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Are Vents Required in Garages | Building Code Explained

Ventilation is a must in any house. Extending this to include the garage would make sense considering the fact that, at the very least, there is the potential for exhaust fumes to build up in the garage. Then there are also all the other chemicals stored and tools used in these spaces.

Surprisingly, garage ventilation is not a big subject in building codes in the USA, but let’s look at what the codes do say, whether you should ventilate your garage even if you don’t have to, and how you can do it.

Garages are considered uninhabitable spaces and don’t require vents by IRC regulation, provided they are isolated from living areas and do not contain specific equipment. However, the EPA recommends ventilation in garages to keep the room safe and comfortable for human use.

IRC Doesn’t Require Vents in Garage

The International Residential Code (IRC) does not have any regulations that explicitly state that vents are required in garages, nor does it state that vents are unnecessary in garages.

What is the IRC?

The IRC is the international safety standard for residential homes. It provides information for ensuring that your home is safe for you to live in according to the applicable conditions and provides limitations and regulations to prevent hazards.

2021 International Residential Code (International Code Council Series)

Where is it Applicable?

The IRC regulates one- and two-family dwelling units, including townhouses, which are not more than three stories above grade, have a separate egress point, and their accessory buildings cannot exceed the same height. This sounds a little confusing but refers to regular residential houses and apartments in most of the United States, the U.S. Virgin Islands, the District of Columbia, Guam, and Puerto Rico.

In terms of these residences, the code (Section R101.2) is concerned with:

“… construction, alteration, movement, enlargement, replacement, repair, equipment use and occupancy, location, removal and demolition….”

Check Local Codes as Well

Whenever it comes to building codes, my advice is always this: check your local code.

The IRC is an international standard that guides local building codes by creating safety standards. However, local municipalities amend these standards to best suit the specific circumstance of the local environment and climate to ensure that your house is as safe as possible in the place that it stands.

California is an example of a state that follows the IRC in not requiring garage vents, but there are other states and areas that can have differing regulations.

California Ventilation Governed by CMC

In California, garage ventilation is not required by code, but it is recommended by the EPA, and there are many benefits to it. Air movement keeps heat levels down, making garages more comfortable. It also helps keep AC costs down for homes with attached garages. Vents improve air quality.

The International Residential Code (IRC) doesn’t regulate garage ventilation. While the IRC is applicable in California, adaptations and additions have been made to certain regulations. In this case, the California Mechanical Code (CMC) supersedes the IRC to determine statewide building ventilation standards.  

The CMC, Chapter 4: Ventilation Air, determines the general requirements for many aspects of ventilation, such as air rate, air class, and ventilation efficiency within different types of spaces, including businesses, health care facilities, and homes.

CMC Doesn’t Regulate Garage Vents

While the CMC covers a wide variety of spaces, there is no section dedicated to the ventilation of garages in residential homes. California garages, therefore, do not have any specific ventilation requirements they need to meet.

Exception to the Vent Rule

The IRC does not require a private garage to have code standard ventilation unless it qualifies for the exception stated in Section M1307.4. If your garage contains hydrogen-generating appliances or refueling systems, ventilation is needed.

In the case of an exception, you will need to ensure that the garage communicates with the outdoor environment.

You will need to install two permanent openings or vents in the garage. One must be within 12” of the ceiling, and the other within 12” of the floor. This ensures the best airflow as old air leaves through the upper vents, creating a vacuum, which results in fresh air being pulled in through the lower vents. They must be on the same external wall and have free communication with the outdoors.

Section M1307.4.1.1 states that these openings must also have:

“[A] minimum free area of 1/2 square foot per 1,000 cubic feet (1.7 m2/1000 m3) of garage volume.”

The free area will dictate the size of the openings, and your louvers or grills must be open permanently.

Why Vents Are Not a Requirement

There are a couple of reasons why ventilation is not typically necessary in a garage, as well as conditions and measures that need to be met to make this safe.

Non-Habitable Space

A habitable space is used for living, cooking, and sleeping, so a garage is not considered to be habitable. Non-habitable areas are not regulated by the same ventilation standards as habitable spaces because they are not intended for any long-term occupation by people.

Clean Attached Garage
Clean empty swept interior suburban garage.

This means that a garage does not require the same air circulation, air supply level, and air quality as your house. Non-habitable spaces do not require a specific amount of natural and/or mechanical ventilation to move sufficient cubic feet per minute of air (CFM).

Garage Required to Be Isolated From House

In order for your garage to be exempt from home ventilation standards, it must be isolated from the house.

Section M1601.6 of the IRC states that air systems or furnaces must not supply or return air from a garage if they are supplying air to living areas. This means that it should not share ventilation with the house and must have an independent HVAC system.

Even if your HVAC system runs through the garage, there must be proper separation from the residence, and there are regulations for openings and penetrations that go through the walls and ceilings that separate the garage from the house. These rules are found in Section 302.5 of the IRC:

No opening from the garage shall go directly into a sleeping room, and any other openings must have a self-latching and self-closing:

  • A solid wood door at least 1 and 3/8” (35 mm) thick.
  • A solid or honeycomb-core steel door at least 1 and 3/8” (35 mm thick).
  • Or alternatively, a 20-minute fire-rated door.

Furthermore, ducts running through the garage must be sheet steel or approved material, of at least 26 gauge (0.48 mm), and these should not open into the garage.

You should not remove any ventilation systems from a garage that is not isolated (without providing an adequate replacement), or you will likely be violating building regulations.

Garages Not Sealed off From Outside

All indoor spaces should have a degree of ventilation. Even when insulated and shielded from heat (and air) exchange with external conditions, a garage will have at least one operable garage door. Whenever this sizable door is opened, it provides good natural ventilation.

A garage is not frequently sealed in the same way as your house as they are not considered to be a space you will live in. Therefore, they have little to no insulation and have no air sealing as they are not conditioned spaces.

As an unconditioned space, a garage should have a decent level of interaction with the external environment. The lack of air sealing means that air can leave and enter the garage space, although this is unregulated and inconsistent.

Open garage door in suburban family home

Biggest Risk Accounted For: CO Alarm

The most significant risk associated with an unventilated garage is the potential carbon monoxide (CO) build-up, as it might not disperse correctly without proper ventilation.

CO emissions are associated with appliances such as dyers, water heaters, furnaces, lawn equipment, and generators, as well as cars. It is not uncommon to find these large appliances in garages. However, these appliances generally require direct venting if they pose a risk. Cars are a different story (you cannot directly vent a vehicle).

CO is colorless, odorless, and highly poisonous. This means that it is highly toxic but very difficult to detect. As it is possible for CO to be emitted by common household appliances, you can ensure your safety by installing a CO alarm.

While the code does not state that you have to install one, it does say, in Section R315.2.1, that if the garage is attached to the house and can communicate with it, the dwelling itself needs a CO alarm. This is because in such cases, there is a chance that CO could infiltrate living areas.

Carbon Monoxide Detector

This device is designed to detect abnormal levels of CO. It will warn you of the danger of remaining in your garage if there has been a build-up of CO within the unventilated room. These alarms typically last 5-7 years and are a reliable safety feature if they are kept in working order.

It is also essential to conduct proper maintenance procedures on your appliances to ensure that no components or venting are compromised.

The Environmental Protection Agency (EPA) recommends exhaust ventilation for garages if they are attached to the house. In addition, they recommend 100 CFM for ducted and 80 CFM for unducted exhaust fans as a standard for ventilation, which should be continuous.

As much as isolated garages are considered non-habitable areas, the fact remains that garages are in frequent use. For example, many people double their garage as a gym space, workshop, and laundry room.

When you put your garage to practical use, it would be wise to ensure it is ventilated. EPA even suggests fans as an alternative to an exhaust system, provided they are activated whenever the garage is occupied, as well as for at least one hour after.

My dad keeps his tools and a workbench in the garage; whenever he has something to repair, he takes it there, and I’m sure he’s not the only one. If you are going to spend any length of time in the garage and you may not be able to endure opening the door whenever you are in there (snow anyone?), then ventilation is likely a good addition to the space.

Ultimately, there are many reasons why a garage may have and benefit from vents.

Garage Vent Options

Below is a list of the available venting options for your garage, as well as the biggest pro and con associated with each.

1. Windows

DescriptionWindows are easy to install and provide natural ventilation when they are open. They also offer natural lighting and there is a variety of styles to choose from.
ProThey will create a cross breeze to circulate air in, out, and around your garage if positioned correctly.
ConDespite the season or weather, they have to be kept open to be effective.

2. Window Fans

DescriptionWindow fans are designed (with adjustable panels) to fit into a window frame. It will pull fresh air into the garage while ejecting stale air. It helps with airflow and circulation, as well as cooling down the room; a bonus since garages are known for being stuffy in summer.
ProIt is convenient, simple, and affordable to install, as you will not need to cut holes into your garage to install it if there is a window frame available to use.
ConIt can only be installed in a window frame.
Comfort Zone Twin Window Fan with Remote Control, Removable Cover, Reversible, 9 inch, 3 Speed, 3 Function, Expandable, Exhaust, Airflow 8.40 ft/sec, Ideal for Home, Kitchen, Bedroom & Office, CZ310R
  • ADJUSTABLE 3-SPEED CONTROL: Tailor the airflow and optimize air circulation in any environment with the 3-speed functionality of this twin window fan. Choose between low, medium, or high-volume air...
  • VERSATILE MULTI-FUNCTIONALITY: Select the cooling function to refresh and invigorate the room with a gentle breeze. Opt for the exhaust function to effectively remove stale air and promote better...
  • FLEXIBLE WIDTH ADJUSTMENT: The accordion expanders of this twin window fan provide adjustable width, ranging from 23-1/2" to 37", allowing it to accommodate most window sizes. Easily customize the...
  • EFFORTLESS REMOTE CONTROL: Enjoy the ultimate convenience of the included remote control, which allows you to effortlessly adjust speed settings, select fan functions, and power on/off the fan from a...
SAILFLO 10 Inch Window Shutter Exhaust Fan with Reversible Airflow, 297CFM 30W Wall-Mounted Quiet Ventilation Fan Air Intake Extractor for Bathroom Home Bedroom Attic, φ8 Inch Impeller
  • ★Reverse Exhaust: This window fan is a 2-way linkage type ventilation system, it not only puts air to the outside but also draws in air to the inside. The exhaust direction can be easily reversed...
  • ★High Performance: Exhaust Airflow 500 m³/h(297 CFM), Intake Airflow 380 m³/h(226 CFM) | Noise: 43 dBA. 30-watt low power, which makes the fan powerful and energy-saving. With a noise level of 40+...
  • ★Safe and Reliable: The fan includes an overheat protector and an efficient temperature fuse, ensuring safe usage at all times, Equipped with a high-quality, wear-resistant sleeve bearing motor,...
  • ★Wide Application: The simple yet modern look and feel will fit perfectly into any of your décor. Suitable for vents, kitchens, bathrooms, shopping malls, bedrooms, and living rooms. detachable...

Last update on 2024-05-29 / Affiliate links / Images from Amazon Product Advertising API

3. Wall Vents

DescriptionA wall vent allows fresh air into a space without allowing dust and noise in the way a window would; it is appropriate for living areas and non-habitable areas. It helps retain heat in a room during the winter, and these vents will continue to operate without your constant supervision. It will be installed near a window on an external wall.
ProIt will supply fresh air to the garage even with the windows and doors closed.
ConIt is only an intake supply and will not exhaust air from the garage, which means that it will not manage odors and fumes well enough on its own.
EZ-FLO 10 x 6 Inch (Duct Opening) White Air Vent Cover for Wall or Ceiling, Two-Way Ventilation Register, 13-3/4 Inch x 7-3/4 Inch (Overall Dimensions), Solid Steel HVAC Cover, 61610
  • WALL OR CEILING VENT: 2-way Air deflector features a duct opening measuring 10 inch x 6 inch, the overall dimension measures 11-3/4 x 7-3/4 inches **Inner grill measurements will be roughly ¼ to ½...
  • FUNCTIONALITY: 5 adjustable smooth glide dampers and 18 louvers control the amount and direction of airflow for rattle-free quiet ventilation and optimized performance for heating and cooling systems;...
  • DURABLE: Two-way air registers feature all steel construction with a heavy-duty powder-coated matte white finish to add a contemporary touch to your home decor and withstand heat and cold without...
  • ENERGY EFFICIENT: EZ-FLO air vent covers are designed for optimal airflow, increasing the efficiency of residential and commercial HVAC systems; suitable for heaters, AC, or combined systems

Last update on 2024-05-29 / Affiliate links / Images from Amazon Product Advertising API

4. Wall-Insert Fans

DescriptionWall-insert fans are similar to exhaust fans, but as they are generally installed on an external wall and vent directly outside, ducting is unnecessary.
ProThey are easy to install as they do not require ducting.
ConThere is a risk of back-drafting, which is counterproductive for ventilation.

No products found.

5. Ceiling-Insert Fans With Ducts

DescriptionThese fans are also known as exhaust fans (like the kind you would use in a bathroom). They extract warm air and moisture with the fan. The air runs through ducting (either in the roof or wall) and is ejected into the outdoors. These are easy to install and provide high-quality ventilation.
ProCapable of providing code-compliant ventilation to a room as well as exhausting odors and fumes, venting particles and dust, and dealing with humidity and temperature issues.
ConLeaking can occur if the fan or ducts are incorrectly installed or sized or if any of the components begin to wear or break.
Broan-NuTone HD80L Heavy Duty Ventilation Fan, Residential or Commercial Installation, 80 CFM, 2.5 Sones,White
  • FAN COMBO: Heavy-duty ventilation fan and light combo helps reduce odors and and is powerful enough for rooms (including bathroom) up to 75 sq. ft. at 80 CFM for your convenience
  • EFFICIENT: Bright 100-Watt incandescent light (bulb not included) provides high-quality lasting use. Housing dimensions 8"x8-1/4"x5-3/4"
  • EASY INSTALLATION: Easy to install and/or replace existing product for DIY'ers. Includes polymeric duct connectors with tapered sleeves for easy, positive ducting and integral key-holed mounting...
  • DECORATIVE: White polymeric grille with shatter-resistant light diffusing lens complements virtually any decor

Last update on 2024-05-29 / Affiliate links / Images from Amazon Product Advertising API

6. Soffit Vents

DescriptionSoffit vents can be easily installed under the eaves of your garage roof, and they will allow fresh air into the garage.  
ProThey will help create airflow in the garage by allowing fresh air to enter the space.
ConYou will need to install another ventilation device (like a fan or different vent) in the garage to make the soffit vents truly beneficial.
4 Inch Round Air Vent, HG Power 4" ABS Soffit Vent, Louver Grille Vent Cover with Mesh Screen for Living Room Ceiling Shed White - Opening Size 3.59"
  • Product Parameter: Our round air vent is designed to be compatible with standard sizes, featuring a 4" diameter. The flange opening measures 3.59 inches, and the panel size is 5.78 inches. Boasting a...
  • Built-In Screen Mesh: Experience fresh air circulating in your home without letting in unwanted debris. Our HG Power round air vent incorporates a built-in screen mesh, safeguarding your environment...
  • Premium Material: We place a premium on quality and longevity. The soffit vent is made from high-quality ABS material, rendering it water-resistant, rust-resistant, and simple to clean. You can trust...
  • Easy To Use: Our vent is intentionally designed for user-friendliness. It is compatible with 6" ducting, ventilation fans, inline duct fans, exhaust fans, and other similar devices, delivering...

Last update on 2024-05-29 / Affiliate links / Images from Amazon Product Advertising API

You can find more information on each of these options by reading How to Vent an Insulated Garage.

Sealing Garage Vents

If your garage has vents for whatever reason you would like to seal them, then there are a couple of ways you can do this, depending on the kind of vent you have in your garage.


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