# Fire Barrier Shaft "Supporting Construction"



## Glennman CBO (Mar 15, 2010)

2006 IBC, section 706, VB construction.

I've seen two different methods of construction of shafts that continue through floors.

One is where the fire barrier wall above the penetrated floor is setting on top of the floor in a platform frame fashion. The drywall inside the shaft is continuous where it passes through the floor, and the drywall on the outside of the shaft stops at the intersecting ceiling, and starts again above the floor. The rim of the floor is solidly blocked, but there is no drywall in the concealed space (this is not a suspended ceiling, it is a hard lid). I've also seen this method where they have installed drywall between the intersecting perpendicular joists, or, they would install drywall at the "rim" joist.

The other method I've seen is where the shaft wall is framed in a balloon frame method, and the drywall is continuous through the floor on both sides (inside and outside the shaft) and there is a "hollow vertical space" at the floor line that is fireblocked. The floor is setting on its own independent wall in a platform fashion, and does not intersect into the shaft wall. There are then (2) walls, one makes up the shaft, and the other makes up the parallel wall supporting the floor. The space between the (2) walls is fireblocked at the top.

Which method, or methods, meets the requirements for continuity, as well as meeting the requirement of rating the supporting construction? (I hope I described all this OK).


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## texasbo (Mar 15, 2010)

Re: Fire Barrier Shaft "Supporting Construction"

Just off the cuff, without drawings, I would approve all methods described. However, in the first condition, where the shaft is supported by the floor/ceiling construction, the supporting construction would need to be rated.


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## Coug Dad (Mar 15, 2010)

Re: Fire Barrier Shaft "Supporting Construction"

A big challenge is that the supporting construction for a fire barrier has to be at least the rating of the fire barrier.  The IBC permits large buildings in Type II-B construction.  The rated fire barriers for the stairs, hoistways and shafts can not bear on a non rated floor assembly.


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## pyrguy (Mar 15, 2010)

Re: Fire Barrier Shaft "Supporting Construction"



			
				Coug Dad said:
			
		

> A big challenge is that the supporting construction for a fire barrier has to be at least the rating of the fire barrier.  The IBC permits large buildings in Type II-B construction.  The rated fire barriers for the stairs, hoistways and shafts can not bear on a non rated floor assembly.


Agreed! You should be able to follow the fire rating all the way from foundation to roof deck ( or rated lid)


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## Glennman CBO (Mar 15, 2010)

Re: Fire Barrier Shaft "Supporting Construction"

Makes sense. This came up in one of our code update staff meetings. One of our plans examiners has only seen it one way (balloon style) and thinks that's the only way to do it, regardless of whether or not the intersecting floor is rated.


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## EPrice (Mar 15, 2010)

Re: Fire Barrier Shaft "Supporting Construction"

2006 IBC 706.5 requires the fire barrier wall to extend from the top of the floor below to the "underside of the floor or roof slab or deck above".  IMO if the wall and floor are platform framed as described in your first method, the wall does not extend to the underside of the floor deck above, but rather, extends to the ceiling membrane.  To meet the above requirement in 706.5, it would need to be shown that the solid blocking between joists meets the required rating of the wall, and the joists treated as penetrations through the wall.  Now if this shaft is for a stair enclosure, then we still have a problem, since these joist penetrations would be in violation of 1020.1.2.


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## RJJ (Mar 15, 2010)

Re: Fire Barrier Shaft "Supporting Construction"

agree with Texasbo!


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## texasbo (Mar 16, 2010)

Re: Fire Barrier Shaft "Supporting Construction"



			
				Glennman CBO said:
			
		

> Makes sense. This came up in one of our code update staff meetings. One of our plans examiners has only seen it one way (balloon style) and thinks that's the only way to do it, regardless of whether or not the intersecting floor is rated.


Glennman, keep in mind that as others have said, it would not just have to be the supporting floor that is rated, but the elements supporting the supporting floor.


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## RJJ (Mar 16, 2010)

Re: Fire Barrier Shaft "Supporting Construction"

Many DP's miss this when submitting plans for review. The supporting elements must be protected.

Stair towers often get over looked.


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