Laundry rooms and garages are often located near each other, so it may seem like a valid option to steer the dryer vents to the garage rather than outside. After all, it will require less drilling through the house, and no one lives in the garage.
However, there are several very good reasons why this is not actually a good idea, starting with the fact that it is a building code violation.
Venting a dryer into a garage is not safe. The lint, moisture, and fumes can be harmful to human health, increase the risk of fires, and damage the garage and home. In addition to being unsafe, venting a dryer into a garage can have negative consequences on the value of the home.
Building Codes Prohibit Venting Dryers Into Garages
Though garages are not explicitly specified, Section M1502.3 states that exhaust ducts must lead outside the building and be more than 3 feet from any openings into buildings.
This means venting a dryer to the garage would go against the IRC. The IRC exists to ensure safe and stable construction. If you go against building codes, you’ll be subject to fines and a reversal and redo of the project (which will be more expensive than just correctly venting the dryer in the first place).
The reason the IRC requires duct termination outside of a building is to protect people from harmful exhaust byproducts, such as carbon monoxide fumes, which are hazardous to human health.
Gas Dryers, Garages, and Carbon Monoxide
Gas dryers produce carbon monoxide through combustion and, therefore, must be vented out of the house. If you have an electric dryer, it still needs to be vented outdoors so that hot moist air and lint aren’t being vented into your home.
Carbon monoxide exposure can cause headaches, dizziness, vomiting, and chest pain. At high levels, one can pass out or die from carbon monoxide inhalation, so venting a gas dryer into the garage can be very dangerous.
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If you have an insulated garage, the risks of carbon monoxide poisoning are even higher as the harmful gas can’t escape as easily to the outdoors.
Even though the garage sees more outside air than the inside of the home, it’s still a closed-off space that will trap carbon monoxide where humans are frequently present.
There’s also already carbon monoxide present in the garage from car exhaust, increasing the danger of adding dryer exhaust to the garage.
Moisture Causes Structural Damage
Dryer vents contain moisture from the wet clothes in the dryer, which can cause issues if vented into a garage. This is especially true when garages aren’t well-finished and the surfaces aren’t protected against moisture.
Wood in the garage, such as floor joists and support beams, will rot and weaken when exposed to moisture. They would then need replacing in order to keep the garage structurally sound. Additionally, water can damage concrete by creating or widening small cracks.
These materials weakening will compromise the structure of the garage, causing safety concerns and creating expensive work that needs to be done sooner rather than later.
Garages Can Get Hot and Lint Is Flammable
Another concern with venting a dryer into a garage is the flammability of lint. The tiny fabric particles are a highly flammable dryer byproduct. This is because of both the material and their greater surface area compared with clothes themselves.
Without air conditioning or wind, garages can get quite hot when it’s warm and sunny. The high heat paired with dryer lint’s combustibility creates a recipe for disaster.
Dryer lint could ignite and cause a greater fire, especially with common garage materials that are present like brush, gasoline, and general clutter. What’s more dangerous, garage fires typically go unnoticed longer than house fires because they’re less frequented and fire alarms aren’t present.
Lint Can Get Into Cars and Other Machines
As with garages getting hot, flammable dryer lint is also problematic because it can get into cars and other machines (e.g., mowers) present in the garage.
While it may not cause an immediate fire, when the car or other machine is turned on the lint can ignite and start a fire or combustion that is immediately harmful to the person operating the machine. This is a greater worry for machines that stay in the garage unused for a while because lint will accumulate.
This combustion may also damage the car or machine by creating heat (in a different part of the machine than the engine) that could ignite or melt parts.
As seen lint’s presence in a garage can be costly financially and for human health.
Exposed Wiring in Unfinished Garages
Unfinished garages may have exposed electrical wires, which can be dangerous even without the addition of a dryer venting into the garage. Exposed wiring transmits electrical current, which can cause electric shocks or fires.
Again, flint from the dryer could ignite, this time from the electrical current passing through the wiring in an unfinished garage.
However, more likely the issue here lies with moisture from the dryer. If exposed wiring gets wet, the circuit’s current can increase and blow a fuse (short-circuiting any attached appliance).
If the wires aren’t connected to a fuse, the wire can overheat and start a fire independently.
Mold and Mildew Can Grow
Increasing the moisture content in the garage by terminating the dryer exhaust there can cause mold and mildew to form.
The garage is already an excellent breeding ground for mold and mildew as it’s dark and humid (from rain and standing water) with an absence of good airflow from windows or air vents. People sometimes have to use dehumidifiers (amazon link) in garages to reduce the moisture and prevent mold buildup.
Therefore, venting a dryer into the garage will exacerbate these issues and can cause uncomfortable symptoms (stuffy nose, itchy eyes, skin rashes, etc.) in people sensitive to mold.
As shown, it’s not a safe practice to vent a dryer into the garage. In addition, there can be some other undesirable side-effects that cause damage and decrease your property value.
Rusting Car Paint
Dryer vent moisture may increase the rusting process of metal things in your garage, notably car paint. It will create a blistering or bubbling texture in the paint and can also turn the metal on your car orange if it penetrates deep enough.
Surface-level car paint rust can be fixed by removing the blistered paint and repainting it, but to avoid this altogether you should not vent a dryer into the garage.
Wild animals like make garages their homes as protection against the elements and predators. They’re also able to find food in garage trash bins.
Neighborhood critters such as rodents are also attracted to heat and humidity, two byproducts found in dryer venting. They can cause damage by chewing electrical wires, leaving feces and urine in the garage, and entering and damaging car parts.
Difficulty in Selling Your House
When a house violates the building code, it will be difficult to sell as it won’t pass inspection. In the case of venting a dryer to the garage, it will have to be re-vented to the outdoors before it’s fit to sell to new homeowners.
Any damage to the home (as discussed above) caused by venting the dryer to the garage will also have to be resolved and may affect the selling price of the home.
Home insurance covers a certain level of risk that your home is exposed to. If you vent a dryer to the garage (breaking IRC regulations, increasing safety risks, and decreasing home value) your coverage could be voided.
Normally, informing your insurance company would adjust the coverage; however, since it’s against building code, the insurance company will not want to cover the dryer vent to the garage project.