I recently re-stained my wood patio furniture inside my garage. Even with the garage door open, the fumes were overpowering. After only a few minutes, I had to walk outside to get some fresh air.
It immediately got me thinking about whether I needed additional ventilation in my garage.
Here’s what I found out.
Residential garages are not required to have ventilation under ANSI/ASHRAE Standard 62.2. However, the EPA does recommend using an exhaust fan or roof vent to help get rid of toxic fumes and carbon monoxide. Proper ventilation can also help with airflow and heating\cooling your garage.
So even though it’s not legally required, it’s still a good idea to have extra ventilation in your garage.
Let’s look at why you’d want to ventilate your garage and then discuss some solutions.
Residential Garage Ventilation Requirements
As of the time of writing, ANSI/ASHRAE Standard 62.2 is the national consensus standard on residential ventilation in the United States.
ANSI/ASHRAE does not require residential garages to be actively ventilated.
However, the EPA (Environmental Protection Agency) does recommend that residential attached and builtin garages use either a 100 cfm (ducted) or 80 cfm (un-ducted) fan to vent any toxic fumes directly to the outside. (pdf source)
5 Reasons Why Your Garage Needs Ventilation
Even if ventilation isn’t legally required for your residential garage, here are five reasons you may want to invest in a ventilation system anyway.
There’s a lot of nasty stuff in your garage: weed killers, pool chemicals, paint, or harsh cleaning supplies. However, gasoline is the most common chemical you’ll smell in your garage.
They all create toxic fumes that can build up to a dangerous level inside the garage. Worse yet, they could seep from your garage into other parts of your home.
Actively ventilating your garage can help fumes dissipate, keeping them away from your family and pets.
Carbon monoxide is a toxic gas, but it’s so important it deserves its own section.
If you think about it, we store our cars, motorcycles, and gas-powered lawn equipment in garages.
Most of us will let our cars warm up in the garage on chilly mornings before we drive away. Other times, we’ll start the car to avoid draining the battery while we clean it or listen to the radio
Whenever your car’s engine is running, the exhaust gases contain carbon monoxide.
In an unventilated garage, this can be very dangerous. Carbon monoxide in the air can leak into the home or even become lethal in large amounts.
While it’s no substitute for a good carbon monoxide detector, a well-ventilated garage can help prevent carbon monoxide from building up to lethal levels.
With only a single door and usually no windows, it can be tough to get fresh air flowing in and out of your garage. No circulation means the air inside your garage can quickly get stale.
The ASHRAE 62.2 recommends that the air in residential homes be circulated equivalent to 7.5 cfm per person plus 1 cfm per 100 square feet.
While this is for dedicated living spaces and not garages, it’s still important to have fresh air circulating in any room where you spend an extended amount of time. It’s especially important if you’re planning on having a dog kennel set up in your garage.
Better Cooling in the Summer
Most garages have little or no insulation, allowing hot air to build up inside. This means garages can become stifling in warm months and frigid during the winter.
While a portable air conditioner in your garage may eventually be the answer, the first step should be to look at some form of active ventilation.
Similar to increasing airflow, adding ventilation to a garage can allow some of that built-up hot air to escape.
If you live in a warm, humid environment, adding a ventilation system to your garage or workshop can significantly reduce the amount of moisture in the air and make it easier to work in.
If your dryer vents into your garage, it’s crucial to add ventilation, so the humid air doesn’t start to corrode your tools and electronics.
Ventilation helps keep humidity levels low, protecting your tools and materials from rust, mold, and other damaging effects of too much moisture.
Why Your Garage Might Not Need Ventilation
However, not every garage needs ventilation. Usually, it depends on how you use your garage and how much time you spend in it.
If you own a detached garage separate from your home, it may not require ventilation. There’s less concern about toxic fumes or carbon monoxide with detached garages because there’s no way for the fumes to get to living areas.
You’ll still see benefits from increased airflow and cooling, however.
However, if you’re not using your garage for anything other than storage, you don’t need to ventilate it.
You may even have an empty garage that you’re figuring out what to do with.
In either case, if a garage isn’t in use, it doesn’t need to be ventilated.
Types of Garage Ventilation
Some types of garage ventilation are obviously going to be better than others.
Let’s take a look at some of the means of ventilating garages.
Simply opening your garage door will ventilate your garage as long as you use a garage fan to help circulate fresh air.
The challenge is that you’ll usually need to have another type of ventilation as well. An open garage door will let insects, animals, leaves, and other debris into your garage. It’ll also negate any kind of active heating or cooling used in your garage.
While there’s some debate on whether garages should have windows, they’re a great way to keep it ventilated.
As an added bonus, you can install a small window fan to pull fresh air in from the outside or flip it around to help clear any toxic fumes out of your garage.
Exhaust Fans and Roof Vents
Roof vents and exhaust fans often go hand in hand and are some of the best ways to actively ventilate your garage.
Exhaust fans are installed through the ceiling or outside wall to actively vent air out of your garage. Hoses or ductwork inside your garage connect to the exhaust fan, and the exhaust fan works to pull air from the garage, through the hose, and to the outside.
Roof vents are similar and can be powered or non-powered.
Installation is more challenging, however. The maximum size of the roof vent depends on the square footage of the garage’s attic (if any), the roof’s slope, and if the attic has vapor cooling.
Garage roof vents are rated by their “net free area,” or NFA. Experts recommend installing one square foot of NFA per 300 square feet of attic space if a garage’s attic has vapor cooling.
If there’s no vapor cooling in the attic, installing one square foot of NFA per 150 square feet of attic space is recommended.
Check out my ultimate buyer’s guide article if you’re shopping for a garage fan. It’s full of everything you need to know to get the best garage fan without spending a fortune!
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