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Any restrictions prevening shaft walls from bearing structure about it?

L

lunatick

Silver Member
Joined
Apr 14, 2011
Messages
120
Hotel, 3 story building, sprinkled, wood construction Type VA. IBC 2006/2009

Looking through the code sections, I do not see anything that would prohibit the shaft walls from bearing loads or being structurally independent from the rest of the structure. If anything, Fire Barrier Continuity states the wall goes from floor to underside of floor above, would suggest the shaft wall can be built at least on this deck.

However, I get the feed back these things are supposed to be independent, etc. What am I missing, please cite.

What I am proposing to do is install blocking in the shaft wall and hanging joists up against the wall?

thanks
 
fire walls need to be indepenant maintion integrety if one side fails, nothing that I can thinkp of about shaft walls not all to suport othe structure. lower level rated walls, columns and the like support other structure above
 
Unless it clearly says something cannot be done the building official has to allow it to be done.

The whole idea of a rated wall is to assure that it stays in place.
 
Commish,

I am not going to argue you your theory.

What I am inquiring is, where in the codes or cited references does it state that the shaft cannot be bearing and that it be independent in design?

IBC 2006, 2009 and 2012 a Shaft is defined as meeting the requirements for either Fire Barriers either or both Horizontal Assemblies for continuity.

Wherein if it were a Fire Wall, that assembly contains information about structural independence, etc.

However Fire Barriers do not.
 
2006 IBC -

707 shaft -Shaft enclosures shall be constructed as fire barriers

in accordance with Section 706

706.5 Continuity. Fire barriers shall extend from the top of the

floor/ceiling assembly below to the underside of the floor or

roof slab or deck above and shall be securely attached thereto.

Such fire barriers shall be continuous through concealed

spaces, such as the space above a suspended ceiling.

***The supporting

construction for fire barrier walls shall be protected to

afford the required fire-resistance rating of the fire barrier supported,***

except for 1-hour fire-resistance-rated incidental use

area separations as required by Table 508.2 in buildings of

Type IIB, IIIB and VB construction.

This section surrounded by *** usually causes a few issues especialy in wooden construction
 
That is why CMU elevator shafts are popular in type V buildings they can stand independetly, whe in a type I buildg shaft walls (sheet rock) canbe used. My experiance is that CMU is the way to go no mater what the construction type for shafts and stair well enclosures.

I concure with Builder Bob that ther is nothing that prohibits the shaft from being laod bearing
 
Cavity shaft wall systems using CH studs are non-bearing.

Perhaps that is the source of the confusion.
 
Agree with BB....they miss that supporting construction thing alot....but can be bearing.......as a quick aside.....How far do you all take the "supporting construction" thing? Just the floor holding it up? or the roof it is braced to?
 
Product literature for steel stud shaft wall type system shows the shaft wall system bearing on the floor that is supported with fireproofing on the structural frame. The manufacturers know that continuity is required for the fire barrier wall system at the supporting floor.

Code congress has told me that if the building is not protected Construction (A-type) then the protected construction for the shaft or fire barrier wall support must be extended to the next bay along floor, beam and column lines. You protect the part of the building that is supporting the fire barrier.

I tell my clients if a fire barrier for a shaft is required, then use CMU or we have to use fireproofing at specific locations and framing around the shaft may be different than other areas of the structure.

A 3-story hotel building usually has a 1-hour rated floor system and the shafts are required a 1-hour rating. Therefore, the shaft wall (fire barrier) can bear on the 1-hour rated floor system. Hotels chains I have done require protected construction regardless what the code requires. The post listed Type VA which is protected Construction.
 
IMO, the way this is being described by what is written and published in the code literature. This design intent isn't being expressed. Very vague and very faint.

Some have described these walls as Fire Walls. Funny, there exists such a thing in the code. Then why not, even if by exception (allowing for fire barriers where a structural issue may not exist), just state it that way. Rather than state it is a fire barrier and then interpret this condition to nearly a fire wall.
 
Steveray === to answer your question -"as a quick aside.....How far do you all take the "supporting construction" thing? Just the floor holding it up? or the roof it is braced to? "

Short answer, we require the entire sturture to be protected unless the design professional can provide documentation that the structure in place will support the shaft wall for the time required.

If it wood, then they have to provide documentation to indicate the wood members have enough sacrificial mass to continue supporting the framework for the time required when exposed to fire conditions. (NDS guide - Chapter 11)

otherwise the structural component(s) are dificult to address as a layman, to many varible exists - simple span, continious span, shear wall, drag strut, etc.....

most often, we get a one hour rated ceiling assembly for a building with a stairway shaft if the building is non-sprinklered.
 
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