I am planning out a major basement finishing project and would like to seek some guidance on a dryer vent question. I plan on having my dryer vent behind my framed drywall, allowing for 6" of space for the vent between the concrete wall and the framed wall. The vent is five inches. Would this be okay to do?


Vent Passage

  • What material are you planning to use for the vent? Dec 12, 2016 at 23:26
  • Sheet metal pipe I believe.
    – Elias51
    Dec 12, 2016 at 23:30
  • Consider how one would clean out the vent as I've yet to see a dryer that traps all lint before it gets to the vent line. Dec 13, 2016 at 20:15

1 Answer 1


In general it looks good but what you need to consider is the total length can not be longer than 25' and for every 90° you shall subtract 5ft from the total 25' allowed.

Here are some codes regarding such.

The recommendations outlined below reflect International Residential Code (IRC) SECTION M1502 CLOTHES DRYER EXHAUST guidelines:

M1502.5 Duct construction.

Exhaust ducts shall be constructed of minimum 0.016-inch-thick (0.4 mm) rigid metal ducts, having smooth interior surfaces, with joints running in the direction of air flow. Exhaust ducts shall not be connected with sheet-metal screws or fastening means which extend into the duct.

This means that the flexible, ribbed vents used in the past should no longer be used. They should be noted as a potential fire hazard if observed during an inspection.

M1502.6 Duct length.

The maximum length of a clothes dryer exhaust duct shall not exceed 25 feet (7,620 mm) from the dryer location to the wall or roof termination. The maximum length of the duct shall be reduced 2.5 feet (762 mm) for each 45-degree (0.8 rad) bend, and 5 feet (1,524 mm) for each 90-degree (1.6 rad) bend. The maximum length of the exhaust duct does not include the transition duct.

M1502.2 Duct termination.

Exhaust ducts shall terminate on the outside of the building or shall be in accordance with the dryer manufacturer’s installation instructions. Exhaust ducts shall terminate not less than 3 feet (914 mm) in any direction from openings into buildings. Exhaust duct terminations shall be equipped with a backdraft damper. Screens shall not be installed at the duct termination.

M1502.3 Duct size.

The diameter of the exhaust duct shall be as required by the clothes dryer’s listing and the manufacturer’s installation instructions. Look for the exhaust duct size on the data plate.

M1502.4 Transition ducts.

Transition ducts shall not be concealed within construction. Flexible transition ducts used to connect the dryer to the exhaust duct system shall be limited to single lengths not to exceed 8 feet (2438 mm), and shall be listed and labeled in accordance with UL 2158A.

  • Thanks, I reviewed that as well. I have 10 ft from end to end with two 90 degree angles for a total of 20 feet.
    – Elias51
    Dec 12, 2016 at 23:31
  • @Elias51 and as for "Exhaust ducts shall terminate not less than 3 feet (914 mm) in any direction from openings into buildings" I would assume if no other angles are needed, then you are good to go :) Dec 13, 2016 at 0:04

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