Dryer Vent Safety – House Inspections Issues
Most of the fires caused by dryers occur in residences and are the result of improper installation, lint cleanup and maintenance. When installing a dryer vent instruction from the International Residential Code, manufacturer’s specifications, and local codes should be followed.
It is recommended that dryer vents to be inspected and cleaned by a professional annually.
During the last two inspections performed in Rochester Hills Michigan, the house inspector, found dryer vents not properly vented.
||This dryer vent on a property in Rochester Hills 48307, became detached from the roof vent.
||The dryer vent on the picture found on a different property in Rochester MI 48309, was vented close to a roof vent. In the image can be seen damage to the roof sheeting, and after a closer look in the rest of the attic space, the house inspector found signs of microbiological growth. This vent must be properly vented, and test for potential mold growth are necessary.
Clothes dryers evaporate the water from wet clothing by blowing hot air past them while they tumble inside a spinning drum. Heat is provided by an electrical heating element or gas burner. Some heavy garment loads can contain more than a gallon of water which, during the drying process, will become airborne water vapor and leave the dryer and home through an exhaust duct (more commonly known as a dryer vent).
A vent that exhausts moist air to the home exterior has some requirements:
- It should be connected. The connection is usually behind the dryer but may be beneath it. Look carefully to make sure it’s actually connected!
- It should not be restricted. Dryer vents are often made from flexible plastic or metal duct, which may be easily kinked or crushed where they exit the dryer and enter the wall or floor. This is often a problem since dryers tend to be tucked away into small areas with little room to work. Vent hardware is available which is designed to turn 90° in a limited space without restricting the flow of exhaust air. Restrictions should be noted in the house inspector’s report. Airflow restrictions are a potential fire hazard!
- One of the reasons that restrictions are a potential fire hazard is that, along with water vapor evaporated out of wet clothes, the exhaust stream carries lint – highly flammable particles of clothing made of cotton and polyester. Lint can accumulate in an exhaust duct, reducing the dryer’s ability to expel heated water vapor, which then accumulates as heat energy within the machine. As the dryer overheats, mechanical failures can trigger sparks, which can cause lint trapped in the dryer vent to burst into flames. This condition can cause the whole house to burst into flames! Fires generally originate within the dryer but spread by escaping through the ventilation duct, incinerating trapped lint, and following its path into the building wall.
In general, a house inspector will not know specific manufacturer’s recommendations or local applicable codes and will not be able to confirm the dryer vent’s compliance to them, but will be able to point out issues that may need to be corrected.