How Long Can a Dryer Vent Be?

In Minnesota, a dryer vent can be up to 35 feet long, measured from the connection behind the dryer to the outlet outside. Each elbow shortens that: subtract 5 feet for a standard 90-degree elbow and 2 feet 6 inches for a 45. The code also allows the length in your dryer's installation instructions, which may be longer or shorter.

Here's what to expect in this guide:

• The 35-foot rule in Minnesota's code, and how elbows reduce it
• When the dryer's manual allows a different length
• Where foil and plastic duct fit in
• How to measure your own vent and spot a restricted one
• What landlords and property managers should check

What Is the Maximum Dryer Vent Length in Minnesota?

Thirty-five feet, before elbows. The Minnesota Mechanical Code incorporates the 2018 International Mechanical Code, and section 504.8.4.1 of that code reads: "The maximum length of the exhaust duct shall be 35 feet (10 668 mm) from the connection to the transition duct from the dryer to the outlet terminal."

Many online answers quote the International Residential Code instead. In Minnesota, state rules replace that code's mechanical chapters with the Minnesota Mechanical Code, so the mechanical code is the one to read here. The U.S. Fire Administration (USFA) describes building codes the same way: "the total length of the vent duct not exceed 35 feet (shorter if there are turns or bends)."

Two cautions. We read the code text in November 2026, and codes are updated. A home built under an older code may not match today's text, and your local building official has the final say on any installation. We clean dryer vents; we don't enforce code.

How Much Do Elbows Shorten a Dryer Vent?

Each fitting uses up part of the 35 feet. The code says "Where fittings are used, the maximum length of the exhaust duct shall be reduced" according to its fitting table. From that table:

• 4-inch radius mitered 90-degree elbow: 5 feet
• 4-inch radius mitered 45-degree elbow: 2 feet 6 inches
• 6-inch radius smooth 90-degree elbow: 1 foot 9 inches
• 6-inch radius smooth 45-degree elbow: 1 foot

A mitered elbow is the segmented kind. A smooth elbow with a wider sweep costs less length. Two examples using the table:

• Two mitered 90-degree elbows use 10 feet, leaving 25 feet of straight duct.
• Three mitered 90-degree elbows and one 45 use 17 feet 6 inches, leaving 17 feet 6 inches.

Can a Dryer Vent Be Longer Than 35 Feet?

Yes, when the dryer's manufacturer allows it. The 35-foot table is one of the methods the code accepts. Another is the manual: "The maximum length of the exhaust duct shall be determined by the dryer manufacturer's installation instructions." The code also has a method for runs that use a listed dryer exhaust duct power ventilator, often called a booster fan.

Manuals differ, so read the one for your model. As one example, LG's venting guide says "the maximum run for the home ventilation should not exceed 65 ft." and "do not use more than four 90° elbows." Its table for 4-inch rigid metal duct runs from 65 feet with no elbows down to 28 feet with four, and less with the second wall cap type it lists. GE Appliances tells owners to "consult the Installation Instructions for your specific model for the proper length and number of turns for the vent pipe."

One useful clue: the code says that where the duct's equivalent length exceeds 35 feet, the length "shall be identified on a permanent label or tag" located within 6 feet of the exhaust duct connection. If your run is long, look for that tag near the dryer.

Does the Flexible Hose Behind the Dryer Count?

No, but it has its own limit. The connector between the dryer and the wall is called the transition duct, and the 35 feet starts where it ends. The code says transition ducts "shall be a single length that is listed and labeled in accordance with UL 2158A," must be "not greater than 8 feet (2438 mm) in length" and "shall not be concealed within construction."

Everything past that point should be metal. The code calls for exhaust ducts with "a smooth interior finish," made of metal and 4 inches in diameter.

Why Is Foil or Plastic Duct a Problem?

It kinks, crushes and holds lint. The USFA says "flexible vents can twist, allowing lint to build up and catch on fire if it comes in contact with a sufficient amount of heat." The U.S. Consumer Product Safety Commission (CPSC) says flexible plastic or foil duct "can more easily trap lint and is more susceptible to kinks or crushing, which can greatly reduce the airflow."

Both agencies point to metal. The USFA says to "replace coiled-wire foil or plastic venting with rigid, non-ribbed metal duct." The CPSC says most manufacturers specify rigid or corrugated semi-rigid metal duct, "which provides maximum airflow."

What Happens if a Dryer Vent Is Too Long?

Lint may build up faster and drying may slow down. The USFA explains: "If a dryer vent is too long or has many bends and turns, moisture in the warm air passing through it condenses on the vent surfaces, attracting lint. Eventually, the lint accumulates and creates resistance."

The signs are the same as for any restricted vent:

• Slow drying. The USFA says heavy clothes such as blue jeans or towels taking a long time to dry point to a clogged vent. See why your dryer takes two cycles to dry.
• Hot clothes. Clothes that "feel hotter than usual at the end of the cycle" are another USFA sign.
• Little or no air outside. The CPSC says to check the outside vent while the dryer runs. If exhaust air isn't escaping, "the vent or the exhaust duct may be blocked."

For a longer checklist, see our guide to dryer vent fire warning signs.

How Do You Measure Your Dryer Vent?

1. Find where the vent leaves the house: a hood on an outside wall or a cap on the roof.
2. Measure the straight sections you can see, and estimate the hidden ones from the route between the dryer and the outlet.
3. Count the elbows, including the ones at the wall behind the dryer and at the outlet.
4. Subtract the elbow allowances from 35 feet, or use the table in your dryer's manual.
5. Check the transition duct. It should be one piece, 8 feet or shorter, and not crushed behind the dryer.

If most of the run is hidden in a wall, floor or ceiling, you may not be able to measure it yourself. That is common, and it is a good reason to watch for the signs above.

What Can You Do About a Vent That Is Too Long?

Start with what you can reach. Replace a foil or plastic connector with a listed transition duct, and straighten any kinks behind the dryer. Shortening or rerouting the duct inside walls or ceilings is installation work for an HVAC or appliance installer, so ask your city's building department what applies before work starts.

A long run that can't be shortened needs regular cleaning. GE says "it is recommended that you clean the ductwork completely at least once a year." The USFA says the venting system should be cleaned periodically "by qualified service personnel, especially if it is taking longer than normal for clothes to dry."

Cleaning removes lint. It doesn't change how long or bent the run is. As part of MedCity Duct Cleaning's dryer vent cleaning, we trace the vent run from the back of the dryer to where it exits your home and check its length, the number of turns, the vent material and the exterior vent cap, so you'll know what you have.

What Should Landlords and Property Managers Check?

The parts tenants can't see. A renter sees the lint filter, not the duct in the wall. The USFA notes that laundry areas in "upstairs bedrooms, hallways, bathrooms, kitchens, and closets" may "require longer dryer vent ducts in order to reach an outside wall." If a unit's laundry is in a hallway closet or on an upper floor, expect a longer run. Between tenants, check that:

• The transition duct is a single listed piece, not foil or plastic, and isn't crushed.
• Air comes out of the outside vent when the dryer runs, and the flap opens.
• The outlet has no screen. The code says "screens shall not be installed at the duct termination."
• Residents know to report loads that take longer than normal to dry.

What Does This Mean for Rochester-Area Homes?

The Minnesota Mechanical Code is a state code, so the starting point is the same 35 feet in Rochester, Byron, Kasson, Stewartville and Pine Island. What varies is the house: where the laundry sits, how many turns the duct takes to get outside, and what the duct is made of.

Winter adds a deadline for some homes. If your dryer vents through the roof, read can you clean a rooftop dryer vent in winter. For vents on outside walls, see is snow blocking your furnace or dryer vent dangerous.

Frequently Asked Questions

How long can a dryer vent be?

In Minnesota, the mechanical code allows a dryer exhaust duct of up to 35 feet, measured from the transition duct connection behind the dryer to the outlet outside. Each elbow shortens that limit. The code also allows the length in the dryer manufacturer's installation instructions, which may be different.

How much length does a 90-degree elbow use?

A standard 4-inch radius mitered 90-degree elbow counts as 5 feet, and a 45-degree elbow counts as 2 feet 6 inches, in the Minnesota Mechanical Code's fitting table. Smooth elbows with a larger radius count for less. A run with two standard 90-degree elbows can have 25 feet of straight duct.

Can a dryer vent be longer than 35 feet?

Yes, if the dryer manufacturer's installation instructions allow it. The code lets the manufacturer's instructions set the maximum length. Check the manual for your model, because the allowed length changes with the number of elbows and differs between dryers.

Is flexible foil duct allowed for a dryer vent?

Only as a short connector, and only if it is listed for that use. The code text calls for a metal exhaust duct with a smooth interior. The transition duct between the dryer and that duct must be a single length listed to UL 2158A, no longer than 8 feet, and not concealed within construction.

Can I vent my dryer into the attic or crawl space?

No. The U.S. Fire Administration says building codes require clothes dryers to be exhausted directly to the outdoors, and venting into attics, soffits, ridge vents or crawl spaces is expressly prohibited.

How can I tell if my dryer vent is too long or restricted?

Run the dryer and check the outside vent. The CPSC says that if no exhaust air is escaping, the vent or duct may be blocked. The U.S. Fire Administration adds that heavy clothes taking a long time to dry, or clothes that feel hotter than usual at the end of the cycle, point to a clogged vent.

Have a long or slow dryer vent? Learn about dryer vent cleaning, request a free quote online or call us at (507) 289-4039.

Sources

1. Minnesota Rules, part 1346.0050: Minnesota Mechanical Code, Title; Incorporation by Reference, Minnesota Office of the Revisor of Statutes
2. Minnesota Rules, part 1309.0010: Adoption of International Residential Code by Reference, Minnesota Office of the Revisor of Statutes
3. Minnesota Mechanical Code 2020, Chapter 5 Exhaust Systems, Section 504 Clothes Dryer Exhaust, UpCodes (online copy of the code text)
4. Clothes Dryer Fires in Residential Buildings (2008-2010), TFRS Vol. 13, Issue 7, U.S. Fire Administration
5. Overheated Clothes Dryers Can Cause Fires, Publication 5022, U.S. Consumer Product Safety Commission
6. LG Dryer Proper Venting and Installation Tips, LG Electronics
7. Dryer - Taking Too Long To Dry Clothes or Not Drying at All, GE Appliances