of this;
Roof mounted exhaust fans
Roof-mounted exhaust fans are installed on the roof. They are a good choice if your garage has an open rafter ceiling. These fans are installed either on the roof or on the gable. These are basically attic fans, though installed without attics.
Even if the garage has a ceiling, QuietCool, a company that makes exhaust fans, has a model that can be installed on the ceiling. It works just like a whole house fan but is made for garages.
Whether roof-mounted or wall-mounted, for the exhaust fans to work the garage should have enough intake ventilation. For this, some vents should be installed in the garage wall.
Pros
- Powerful ventilation
- Suitable for large areas
Cons
- Ventilation requires energy
- Lack of intake vents will build up negative pressure in the garage space
4. Air conditioning
Whoa, it is against the building codes to install HVAC in a garage. First of all, it is totally a waste of energy, and then it pollutes the air inside the living areas.
But if you really want to condition your garage, you can use a split air conditioner. Using an AC unit that is not part of the home system is allowed by the building code.
There are many reasons you may want to condition your garage. Many people use their garages as DIY workshops, and it is the favorite place of many popular YouTubers. So conditioning a garage, in that case, makes sense. So, as I said before using a split air conditioner is the best way to condition a garage. This will make sure that the hot air will be exhausted directly to the outside without anything meddling with the main HVAC system of the house.
Here is a table showing the recommended size of the AC unit required for a garage based on the floor area;
| Sq.ft area of a garage | Required BTU/hour capacity of ac |
|---|---|
| 264 | 6000 |
| 360 | 9000 |
| 484 | 12000 |
| 704 | 15000 |
| 988 | 18000 |
| 1200 | 36000 |
Pros
- Conditioned, comfortable air throughout the year
- Easy to control the temperature
Cons
- Energy expenses
- Not recommended for garages that are actually used as garages
5. Windows
Not all garages have windows but having them is a good way to ensure proper air circulation throughout the garage. But not having windows is enough, they should be kept open, trust me, I know people who don’t. The placement of the windows should be so that it provides cross ventilation.
In many cases having just one window won’t do the trick as there is no separate space for the air to exit. If the garage is attached to the house it is often not possible to have windows on its two sides. One thing you can do in this case is to install a vent on the garage door. Having a garage door vent guarantees that the intaken air is exhausted resulting in a continuous cycle of intake and exhaust thus ventilating the garage of all smells and smoke. When doing this, make sure that the size of the exhaust matches that of the window. If the exhaust area is too small it will obstruct the free, natural flow of air thereby slowing down the ventilation.
Benefits of having windows
- Cools the garage fast
- Natural ventilation at zero expense on energy
Cons
- Can let in insects and rodents into the garage
- Not a good choice if you live in a cold climate zone
Is it necessary to ventilate a garage?
By the building code, it is not necessary to ventilate a garage. However, EPA (Environmental Protection Agency) recommends that garages be ventilated (source).
If you don’t want to ventilate your garage, that is totally fine. Then why would anybody want to do it?
The main benefit of garage ventilation is that it cools down the space to a bearable temperature. During summer days garages can get really hot, which is bad for your cars and many things that you store there. So while it is totally unnecessary to air condition that space, it is highly recommended that you let the hot air out. Keeping the air trapped will make the garage smell of chemicals and exhaust fumes.
Another good reason to ventilate a garage is the dangerous exhaust fumes from the vehicles you keep there. Running a car in a closed garage is a high risk of dying from carbon monoxide poisoning. According to NCOAA (National Carbon Monoxide Awareness Association), 1200 people die every year from carbon monoxide poisoning.
Active or passive ventilation: Which is better
Garages are not required to be ventilated as per the building code. Having a perfectly ventilated garage won’t increase the value of your home either. So the decision to ventilate a garage is made solely on the other benefits mentioned before. So I always recommend passive ventilation for garages, even in cases where they are inadequate.
Active ventilation is only required if you spend a lot of time in the garage. Then it is necessary to make the space comfortable. EPA recommends using exhaust fans of size either 100 CFM (for ducted fans) or 80 CFM (un-ducted) which run throughout the time. You don’t actually require a fan that generates thousands of CFM in most cases.
The main benefit of passive ventilation is that it doesn’t require any sort of supervision. Once you drill a vent you are done. On the other hand, an exhaust fan will require some sort of supervision however minimal it is. Vents and windows do not require energy either whereas exhaust fans require energy, and the wiring can be a messy job.
