Structural stability for Fire Walls- 2006 IBC, Section 705.2

Does anyone on here have details (structural and/or architectural) showing how a FIRE WALL (previously known as "Area Separation Walls" in the UBC) can be designed to comply with Section 705.2 of the 2006 IBC?

I'm finding out a lot of misinterpretation/confusion as to what it means to "...have sufficient structural stability under fire conditions to allow collapse of construction on either side without collapse of the wall for the duration of time indicated by the required fire resistance rating."

How are structural engineers, plan examiners dealing with this requirement and what are you getting/accepting for such details? The ICC books and training manuals have minimal information and details dealing with this topic!

Please post the details to this thread.
Original Post
Basically, the fire wall must be free-standing, on its own footing. Its best that no structural members be attached to the wall [should run parallel to it, or be supported separately from fire wall]. The wall itself must be designed to be structurally stable and capable of meeting loading requirments for its height and width; and reinforced to provide necessary stability

Is possible to frame structural members "INTO" the wall, but they must be free to rotate out of the wall when they burn through or collapse under fire conditions. Formmlly and firmly attaching them to the wall will cause them to pull over at least part of the wall in a collapse-- and that cannot happen in a fire wall situation!
NCMA Tek Note 5-8B gives details for a masonry fire wall at One detail is a double wall that allows collapse of one without the other.

I have also seen a gypsum "shaftwall" assembly that is clipped to wood-frame construction on either side. The "shaftwall" remains in place when either side collapses.

You are correct in that the Gypsum Association Design Manual has some good assemblies listed for FIREWALLS (Area Separation Walls), starting with GA File ASW1000 through ASW2600.

What I was after though, was the detailing at the top of these walls and bottom that would show the structural independence of the Fire Wall to verify compliance Section 705.2.

Basically details in line with what Ralph posted above!

As these "Fire Walls" start showing up on the drawings after January, 2008, I'm hoping that some direction will be provided on what to look for in regards to "structural stability" which was intended under the 1997 UBC, but not specifically stated in code language as we now have in the 2006 IBC.

Surely someone has details that we can learn from Smile
Okay guys, but am I missing something here?

How is a concrete or masonry firewall supposed to be supported seismically with out tieing it into one side or the other of the building framing.

This seems WORSE than a MFL (Maximum Foreseeable Loss) wall from FM.

What are the thoughts of others?
Great Question.

I'd like to add another question, "What specifically is the difference between an Area Separation Wall (UBC)and a Fire Wall (IBC)?"

I have heard second hand that the collapse language was part of the UBC intent since the concept was first introduced into the code.
The Structural Engineers of South California (SEAoSC) light-framing construction committee has issued a "Seismology Opinion" (attached) in regards to continuity of plywood diaphragm sheathing in 2 and 3 hour fire walls.

Their opinions are well founded and every engineer and architect designing fire walls using Section 705 of the IBC should be aware of the recommendations in the published opinion. Code officials and structural/fire-and-life-safety plan examiners can use the opinion for background information about the subject.


We are using a 3-hr CMU Fire Wall to add on to a Type 1B 7 story 2-hr concrete frame structure. In order to make the Fire Wall have structural stability we are designing the addition structural frame as 3-hr to match the Fire Wall and we are tying the wall laterally into the addition. The idea is that the Fire Wall and 3-hr structure having the same rating keeps both pieces standing for the duration of time required by the fire rating.

We have not yet presented to the AHJ.
We are building a fairly large 17 acre industrial park. The new codes effective this year on permits that are submitted this year are requiring a two hour firewall at property line. There are several stipulations regarding this wall such as 20 feet minimum before 2007 and only 10 feet now and before 2007 only a one hour wall was necessary now a 2 hour is required. All of our buildings are to have active fire sprinkler system. One city offical summarised the fire wall as a protection from an adjacent building. This he explained makes it unnecessary for their to be a fire wall at a property line where no future adjacent building could be built such as a roadway, path, canal or etc. However now I can't get a confirmation of this decision. What information do you have or can you direct me to an answer in this matter. It seems that no one really knows even our Architect.
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