Dryer Venting: Just how important is inspection and maintenance?

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5600 Fires

15 Deaths

400 Injuries

$99 Million in direct property loss


That was the average toll taken by fires caused by clothes dryers between 2002 in 2004, according to the US fire administration U.S. Fire Administration (USFA).

While clothes dryers are common, little focus is place on managing their risks.

Improper installation or maintenance of this appliance can pose a serious fire risk and dangers of carbon monoxide poisoning.

The leading factor contributing to dryer misadventures is the simple failure to clean lint from traps, vents and areas surrounding the dryer.

As recommended by the Chimney Safety Institute of America (CSIA), annual dryer vent cleaning should be part of a home or multi-dwelling unit’s annual maintenance list. This guide covers the proper selection, installation, and maintenance of vents for clothes dryers.


A typical 12-pound load of washed laundry weighs about 20 pounds. This means a dryer needs to dispose of about a gallon of water with every load. A dryer vent removes this moisture as well as heat and lint produced by the clothes dryer to the exterior of a dwelling.

Lint, a highly flammable fiber that ignites easily, forms as a dryer forces hot air through a rotating drum and the heat removes water from the clothes. While most moisture and heat vent to the outside, the easy to access and clean lint filter traps most lint before it reaches the vent.

However, some lint will always get by the initial filter. When trapped in the vent, lint will reduce venting capacity which can eventually lead to a total blockage. It can also reduce the efficiency of the dryer and result in a buildup of excess heat, moisture and lint into your home.

Thus, it is important to educate owners and renters to clean their dryer lint filter before and after every load.


Several types of ducting material are available for venting clothes dryers. CSIA recommends materials made of either rigid aluminum or galvanized steel duct. The use of flexible metal ducting may be an acceptable alternative to rigid metal duct in certain situations

Flexible thin foil and flexible plastic accordion style vents sold in home improvement stores are not unacceptable materials for venting a dryer. These vents can snag lint and allow it to accumulate and catch fire if exposed to sufficient heat.

proper venting

The best venting arrangement is to exhaust directly outdoors in the straightest, shortest distance possible.

Unfortunately, trends in new construction now placed the dryer in convenient but nontraditional areas of a home such as upstairs laundry room, hallways and bathrooms. These installations generally require longer vent lengths to reach the outside and involve sharp turns and bends to navigate the structure.

The International Building Code (IRC) and Underwriter Laboratories (UL) limit the length of a dryer vent to a maximum of 25 feet. Every 45° bend in the vent reduces the total allowable length by 2 1/2 feet and every 90° been reduces the allowable length by 5 feet.

However, some dryers may have rated lengths that exceed those established by the standard so it is best to check the manual for each dryer to determine the maximum allowable length of the dryer vent. There are also maximum allowable height requirements set by the manufactures for each model.

Dryer vents must be independent of all other systems and terminate outdoors. Never vent a dryer into another vent or chimney, the attic, a wall or a crawlspace. On the outside, install a vent hood that is equipped with a back draft damper.

proper dryer maintenance

When completed regularly, a few simple, inexpensive measures can help detect a problem with a dryer vent before it becomes a fire hazard and may even reduce wear on the dryer and energy cost to operate the dryer.

1. Remove lint from the lint filter before or after each load. Inspect the filter for rips before placing it back in the dryer

2. Wash the lint filter with soap and water every couple of months to reduce the waxy residue left behind by dryer sheets.

3. Inspect and clean outside wall dampers on an annual basis. Disconnect, clean and inspect the dryer duct and venting at least every two years. In homes with higher use or long event runs. This should occur every year. You can hire a professional to complete this service who is a Certified Dryer Vent Specialist (Found through CSIA).


  • Replace plastic and metal foil vents with 4” minimum diameter rigid metal vents.

  • Vent dryers directly to the outside in the shortest, straightest distance possible.

  • Insulate the dryer vent to protect it from lower outside temperatures.

  • Remind residents to clean the lint filter before or after drying every load and to read and follow the dryer manufacturer’s operating guidelines and suggested maintenance practices.

  • Hire a professional to inspect the dryer vent termination point at least annually for blockages, bird nests or the presence of other wildlife.

  • Never turn on a dryer and then leave the house.

  • Purchase and install a portable fire extinguisher in an accessible area near the laundry room.

Signs of a block to dryer vent:

  • Lengthy drying times

  • Clothes are hotter than normal at the end of the dry cycle

  • Dryer deactivation due to high temperatures

  • Increased heat and humidity in the area of the dryer

  • Flappers on vent hoods do not open when dryer is on

Contact our CSIA certified experts right away if you spot any of these red flags!

We service the Greater Los Angeles Area and beyond to keep your home and neighborhood safe.

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