1. ATTENTION returning members. If you are coming here from the old forum for the first time, you will need to reset you password. However, we had an email problem getting password reset links set out to a lot of the email addresses. That problem is temporarily rectified but IF you still have an issue, email me direct at info@thebuildingcodeforum.com and I will give you a temporary password.
    Dismiss Notice
  2. Welcome to the new and improved Building Code Forum. We appreciate you being here and hope that you are getting the information that you need concerning all codes of the building trades. This is a free forum to the public due to the generosity of the Sawhorses, Corporate Supporters and Supporters who have upgraded their accounts. If you would like to have improved access to the forum please upgrade to Sawhorse by clicking here: Upgrades
    Dismiss Notice

DWV in Return Air Ducts

Discussion in 'Mechanical Codes' started by jar546, Aug 15, 2019 at 9:25 PM.

  1. jar546

    jar546 *****istrator

    Joined:
    Oct 16, 2009
    Messages:
    6,818
    Likes Received:
    467
    Such as this. What is your opinion?
    IMG_9897.JPG
     
  2. ICE

    ICE Sawhorse

    Joined:
    Jun 23, 2011
    Messages:
    8,257
    Likes Received:
    874
    Fluid dynamics is a complicated subject. Sometimes it comes down to which way the wind is blowing.
     
  3. steveray

    steveray Sawhorse

    Joined:
    Nov 25, 2009
    Messages:
    6,427
    Likes Received:
    849
    What's my opinion? or what code section would I use to deny that crap?

    307.6 Piping materials exposed within plenums. Piping
    materials exposed within plenums shall comply with the provisions
    of the International Mechanical Code.

    308.3 Materials. Hangers, anchors and supports shall support
    the piping and the contents of the piping. Hangers and strapping
    material shall be of approved material that will not promote
    galvanic action.
    308.4 Structural attachment. Hangers and anchors shall be
    attached to the building construction in an approved manner.
     
  4. mtlogcabin

    mtlogcabin Sawhorse

    Joined:
    Oct 17, 2009
    Messages:
    7,335
    Likes Received:
    832
    I assume this is a SFR and since the IRC is silent on this I will use the IPC and IMC.

    2012 IPC
    307.6 Piping materials exposed within plenums.
    All piping materials exposed within plenums shall comply with the provisions of the International Mechanical Code.

    602.2.1 Materials within plenums.
    Except as required by sections 602.2.1.1 through 602.2.1.5, materials within plenums shall be noncombustible or shall be listed and labeled as having a flame spread index of not more than 25 and a smoke-developed index of not more than 50 when tested in accordance with ASTM E 84 or UL 723.
    Exceptions:
    1. Rigid and flexible ducts and connectors shall conform to Section 603.
    2. Duct coverings, linings, tape and connectors shall conform to Sections 603 and 604.
    3. This section shall not apply to materials exposed within plenums in one- and two-family dwellings.
     
    ADAguy and Ty J. like this.
  5. HForester

    HForester Member

    Joined:
    Sep 21, 2015
    Messages:
    179
    Likes Received:
    56
    "I assume this is a SFR and since the IRC is silent on this, I will use the IPC and IMC."

    The IRC is intended to be an all encompassing bible for SFRs. Everything that one needs to build SFRs is in that book. The IRC covers ductwork/return air chases ("plenum") and DWV piping. The IRC does have not a prohibition of PVC piping in a plenum. Cherry picking regulations from other I-Codes to apply to an SFR is standing on shaky ground.
     
  6. Ty J.

    Ty J. Sawhorse

    Joined:
    Aug 2, 2017
    Messages:
    511
    Likes Received:
    213
    Since when?

    It is the exact opposite. The IRC is intended to represent the most common and typical configurations and construction methods and is not intended to be all encompassing. Where not covered by the IRC, more expansive codes such as the IBC/IPC/IMC/etc. are to be used.

    R104.11 Alternative Materials, Design and Methods of Construction and Equipment
    The provisions of this code are not intended to prevent the installation of any material or to prohibit any design or method of construction not specifically prescribed by this code, provided that any such alternative has been approved. An alternative material, design or method of construction shall be approved where the building official finds that the proposed design is satisfactory and complies with the intent of the provisions of this code, and that the material, method or work offered is, for the purpose intended, not less than the equivalent of that prescribed in this code. Compliance with the specific performance-based provisions of the International Codes shall be an alternative to the specific requirements of this code. Where the alternative material, design or method of construction is not approved, the building official shall respond in writing, stating the reasons why the alternative was not approved.
    IRC is the prescriptive "conventional/typical" playbook, whereas the other codes (IMC, IPC, etc.) allow for performance based "non-conventional/atypical" methods where supported by quantitative testing.
     
  7. mtlogcabin

    mtlogcabin Sawhorse

    Joined:
    Oct 17, 2009
    Messages:
    7,335
    Likes Received:
    832
    You missed the point of the code path that I outlined

    It was to verify that since the IRC was silent on this installation and the mechanical code has an exception for materials in a plenum in a one and two family dwelling that the installation in the photo is not a violation of the IRC and therefore allowed.
    Inspectors will sometimes call out things that just don't look right. As a building official I have to make the final determination if it is not specifically addressed in the code. Finding an answer in the IMC for a IRC building and basing my decision on another adopted code is not "shaking ground".
     
    jar546 likes this.
  8. Pcinspector1

    Pcinspector1 Platinum Member

    Joined:
    Oct 28, 2009
    Messages:
    2,989
    Likes Received:
    391
    Seams are taped and the tape meets UL 181, nonmetallic insulated duct board meets a Class 1 rating, though I hardly see information on the duct material.
     

Share This Page