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fir down (chase) and fire code

txkevin | Posted in Construction Techniques on June 22, 2007 10:08am

I have built a horizontal chase in the garage area that is approx 3×3 square in the garage of my new construction.  This chase is to enclose the range hood vent pipe and some hvac venting to the exterior wall. 

The box uses the wall that is common to the kitchen and the garage for one side.  The bottom is 2×4 frame ready for drywall.  The front is 3/4 plywood to be covered by drywall . The top is web floor truss so it will remain uncovered. The back is a 2×4 wall that will get drywall on the kitchen side. 

Am I going to have code problems for not having a fire break in the top attached to the floor trusses  or will the drywall on 3 sides suffice (one side being the kitchen side of the wall) ?  This is a 2 story home.

I also have a crown step (1′ down 2′ in) in the master bedroom that is simply 2×4 framing and that will only get drywall on 3 sides.  Will this get similar treatment?

Thanks in advance.

Kevin

 

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Replies

  1. User avater
    CapnMac | Jun 23, 2007 12:45am | #1

    Am I going to have code problems for not having a fire break in the top attached to the floor trusses  or will the drywall on 3 sides suffice (one side being the kitchen side of the wall) ?  This is a 2 story home.

    You amy be tired of the refrain, but the answer is:  It's down to the BI/AHJ.

    Now, if you follow the "rules" for the wallboard up and around and to the ceiling again--you will be "right."  So, if you need "X" board, or fire-caulk, or mineral wool, whatever--you need to carry that right around the furr down.

    If, what the AHJ "wants" is that the seperation "attaches" to the "living" side and not the "garage" side (or if the BI is ameanable to the idea, you can jsut carry the seperation up past the framing for the soffit entire.  (In houston, your best bet is to build the wall & ceiling, then apply the soffit framing on top of that.)

    Occupational hazard of my occupation not being around (sorry Bubba)
    1. txkevin | Jun 23, 2007 01:22am | #2

      I really appreciate your always responding to what must be pretty basic questions for a pro.

      1. User avater
        CapnMac | Jun 23, 2007 08:09am | #4

        responding to what must be pretty basic questions for a pro.

        LoL!  I'm no "pro," I've just done enough TI (Tennant Improvement) work in enough different jurisidctions, from havign to change drawings to having to add rock wool & fire pookie to just have a "reflex" or two . . . <g>

        Some of which is all sleit-of-hand; a two-hour rated waal w/o rock wool needs 2 layers of 5/8' "X" board with fully-lapped joints.  Both UL and Gyspum Bulding Org so say. 

        But, it's real hard to rock the wall in someone else's lease space . . . Uh, can I get a lil' help here, Mr BI?

        Be still waiting on that "We'll get right back to you . . . "Occupational hazard of my occupation not being around (sorry Bubba)

  2. dovetail97128 | Jun 23, 2007 02:24am | #3

    txkevin,

    One way to look at these situations is to envision a flame path.

    Can a fire travel through a wall(stud) cavity and into your chase. If so then the lid of the chase needs fire protection. Easy to check , can you reach into a stud cavity and then see your hand as being inside the chase?
    If you can see you hand then that area needs blocking.

    If any means for flame spread into the cavity created by your chase is blocked by either solid 2 x material or type X rock you "generally" don't need to rock the lid of the chase.

    But as CapnMac says best to check with the inspector.

    "Poor is not the person who has too little, but the person who craves more."...Seneca

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