Route the dryer vent horizontally to the home's outside wall. Duct work should pitch 1/4-inch per foot to the outside. This keeps moisture out of the pipe. For basement laundry areas where your ductwork will run vertically to the outside wall, you may need to use 90-degree elbows.
Yes, an electric dryer typically needs to be vented outside to ensure proper airflow and to prevent moisture buildup in your home. Venting outside helps to expel hot, moist air produced during the drying process, which can otherwise lead to mold growth, musty odors, and increased humidity levels indoors.
M1502.
Exhaust ducts shall terminate on the outside of the building or shall be in accordance with the dryer manufacturer's installation instructions. Exhaust ducts shall terminate not less than 3 feet in any direction from openings into buildings. Exhaust duct terminations shall be equipped with a backdraft damper.
The most common place to vent your dryer is horizontally through the exterior wall near the dryer, which is the ideal placement. Other common locations are through (but not into) the basement or the attic/roof. For most dryer models, you can't run the exhaust duct more than 25 feet from the dryer to the exhaust port.
Indoor Dryer Vent Safety Issues
Here are a few potential safety issues with indoor dryer vents: Excessive moisture can lead to mold growth and structural damage. Drywall, wood, and other building materials are not designed to withstand constant dampness. Dryer exhaust introduces pollutants into your home's air.
Per the requirements of the International Residential Code, Section M1502 (2009-2021 IRC), the clothes dryer exhaust duct should be a rigid or semi-rigid metal duct made of galvanized steel or galvanized aluminum with a smooth interior finish and a duct diameter of 4 inches.
Fire Hazards: Running a traditional dryer without a vent leads to dangerous lint buildup, increasing the risk of fires. Moisture Damage: Without proper ventilation, trapped humidity can encourage mold and mildew growth, affecting indoor air quality and structural integrity.
DO NOT terminate dryer vents in crawl spaces or attics. Dryer vents that terminate in crawl spaces or attics allow for moisture to deposit and encourage mold growth and health hazards. Dryer vents must terminate outside of the building.
In the United States, most home inspectors refer to the International Residential Code (IRC) M1502 for dryer venting. However, some states may have additional regulations. The International Mechanical Code (IMC) 504 also includes extensive clothes dryer requirements.
When installing a dryer vent for laundry centers in basement locations, the vent hood on your home's exterior must be at least 12 inches from the ground. A dryer duct should be 25 feet or less. Subtract 5 feet for each 90-degree turn and 2 1/2 feet for each 45-degree turn.
While dryers can be vented inside or outside, it is generally recommended to vent your dryer outside.
But you must bear in mind that if you are going to purchase a vented tumble dryer you need to ensure that you place the dryer near an external wall or window. This then ensures that you can have a vent fixed through the wall to allow the moisture to escape outside.
Dryer Vent Locations
The best place is usually an exterior wall, which allows the duct type to be as straight and short as possible, minimizing lint buildup and reducing the fire hazard.
Exhaust from gas dryers must be vented outside because it contains carbon monoxide.
Hot surfaces: The outside of your dryer should feel warm when it's running, but it shouldn't feel hot to the touch. The same goes for the clothing inside the dryer. Lint around outside vent: Your outside dryer vent shouldn't have lint or other debris building up around it.
In conclusion, while traditional electric dryers do require a vent to the outside to expel moist air, advancements in technology have brought ventless options to the market.
504 requires a dryer exhaust to be vented to the outside. This has been in the code for many years. There is an exception for a ventless dryer but the dryer has to be listed and labeled. Also the room where the listed and labeled dryer is installed shall have a 70 cfm exhaust fan and a floor drain.
Some places or building codes may not allow indoor dryer vents due to safety concerns, so check your local rules.
Termination. The exhaust duct should terminate outside the building at least 3 feet from any building opening, and at least 10 feet from an air conditioner or heat pump condenser (reference).
Venting a dryer vent indoors can introduce dust, lint, and other pollutants into your home's air. Laundry detergents and dryer sheets often include chemicals that are dangerous to breathe in on a consistent basis.
Dryer venting tips and practices
Flexible transition hose between the dryer and the wall outlet should be either the foil type or the aluminum flexible duct (most preferred). Do not use the plastic or vinyl. Concealed ducting must be rigid metal (galvanized or aluminum) duct.
The flexible nature and expandable configuration allow most installs to occur without any modification to the duct or the wall penetration. A pair of jumbo zip ties and you're good to go…at least for a few months until all of the internal bumps and ridges begin to clog with lint.
Designed to address the limitations of not having outdoor access for dryer venting, the vent box offers a practical indoor alternative by creating an enclosed environment. This innovative solution not only houses the dryer but also filters and manages the exhaust air, providing a controlled indoor venting system.
Dryer vent systems shall be independent of all other systems and shall convey the moisture to the outdoors. Terminations shall be a minimum of three feet from property line and 12" above the ground and not exhibit any type of screen.
Some dryer vent installations also have an external lint trap, which is also known as a secondary dryer lint trap or a 4″ In-Line Dryer Lint Trap.