Return to index: [Subject] [Thread] [Date] [Author]

Re: Area separation walls

[Subject Prev][Subject Next][Thread Prev][Thread Next]
One note to add to this discussion:

 Area separation wall and adjoining structure need to be designed and
detailed so that the structure on one side of the wall which may be
experiencing a fire can perform independently of the structure on the other
side of the wall.  This means that the structure on the fire side of the
wall can collapse while the structure on the other side still stands.

Lanny J. Flynn, P.E., S.E.
Regional Engineer
AISC Marketing, Inc.
email: flynn(--nospam--at)

-----Original Message-----
From: Sprague, Harold O. <SpragueHO(--nospam--at)>
To: seaint(--nospam--at) <seaint(--nospam--at)>
Date: March 03, 2000 11:12 AM
Subject: RE: Area separation walls

>Tarno Coleman and I had an off line discussion about penetrations of fire
>walls.  I thought that the thread might prove to be informative to the
>entire list.
>Tarno pointed out the distinction between area separation walls and
>occupancy separation walls.
>Harold Sprague
> -----Original Message-----
> Sent: Wednesday, February 23, 2000 1:31 PM
> To: SpragueHO(--nospam--at)
> Subject: Re: RE: Area separation walls.
> Harold
> The code has many different requirements that specify fire resistive
> construction.  Different types of separations (occupancy; area;
> specific) may have the same hourly fire-resistant and can result in
> confusion.  All walls with a equal fire-resistance hourly rating are
> not necessarily the same for code purposes. An area separation wall
> a special critter.  Exit enclosures are an example of specific
> requirements for stairway protection.
> The following is from the 1997 UBC and the 1997 UBC Handbook:
> 1997 UBC Volume 1
> "504.6 Area Separation Walls.
> 504.6.1 General. Each portion of a building separated by one or more
> area separation walls that comply with the provisions of this
> may be considered a separate building. The extent and location of
> area separation walls shall provide a complete separation.
> When an area separation wall also separates occupancies that are
> required to be separated by an occupancy separation, the most
> restrictive requirements of each separation shall apply."
> "504.6 Area Separation Walls. In Section 302 the code introduced the
> concept of the fire-resistive separation, designated the "occupancy
> separation," where the openings in the separation wall are protected
> by fire-protection assemblies. The Uniform Building Code has a
> type of fire-resistive separation, which is called the "area
> separation wall." The intent of the code is that the function of the
> wall is exactly as its name implies-a vertical wall that separates
> areas. This is to distinguish it from an occupancy separation that
> be horizontal. Structural members that penetrate area separation
> could limit the effectiveness and would not comply with the
> that states such walls "shall provide a complete separation." Any
> member that passes through an area separation wall could affect the
> integrity of the required fire-resistive construction. However, the
> code does not prohibit western platform framing to divide a two-hour
> area separation wall if solid blocking is provided within the floor
> roof cavity. See Footnote 2 for a reference to an article by Paul
> Sheedy which illustrates this concept."  (emphasis added)
> >>> "Sprague, Harold O." <SpragueHO(--nospam--at)> 02/23/00 08:38AM >>>
> Tarno,
> I have often seen stairwells in buildings with rated enclosures that
> only
> had to be sealed at the top to prevent smoke from entering the stair
> enclosure.  Or another one was a small office adjacent to a
> manufacturing
> facility.  The roof structure went through uninterrupted.  They were
> referred to as area separation walls.  This is very common in the
> prefab
> metal building industry.
> Is this a correct interpretation?
> Regards,
> Harold Sprague
> > -----Original Message-----
> > Sent: Wednesday, February 23, 2000 10:33 AM
> > To: SpragueHO(--nospam--at)
> > Subject: Area separation walls.
> >
> > Excuse the off-line reply, but our mail system does not permit
> access
> > to the list.
> >
> > Our interpretation of the UBC regarding area separation wall is
> > no structural members pass through it.  The logic being if the
> member
> > fails on the fire side it may pull the wall apart.
> >
> > As an alternate method on one job, we accepted 2-hour protection
> > beams and columns supporting the beam that passed though the area
> > separation wall. (sismic tie) This building was fully sprinklered.
> >
> >
> > ps: I appreciate your thoughtful and incisive responses to the
> >
> >
> >
> > Tarno Coleman, PE
> > Plan Check Engineer
> > 503.566.3964
> > e-mail: tcoleman(--nospam--at)
> > Marion County Building Inspection
>> PO Box 14500, Salem, Oregon  97309