Dryer Vent Safety
Clothes dryers use hot air and a spinning drum to remove water from wet clothing. This heat can come from either an electrical heating element or gas burner. As clothes dry, they release a significant amount of water vapor, which is expelled from the dryer and the home through an exhaust duct, commonly known as a dryer vent. However, for a dryer vent to properly exhaust moist air outside a home, it must meet certain requirements.
First, the vent must be properly connected, which is usually located behind or beneath the dryer. Additionally, the vent should not be restricted, as the flexible plastic or metal ducts can easily become crushed or kinked, reducing airflow. This can become a fire hazard as the exhaust stream carries both water vapor and lint, which is highly flammable. If lint accumulates in the exhaust duct, it can reduce the dryer’s ability to expel vapor and cause overheating, potentially leading to sparks and a fire.
According to statistics from the National Fire Protection Agency, dryer-related fires cause a significant amount of damage each year, with over 13,000 house fires, 15 deaths, and $196 million in property damage in 2005 alone. However, these fires can be easily prevented by following guidelines outlined by the International Residential Code (IRC) which state that exhaust ducts should be made of at least 0.016-inch-thick rigid metal, with smooth interior surfaces, and joints running in the direction of air flow. Additionally, the IRC states that the maximum length of a clothes dryer exhaust duct should not exceed 35 feet and any 90-degree turns in the vent reduce this 35-foot number by 5 feet. However, there are exceptions, such as if the manufacturer’s recommendations permit a longer vent, or if large radius bends are installed to reduce restrictions.
Most building code now requires a permanent label that delineates the calculated length of the dryers exhaust system. This equivalent length covers the exhaust system from the interior wall to the exterior of the structure. You can see some examples of this in these photos. Most homes don’t display this and it’s not always easy to determine if the vent runs thru the wall.
