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    dryer vent

    dryer vent

    New postby mtCDCcb on Fri Aug 26, 2011 3:30 pm

    I live in a 3 unit stacked condo complex. We recently found out that our dryers were venting directly into our crawlspace. Needless to say this was causing a moisture problem. We had it vented to the outside but I noticed that the contractor didn't use solid piping for the work. Is piping required by the IBC? If so can you provide a reference? Thanks.
    Seems to me this could be a fire hazard as built.
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    Re: dryer vent

    New postby Jerry Peck - Codeman on Sat Aug 27, 2011 10:55 am

    Are the clothes dryer exhaust ducts vented separately or together into a common exhaust duct or are they each vented separately all the way down?

    Are the exhaust ducts run in the same chase or each run separately in their own chase?

    mtCDCcb wrote:Seems to me this could be a fire hazard as built.


    That would be correct if the exhaust ducts not run as required and not constructed from the proper material, all of which is based (to some extent) on where and how they are routed.

    If the dryer exhaust ducts are routed through a common shaft, most likely the minimum thickness of the ducts would be 26 gage steel and they would need to be in a 2 hour rated shaft. If the dryer exhaust ducts never leave the condo unit from which they originate, most likely the minimum thickness would be 30 gage, and no rated shaft would be required.

    Regardless, though, they are NOT allowed to exhaust into the crawlspace.
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    Re: dryer vent

    New postby mtCDCcb on Wed Sep 07, 2011 2:21 pm

    They are all vented in one duct. It used to exhaust into the crawlspace but we routed out of the crawlspace to the exterior of the building. The part added to exhaust it out of the crawlspace was semi rigid clothes dryer transition ducting. Is there a code reference in the 2006 I-codes that I can reference to the contractor? Thanks.
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    Re: dryer vent

    New postby Jerry Peck - Codeman on Wed Sep 07, 2011 6:08 pm

    mtCDCcb wrote:They are all vented in one duct.


    That would be the riser duct, it should be in a fire-rated shaft as it goes, I presume, from floor to floor.

    It used to exhaust into the crawlspace ...


    That was not good, exhausting into the crawlspace was never allowed by the codes.

    ... but we routed out of the crawlspace to the exterior of the building.


    Which is where it should have been routed to originally.

    The part added to exhaust it out of the crawlspace was semi rigid clothes dryer transition ducting.


    That is not allowed for that use, that duct needs to be minimum 26 gage galvanized sheet metal.

    Is there a code reference in the 2006 I-codes that I can reference to the contractor? Thanks.


    For which part, exhausting to the exterior, not using that flexible transition duct, or ... ?
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    Re: dryer vent

    New postby mtCDCcb on Fri Sep 09, 2011 5:12 pm

    The code reference for the requirement for the ducting material.

    THe contractor is not who originally vented the dryers. We noticed that they vented into the crawlspance and had for 20+years and that this wasn't good and hired someone to vent them to the outside. Upon review we thought the material used was a fire hazard and wanted to double check the requirement for the ducting material. I do know that the governing codes in our community is the 2006 icodes. Thank you.
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    Re: dryer vent

    New postby Jerry Peck - Codeman on Fri Sep 09, 2011 8:40 pm

    mtCDCcb wrote:The code reference for the requirement for the ducting material.


    There are too many unknowns to give you a precise and exact answer, but here is one section typical of those sections which may likely be applicable: (bold and underlining are mine)
    - 716.6 Horizontal assemblies. Penetrations by ducts and air transfer openings of a floor, floor/ceiling assembly or the ceiling membrane of a roof/ceiling assembly shall be protected by a shaft enclosure that complies with Section 707 or shall comply with Sections 716.6.1 through 716.6.3.
    - - 716.6.1 Through penetrations. In occupancies other than Groups I-2 and I-3, a duct constructed of approved materials in accordance with the International Mechanical Code that penetrates a fire-resistance-rated floor/ceiling assembly that connects not more than two stories is permitted without shaft enclosure protection, provided a listed fire damper is installed at the floor line or the duct is protected in accordance with Section 712.4. For air transfer openings, see Exception 7 to Section 707.2.
    - - - Exception: A duct is permitted to penetrate three floors or less without a fire damper at each floor, provided it meets all of the following requirements:
    - - - - 1. The duct shall be contained and located within the cavity of a wall and shall be constructed of steel not less than 0.019 inch (0.48 mm) (26 gage) in thickness.
    - - - - 2. The duct shall open into only one dwelling or sleeping unit and the duct system shall be continuous from the unit to the exterior of the building.
    - - - - 3. The duct shall not exceed 4-inch (102 mm) nominal diameter and the total area of such ducts shall not exceed 100 square inches (0.065 m2) in any 100 square feet (9.3 m2) of floor area.
    - - - - 4. The annular space around the duct is protected with materials that prevent the passage of flame and hot gases sufficient to ignite cotton waste where subjected to ASTM E 119 time-temperature conditions under a minimum positive pressure differential of 0.01 inch (2.49 Pa) of water at the location of the penetration for the time period equivalent to the fire-resistance rating of the construction penetrated.
    - - - - 5. Grille openings located in a ceiling of a fire-resistance-rated floor/ceiling or roof/ceiling assembly shall be protected with a listed ceiling radiation damper installed in accordance with Section 716.6.2.1.

    Basically, the common requirements between many sections which may be applicable is the:
    - and shall be constructed of steel not less than 0.019 inch (0.48 mm) (26 gage) in thickness
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