I've got a two-story balloon frame house that is gutted. I have to install fire blocking between studs in the wall cavity. Do I install the fire blocking wherever there is a floor, or wherever there is a ceiling? (Or both?)

  • I don't deal with any balloon framing in my area but fireblocking isn't structural, it is blocking an air supply. I would tend to think that you would use normal procedures but would like to hear if there are differences from someone more experienced with balloon framing. Probably pics or examples would help too.
    – DMoore
    Commented Feb 3, 2016 at 21:41
  • Yes, this is why I asked the question. If I install the blocking level with the ceiling of the 1st Floor, it protects the 2nd Floor joists, but if fire came up through a hole in the ceiling, it could eat away at the structure of the 2nd Floor. If I install the fireblock level with the 2nd Floor, it exposes the 2nd Floor structure to flames from below. Very confusing.
    – Mattzees
    Commented Feb 3, 2016 at 21:45
  • This video gives some suggestions: preppernextdoor.wordpress.com/2013/01/01/… Also, you might stop by your local firestation and talk with the firefighters.
    – Yehuda_NYC
    Commented Feb 3, 2016 at 21:57
  • Thank you for that. This one is more comprehensive: youtube.com/watch?v=dSRpUvSD0l4&feature=player_embedded
    – Mattzees
    Commented Feb 3, 2016 at 22:38
  • 2
    The other reason we stopped using baloon framing is that it became harder to get 20'-long 2x4's... but, yes, fireblocking is an issue. I don't think my inspector checked for that before I bought this pace; guess I should make sure sometime.
    – keshlam
    Commented Feb 3, 2016 at 23:29

2 Answers 2


Blocking is required wherever a fire or draft can pass from horizontal plane to a vertical plane or vice versa. In otherwords, where the wall meets the floor and the floor meets a ceiling. If fire can pass through one section and travel to another, it needs to be blocked. The 2012 IRC code says that a 16" section of fiberglass insulation will suffice as fireblocking. If you are insulating the outside walls as it is, you will be covered.

Code book page

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  • If I recall, for fiberglass insulation to be used as fireblocking it has to be unfaced.
    – Comintern
    Commented Feb 4, 2016 at 4:57
  • That may be so. My memory does not serve me that well all the time, so I will temper what I write next with that. I remember elsewhere in the code, if the insulation is in a confined space, like a stud bay, and not to close off a soffit, the facing is acceptable. I will check to see if I can find it in the exceptions and post it.
    – Jack
    Commented Feb 4, 2016 at 16:25
  • I found it, see edit
    – Jack
    Commented Feb 4, 2016 at 16:36

Whoa...who says you, "have to install X-type (fire resistant) 5/8" sheetrock on my exterior walls anyway, and so that satisfies the lateral fire blocking requirement."

First, Sheetrock on exterior walls is for fire resistance or lateral resistance, not for fire blocking.

Second, sheetrock for fire resistance on exterior walls is ONLY required when your exterior wall needs to be "fire rated". Fire rating for residential construction is ONLY required if the house is constructed too close to the property line...and then only on that one side of the house.

Third, if it's for "lateral resistance", then it must be installed in a certain pattern and nailed properly (correct size and spacing of nails).

  • All local building codes around here. That was finished and done a long time ago.
    – Mattzees
    Commented Apr 29, 2017 at 15:39

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