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Community and Q&A

Dryer venting inside

Jeremy Marin | Posted in Building Code Questions on

I’m well aware of the problems venting dryers, even electric, indoors. I also know that the ICC debated whether to amend the code, making the practice against code (403.5). What I do not know is whether the amendment passed.

I help run a volunteer weatherization group and have seen only one dryer vented indoors but since then have heard of many more. It would be very helpful to tell people in addition to the moisture problems they’re creating that it is against code, if that is accurate.

Thanks in advance.

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  1. Christopher Briley | | #1

    From IRC 2009 second printing (you are interested in M1502.3)


    M1502.1 General. Clothes dryers shall be exhausted in accordance with the manufacturer's instructions.

    M1502.2 Independent exhaust systems. Dryer exhaust systems shall be independent of all other systems and shall convey the moisture to the outdoors.

    Exception: This section shall not apply to listed and labeled condensing (ductless) clothes dryers.

    M1502.3 Duct termination. Exhaust ducts shall terminate on the outside of the building. Exhaust duct terminations shall be in accordance with the dryer manufacturer's installation instructions. If the manufacturer's instructions do not specify a termination location, the exhaust duct 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.

    M1502.4.4 Duct length. The maximum allowable exhaust duct length shall be determined by one of the methods specified in Section M1502.4.4.1 or M1502.4.4.2.

    M1502.4.5 Length identification. Where the exhaust duct is concealed within the building construction, the equivalent length of the exhaust duct shall be identified on a permanent label or tag. The label or tag shall be located within 6 feet (1829 mm) of the exhaust duct connection.

    M1502.4.6 Exhaust duct required. Where space for a clothes dryer is provided, an exhaust duct system shall be installed. Where the clothes dryer is not installed at the time of occupancy the exhaust duct shall be capped or plugged in the space in which it originates and identified and marked "future use."

    Exception: Where a listed condensing clothes dryer is installed prior to occupancy of the structure.

  2. Jeremy Marin | | #2

    This is great and, hopefully, very helpful in persuading people to vent outside. Thank you very much.

  3. Riversong | | #3


    Are you saying that a thorough explanation of the health and safety threats of indoor dryer venting are not as convincing as a code mandate?

    I always rely on a science-based explanation and then add "and by the way, the building code requires it."

  4. Jeremy Marin | | #4

    That's precisely what I'm saying. Some people understood when I told them about the risks, both health and structural, of venting a dryer indoors. Others poo-pooed it.

    I have no idea how they'll respond to being confronted with the ICC but I'm hoping that these people feel the ICC carries more weight and value than my thoughts and statements. I don't care who they listen to or what convinces them as long as they fix it. I consider having the code as another piece in the arsenal.

  5. Riversong | | #5

    The ICC is the commercial code. Christopher quoted the IRC which is the residential code. Make sure you're citing the appropriate code.

  6. Jeremy Marin | | #6

    Many thanks - I'll make sure to cite the residential rather than commercial code.

  7. John Klingel | | #7

    I am just a DIY guy, but there is no way on God's earth I would vent a dryer to the inside, unless you could somehow (magically?) filter out all the crap that comes off of our varied synthetic clothing when it gets hot. I suppose you could somehow trap the lint and the moisture, but the gasses? Man, don't invite me to spend any time in a place like that. It's just downright spooky. j

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