For Safety, Vent Dryer Correctly

What is the proper material to use for a clothes-dryer vent pipe? That's the question asked by Lon Grossman and Joe Gagnon, hosts of "Ask the Handyman," heard each Saturday on Detroit's AM 1270.

It seems that a caller had e-mailed one of my articles to the show expounding the use of a flexible vinyl dryer vent pipe. Grossman was kind enough to invite me to clarify this matter on the show, which I did.

In my article I stated that the reader could use plastic pipe for the connector only. The dryer was located in a concrete-block walkout basement where a new hole had to be cut in the block wall for the vent. I'm glad "Ask the Handyman" caught this mistake.

Let me state now and for the future: I do not recommend the use of this highly flammable and easily damaged material. To be safe and to meet modern standards, throw away your old venting pipe and replace it with ridged metal pipe and semi-rigid flexible connectors. Limit the length of flexible pipe to a total of 8 feet and the overall total piping to 25 feet.

Do not use screws that penetrate the pipe, and make sure the joints run in the direction of the airflow.

Do not vent a dryer to an attic or a crawl space, not only because of the potential for a fire, but also because all that moisture can lead to decay damage.

Why all the fuss over vent pipe? The following information was taken from the Webpage of the Consumer Product Safety Commission:

"The U.S. Consumer Product Safety Commission estimates that in 1998, clothes dryers were associated with 15,600 fires, which resulted in 20 deaths and 370 injuries. Fires can occur when lint builds up in the dryer or in the exhaust duct. Lint can block the flow of air, cause excessive heat buildup, and result in a fire in some dryers.

"Replace plastic or foil, accordion-type ducting material with rigid or corrugated semi-rigid metal duct. Most manufacturers specify the use of a rigid or corrugated semi-rigid metal duct, which provides maximum airflow. The flexible plastic or foil type duct can more easily trap lint and is more susceptible to kinks or crushing, which can greatly reduce the airflow."

When shopping for dryer vent pipe and connectors at your local home store, you'll find flexible vinyl and flexible aluminum pipe that is rated UL 181 by Underwriters Laboratory. This type of pipe is used for heating ducts, bathroom vent fans and general purpose venting, but not for clothes dryers.

Look for the semi-rigid flexible aluminum ducting, UL 2158A, which is approved for dryers or range hoods and temperatures up to 430 degrees F. Trying to save a few dollars on vent pipe could end up costing you your home.

Dwight Barnett is a certified master inspector with the American Society of Home Inspectors.