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Thread: 3 hour firewall

  1. #1
    Join Date
    Jul 2004
    Location
    Sumter, South Carolina
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    272

    3 hour firewall

    what is the best method of fire-stopping 4" sq's with rings mounted on box brackets to metal studs in a 3 hr fire rated party wall? GWB
    Electrical Contractor, Master Electrician.

  2. #2
    Join Date
    Sep 2004
    Location
    Durham, NC
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    5,143
    Fire paddies, encasing the outside of your box, with three hours, I believe that'd be double sheet rock or equilvant.
    Get the correct gypsum mud ring to suit depth.
    There is a seperation distance required for circuit service on respective sides of the wall, "in respect to each other"
    = : )

  3. #3
    Join Date
    Feb 2003
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    274
    I don't believe, but I could be wrong, that fire pads are rated for three hours. You would have to have the framer build you a fire box into the wall. You will have to search UL for an assembly that matches you situation. BTW a three hour rating takes three layers of 5/8 board on each side of the wall.

  4. #4
    Join Date
    Jul 2008
    Location
    Lake Ridge, VA
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    1,794
    Quote Originally Posted by scwirenut
    what is the best method of fire-stopping 4" sq's with rings mounted on box brackets to metal studs in a 3 hr fire rated party wall? GWB
    get some of these: http://www.jmfirestopping.com/jm/lis...Datasheets.pdf

  5. #5
    Join Date
    May 2008
    Posts
    721
    You can put as many boxes as close as you like in one wall without pads. It's when you penetrate the other wall within, I want to say 2' of a opening on the oposite wall that pads are required. Fire stop is expensive. So plan well. Call a company like Specseal or 3M. You can get a application booklet. I'd also contact your local inspectors. See what their take on it is.

  6. #6
    Join Date
    Sep 2004
    Location
    Durham, NC
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    Welp 1-2 hour on puddie pads, 3 hours seems extreme, I've never coved my work but there has been alot of cover ups ...
    = : )

  7. #7
    Join Date
    Oct 2003
    Location
    Southern California
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    1,778
    If your AHJ is on the ball you are probably up the creek. Fire Pads are only good for two hours and the IBC exception for no pads on boxes is only for two hour walls. 712.3.2 exc 1 IBC 2006

    There is a chance that some manufacturer has a system or product for use in a 3 hour wall.

    The lack of tested products for this application would dictate that the 3 hour wall be built and then a furred wall be built in front of that for electrical, plumbing etc.

    In our city the integrity of the fire resistive construction comes first. We simply do not allow anything that is not listed for the use.

    Your AHJ may allow something different.
    I'm an Inspector, what do I know?

  8. #8
    Join Date
    Jan 2005
    Posts
    907
    go back to the architect or engineer

  9. #9
    Join Date
    Apr 2006
    Location
    Simi Valley, CA
    Posts
    6,978
    I agree with Larry.
    I can build anything you want if you draw a picture of it on the back of a big enough check.

    There's no substitute for hard work....but that doesn't mean I'm going to give up trying to find one.

    John Childress
    Electrical Inspector
    IAEI / CEI / C10
    Certified Electrical Inspector

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