Dryer Vent Code Guidelines

Dryers use jets of extremely heated air to dry clothes. The heat itself is a hazard and needs proper venting. To add to this, the jets also carry away flammable lint from the clothes and this instantly makes it a procedure that requires attention and proper regulation.

dryer vent expert

To regulate the proper usage of dryer vents and prevent fire outbreaks, authorities have set guidelines for dryer vents that all homeowners need to follow.

Here we’ll take you through the most important dryer vent code guidelines. Read more.

Terminate the Vent to the Outside

Building code regulations require homeowners to route dryer vents to the outside. It is recommended not to run the vent across the crawl space or attic. In exceptional cases, consider an extended exhaust pipe that leads to the outside.

If you blow hot and humid air from the dryer into the house, moisture can build up on the surfaces and cause the rampant growth of mold and mildew. It can also cause respiratory problems for you and your family.

In addition, mold on ceilings, floors, and walls can destroy furniture and reduce the value of your property.

Length of the Duct and Materials

Guidelines for clothes dryer vents require the duct to be made of straight and smooth metal with no screws. Typically, joints can impede the proper flow of air and lint.

Although most homeowners may be tempted to run a plastic pipe through a crawl space or wall, this is not advisable because the material can be crushed under the weight of the wall. Instead of screws, you can use aluminum foil to secure or connect the pipes.

Ideally, the pipe should be straight or slender, with a length of at least 25 feet if there is a bend. Also, be sure to reduce the maximum limit by 5 feet for each 90-degree bend. Similarly, you can reduce the length by 2.5 feet for a 45-degree bend.

On another note, transition ducts should be labeled in accordance with UL-2158A regulations. This marking is important because it certifies that the ducts are not a fire hazard.

Manufacturer Guidelines

It is important to check the manufacturer’s guidelines when installing a dryer vent. Most manufacturers recommend installation in open and accessible locations to facilitate cleaning and installation.

Typically, an 8-foot length is recommended for a flexible hose that connects to the dryer vent.

In addition, dryer vent systems should be separate from other systems such as air conditioning. It should also have a metal thickness of at least 4 inches in diameter and a smooth interior. However, there is an exception if the duct is horizontal.

dryervent Guidelines

Manufacturers also recommend that exhaust ducts be supported at intervals of at least 12 feet. Likewise, they should be well fastened with screws that do not protrude 1/8 inch into the interior.

Sometimes you may want a longer vent run and need to attach an electric fan to the exhaust duct. In this case, the length of the duct will depend on the manufacturer’s guidelines.

You should also provide your local building inspector with a copy of the manufacturer’s installation guidelines.

Vents Longer Than 35 feet

It is not recommended to enclose a dryer vent through the roof because cleaning can be a challenge. It can also pose a safety hazard, as you may have to climb over the roof to install or set up.

Unless you are a professional, you should always seek the opinion of an expert if you want to connect it through the roof.

35 feet longer Dryer Vents

However, there may be some exceptional circumstances where you may need an extended duct.

For instance, if the dryer vent in a multi-story building is longer than 35 feet, the duct length on the label must be at least 6 feet from the duct connection.

You can also achieve a longer duct run by setting up a duct as recommended by a manufacturer. In most cases, you will need to place a special order with the manufacturer.

Installation for Future Use

If you are building a new property and providing a space for the occupant to install a dryer, you must designate this area as “FUTURE USE”. Also, seal the exhaust vent in this area.

Be sure to install protective plates where nails and screws enter the exhaust ducts. They should be made of steel with an optical thickness of 0.062 inches. The main purpose is to prevent fires that can result from the accumulation of lint in the vent.


It is important to follow clothes dryer venting guidelines to ensure safety and comply with building code regulations. Most states, counties, or cities have specific laws that you must follow when installing a dryer vent.

If you are unsure of how to proceed, be sure to consult a professional who is familiar with the building codes in your location.

I am a cleaning enthusiast and a writer for renowned cleaners guide sites. I am the Chief Executive Officer for All-City Janitorial and All-City Duct Cleaning. This is where I write about my exploits in detail to share my experience with everyone.

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