Results 1 to 6 of 6
  1. #1
    Join Date
    Mar 2007
    Location
    Rochester, New York
    Posts
    23

    Default Cables Stapled To Bottom Edge Of Roof Rafters

    I understand that NM cables (of certain gauge) can not be attached to the bottom of floor joists and that more than 2-cables should not be secured with staples, but is there a code issue with NM cables stapled to the underside of roof rafters, as long as they are stapled at least every 4.5'?

    ***IMPORTANT*** You Need To Register To View Images ***IMPORTANT*** You Need To Register To View Images
    2018 ASHI InspectionWorld
    Dave Tontarski
    Act in haste....repent in leisure

  2. #2
    Join Date
    Mar 2009
    Location
    Colorado Front Range
    Posts
    601

    Default Re: Cables Stapled To Bottom Edge Of Roof Rafters

    Code language pertaining to NM-B type cable installation attached to floor joists addresses just that - floor joists. Much of the intent is that by drilling through floor joists the cable is better supported if someone elects to use the cable as a "hanger bar" for clothes and other items and might prevent some possible damage.

    Attaching cable to the bottom of roof joists presents another problem in that the temperature is much higher at the top of an attic space than on the ceiling joists at the bottom of the space and it is quite unlikely d-rating for this was taken into account. If you play with an infrared temp tester you can see this is really a big deal.

    And, if 2 X 4 trusses are used they can't be drilled anyway.

    So no, the drilling versus stapling isn't an issue with roof joists but other things might be/probably are.

    Occam's eraser: The philosophical principle that even the simplest solution is bound to have something wrong with it.

  3. #3
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    26,244

    Default Re: Cables Stapled To Bottom Edge Of Roof Rafters

    The way they are stapled is incorrect.

    As Bill said, derating needs to be applied, both for ambient temperature in the attic and for lack of maintaining spacing.

    Trusses of any size are not permitted to be drilled, no engineered trusses or engineered lumber are permitted to be drilled unless specifically addressed by the enginer.

    Rafters, floor joists, studs are allowed to be drilled, cut, notched with specified limitations, no restriction is stated about drilling, cutting 2x4 any differently than 2x6, 2x8, etc. - if a 2x4 engineered truss then not allowed to drill anyway (again, regardless of lumber size).

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  4. #4
    Join Date
    Mar 2007
    Location
    Rochester, New York
    Posts
    23

    Default Re: Cables Stapled To Bottom Edge Of Roof Rafters

    Thanks!

    Dave Tontarski
    Act in haste....repent in leisure

  5. #5
    Join Date
    Jul 2010
    Location
    Wisconsin
    Posts
    274

    Default Re: Cables Stapled To Bottom Edge Of Roof Rafters

    Quote Originally Posted by David Tontarski View Post
    is there a code issue with NM cables stapled to the underside of roof rafters?
    If there is a permanent stair or ladder to the attic then you need to comply with NEC 334.23 which takes you over to 320.23. Seems like this might be a walk up attic, bunch of "stuff" in there??? If it is, and the cables are within 7 feet of the floor it is wrong. If the access is via scuttle opening then it's only an issue if it's within 6 feet of the scuttle opening.



  6. #6
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    26,244

    Default Re: Cables Stapled To Bottom Edge Of Roof Rafters

    Quote Originally Posted by Mike Kleisch View Post
    If there is a permanent stair or ladder to the attic then you need to comply with NEC 334.23 which takes you over to 320.23. Seems like this might be a walk up attic, bunch of "stuff" in there??? If it is, and the cables are within 7 feet of the floor it is wrong. If the access is via scuttle opening then it's only an issue if it's within 6 feet of the scuttle opening.
    As low as the peak is above the ceiling joists, it would have an access opening and only be a problem within 6 feet of the opening.

    - 320.23 In Accessible Attics.
    - - Type AC cables in accessible attics or roof spaces shall be installed as specified in 320.23(A) and (B).
    - - - (A) Where Run Across the Top of Floor Joists. Where run across the top of floor joists, or within 2.1 m (7 ft) of floor or floor joists across the face of rafters or studding, in attics and roof spaces that are accessible, the cable shall be protected by substantial guard strips that are at least as high as the cable. Where this space is not accessible by permanent stairs or ladders, protection shall only be required within 1.8 m (6 ft) of the nearest edge of the scuttle hole or attic entrance.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •