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Fire Barriers to floor or roof deck above. Any exceptions?

N

nealderidder

Sawhorse
Joined
Dec 7, 2010
Messages
420
Location
Sacramento, CA
I'm curious if anyone has had success with an AMMR or similar that allowed them to terminate a Fire Barrier at a Horizontal Assembly vs. a floor or roof deck. I've got a TI project that has a very tall interstitial space above the first floor. The floor to floor from 1st to 2nd is 20'. My 1fl ceilings (suspended) are going to be at 10'.

This is an existing building and there is an extensive existing catwalk (all steel, attached to steel beams) the bottom of which is around 10'-9". I'm going to have 4 control areas on the 1fl. To take those control area walls up to the floor deck (metal pan/concrete) above at 20' I'm going to either have to demo that catwalk or build a 1hr wall "around" it. Sounds very fussy! The catwalk is useful and demoing portions of it will result in dead ends that didn't exist before.

I'm wondering what kind of luck I'll have asking the AHJ to allow us to terminate at a 2hr horiz. assy. vs. the floor deck.

I'm also wondering where this requirement came from? Is it safer to go to a 2hr floor assembly than it is to a 2hr horizontal ceiling assembly?

Thanks,
 
I believe this is pretty well allowed these days (terminating at a lid) as much as I do not like it....

1023.2 Construction. Enclosures for interior exit stairways
and ramps shall be constructed as fire barriers in accordance
with Section 707 or horizontal assemblies constructed in
accordance with Section 711, or both.
 
If terminating a fire barrier at a horizontal assembly and the horizontal assembly has a concealed space, then the fire barrier must still extend through the horizontal assembly to the sheathing, slab, or deck above, because a fire barrier must extend through concealed spaces.
 
RLGA said:
If terminating a fire barrier at a horizontal assembly and the horizontal assembly has a concealed space, then the fire barrier must still extend through the horizontal assembly to the sheathing, slab, or deck above, because a fire barrier must extend through concealed spaces.
Click to expand...


If doing for chemical control, can they put a one hour ceiling on it??
 
cda said:
If doing for chemical control, can they put a one hour ceiling on it??
Click to expand...

This is what I would like to do.... I think I see what steveray and CDA are saying. The CBC section is 414.2.1:

..by fire barriers, constructed in accordance with section 707 or horizontal assemblies constructed in accordance with section 711, or both.

So if horizontal assemblies are required can I make my ceiling a horiz. assy.?

If I do, that doesn't negate the requirement that the walls be fire barriers and we're back to what RLGA is saying - we need to meet the 707 requirement for fire barriers which means they need to go to floor or roof deck.

This begs the question - In what situation could I actually use a horizontal assembly as a boundary of a control area?
 
707.5 Continuity. Fire barriers shall extend from the top of
the foundation or floor/ceiling assembly below to the underside
of the floor or roof sheathing, slab or deck above and
shall be securely attached thereto. Such fire barriers shall be
continuous through concealed space, such as the space above
a suspended ceiling. Joints and voids at intersections shall
comply with Sections 707.8 and 707.9
Exceptions:
1. Shaft enclosures shall be permitted to terminate at a
top enclosure complying with Section 713.12.
2. Interior exit stairway and ramp enclosures required
by Section 1023 and exit access stairway and ramp
enclosures required by Section 1019 shall be permitted
to terminate at a top enclosure complying with
Section 713.12.

713.12 Enclosure at top. A shaft enclosure that does not
extend to the underside of the roof sheathing, deck or slab of
the building shall be enclosed at the top with construction of
the same fire-resistance rating as the topmost floor penetrated
by the shaft, but not less than the fire-resistance rating
required for the shaft enclosure.
 
So when I read that steveray I conclude that a room that is a control area can not terminate at a horizontal assembly. A control area room isn't a shaft and it isn't a exit stair enclosure. Would you agree?
 
nealderidder said:
So when I read that steveray I conclude that a room that is a control area can not terminate at a horizontal assembly. A control area room isn't a shaft and it isn't a exit stair enclosure. Would you agree?
Click to expand...

It looks that way...As much sense as it doesn't make.....The problem is(existing building)when you put the rated ceiling in the enclosure and the walls still have to go up, you create a concealed space with no access to probably a bunch of mechanicals that also need to be protected as rated penetrations to what real gain....?
 
steveray said:
It looks that way...As much sense as it doesn't make.....The problem is(existing building)when you put the rated ceiling in the enclosure and the walls still have to go up, you create a concealed space with no access to probably a bunch of mechanicals that also need to be protected as rated penetrations to what real gain....?
Click to expand...

Exactly.
 
cda said:
If doing for chemical control, can they put a one hour ceiling on it??
Click to expand...
There are no exceptions for control areas. The exceptions for shafts and exit enclosures pertain to those elements when the shaft or exit enclosure does not extend all the way through a story.
 
RLGA said:
There are no exceptions for control areas. The exceptions for shafts and exit enclosures pertain to those elements when the shaft or exit enclosure does not extend all the way through a story.
Click to expand...


I can’t build a one hour box??

With a one hour top.

Works for corridors, works for apartment units, works for other


Just wondering


A building by itself is a control area.
 
cda said:
I can’t build a one hour box??

With a one hour top.

Works for corridors, works for apartment units, works for other


Just wondering


A building by itself is a control area.
Click to expand...
Fire-rated corridors and dwelling/sleeping unit separations are constructed using fire partitions, which do not have a requirement to extend through concealed spaces and are expressly permitted to terminate at the underside of a horizontal assembly, provided it has an equal or greater fire-resistance rating than the fire barrier.
 
Ok been awhile since I have done a control area.

Just strange you can store 100% more of some stuff in a metal cabinet, but not build a standalone one hour room, and store the same stuff, with out getting the entire building involved
 
cda said:
Ok been awhile since I have done a control area.

Just strange you can store 100% more of some stuff in a metal cabinet, but not build a standalone one hour room, and store the same stuff, with out getting the entire building involved
Click to expand...
You can build a standalone room for a control area, but the walls, which are required to be fire barriers, must extend through concealed spaces in the floor/ceiling or roof/ceiling assembly, even if the ceiling surface is part of the horizontal assembly.
 
RLGA said:
You can build a standalone room for a control area, but the walls, which are required to be fire barriers, must extend through concealed spaces in the floor/ceiling or roof/ceiling assembly, even if the ceiling surface is part of the horizontal assembly.
Click to expand...


If I have a single story warehouse

Can I build a stand alone one hour room, without taking the walls to the deck??
 
cda said:
If I have a single story warehouse

Can I build a stand alone one hour room, without taking the walls to the deck??
Click to expand...
If the roof/ceiling assembly is very high above the floor surface, then you probably could build a lid over just the control area; thus, there is no concealed space that is open to other areas of the building.
 
RLGA said:
If the roof/ceiling assembly is very high above the floor surface, then you probably could build a lid over just the control area; thus, there is no concealed space that is open to other areas of the building.
Click to expand...


Thank you

I finally asked the right question.

Normally in the past I have only dealt with one story warehouse type buildings.
 
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