# Exit Enclosure Termination



## duckbill (Mar 23, 2010)

IBC 2009, Section 1022, requires exit enclosures to be constructed as Fire Barriers per Section 707.  Section 707.5, Continuity, requires the fire barriers to extend from the top of the floor/ceiling assembly below to the underside of the floor or roof sheathing above.

I have a three story apartment building (R-2) of VB construction, framed walls and wood trusses.  I am requiring the exit enclosure (interior) to extend to the roof sheathing as required by 707.5.  My reasoning is that if the exit enclosure were allowed to terminate at a top enclosure at the bottom of the trusses, the exit enclosure section would have sent you to Section 708 for shaft construction instead of 707 for fire barrier construction.  Both sections contain the same requirements for openings, penetrations, joints, ducts, etc. except the shaft is permitted to terminate at a top enclosure and the exit enclosure does not.

What is your interp of this section?  If you allow an exit enclosure to terminate at a rated top enclosure, how do you make the jump from section 707 to 708?


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## Coug Dad (Mar 23, 2010)

Re: Exit Enclosure Termination

Technically, the fire barrier wall should extend to the underside of the deck.  This is not always practiable.  I have seen the top of the stair enclosure as a cap.  However, the cap needs to be supported by the fire barrier walls and not from the trusses above.


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## High Desert (Mar 23, 2010)

Re: Exit Enclosure Termination

Section 1022 says you can use both fire bariiers or horizontal assemblies. So you can constructed them with a one-hour lid.

1022.1 Enclosures required. Interior exit stairways and interior exit ramps shall be enclosed with *fire barriers constructed in accordance with Section 707 or horizontal assemblies constructed in accordance with Section 712, or both*.


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## Coug Dad (Mar 23, 2010)

Re: Exit Enclosure Termination

High Desert's code references are slightly off, (maybe it is an Oregon thing) but a fire resistive rated lid would techinically not be either a floor or roof as specified in Section 711.  However,  I have seen lids frequently used and feel it is a reasonable solution if the lid is supported from the exit enclosure fire barrier walls.


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## High Desert (Mar 23, 2010)

Re: Exit Enclosure Termination

My code reference is straight out of the 2009 IBC. It's not an Oregon thing.


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## Coug Dad (Mar 23, 2010)

Re: Exit Enclosure Termination

My bad!    I was looking at the 2006


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## duckbill (Mar 23, 2010)

Re: Exit Enclosure Termination

It seems if the code was okay with a "lid", the exit enclosure section would have sent you to SHAFT ENCLOSURES in 708 where "lids" are permitted instead of the FIRE BARRIER section which does not contain that exception.  Coug Dad brings up a good point, "a fire resistive rated lid would techinically not be either a floor or roof", which is required for the continuity of fire barrier construction of an exit enclosure.

High Desert also has a good point, "Interior exit stairways and interior exit ramps shall be enclosed with fire barriers constructed in accordance with Section 707 or horizontal assemblies constructed in accordance with Section 712, or both"; however, placing a horizontal assembly on top of the exit enclosure will not meet the termination requirements of the fire barrier walls.


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## Coug Dad (Mar 23, 2010)

Re: Exit Enclosure Termination

Shafts and exit enclosures are both created by fire barriers, but the lid exception is explicit for shafts, but not for exit enclosures.


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## mtlogcabin (Mar 23, 2010)

Re: Exit Enclosure Termination

1020.1 Enclosures required.

Interior exit stairways and interior exit ramps shall be enclosed with fire barriers constructed in accordance with Section 706

I believe exception 2 is pretty clear the fire barrier for a vertical exit enclosure (shaft) does not have to terminate at the roof deck.

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. Hollow vertical spaces within a fire barrier shall be fireblocked in accordance with Section 717.2 at every floor level.

Exceptions:

1.	The maximum required fire-resistance rating for assemblies supporting fire barriers separating tank storage as provided for in Section 415.6.2.1 shall be 2 hours, but not less than required by Table 601 for the building construction type.

2.	Shaft enclosures shall be permitted to terminate at a top enclosure complying with Section 707.12.


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## High Desert (Mar 23, 2010)

Re: Exit Enclosure Termination

Both the 2006 and the 2009 IBC state, "Interior exit stairways and interior exit ramps shall be enclosed with *fire barriers constructed in accordance with Section 706 (2006) 707 (2009) or horizontal assemblies constructed in accordance with Section 711 (2006) 712 (2009), or both*."

A one-hour rated horizontal assembly can be used in a vertical exit enclosure. If it can't, then please tell me where you can use a horizantal assembly in a vertical exit enclosure, as the code clearly allows.

So you can terminate the fire barriers at an unrated roof deck, but you cannot terminate them at a one-hour fire-resistive ceiling?


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## Coug Dad (Mar 23, 2010)

Re: Exit Enclosure Termination

High Desert

I agree with you,  but Section 712 (2009) for horizontal assemblies is for roofs and floors.  Some AHJ's have not considered a lid as a floor or a roof and not allowed a lid.  I believe a lid is a reasonable approach if it is supported by the enclosure walls.


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## duckbill (Mar 24, 2010)

Re: Exit Enclosure Termination

High Desert

The rated horizontal assembly would be used when the stair tower does not follow a straight vertical line.  An area of refuge for example may expand the stair tower horizontally on certain floors.  The horizontal element of the exit enclosure would have to be constructed as a rated horizontal assembly.

Mtlogcabin

The exception is for shaft walls to terminate at a top enclosure and not fire barrier walls.  If exit enclosures were intended to be built as a shaft, Section 1022, Exit Enclosures, would have directed us to Section 708, Shaft Enclosures.  Shafts must be constructed as fire barriers and the continuity section would then permit the top enclosure termination.


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## texasbo (Mar 24, 2010)

Re: Exit Enclosure Termination

My opinion would be that the allowance for horizontal construction does not limit where it can occur. 708.5 and  1022.1 both allow vertical, horizontal or both, without specifying particular applications. I see your point where the code is somewhat circuitous, but I would approve the horizontal assembly.


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## duckbill (Mar 24, 2010)

Re: Exit Enclosure Termination

Same building...three story apartment (R-2) of VB construction, framed walls and wood trusses, related scenario.

This apartment building has a refuse chute to all three floors.  The refuse chute must be constructed as a shaft using fire barrier walls.  These walls can terminate at a top enclosure under the wood trusses.  Access to this refuse chute must be through a room enclosed by fire barriers per Section 708.13.3 (IBC 2009).  The fire barrier walls enclosing the access room on the third floor are required to terminate at the roof deck.  Would you also allow this room to terminate at the bottom of the truss by calling this room a shaft and terminating it at a top enclosure like you are doing for the exit enclosure?


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## Coug Dad (Mar 24, 2010)

Re: Exit Enclosure Termination

I believe the trash chute has to vent to the outside through the roof.


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## mtlogcabin (Mar 24, 2010)

Re: Exit Enclosure Termination



> If exit enclosures were intended to be built as a shaft, Section 1022, Exit Enclosures, would have directed us to Section 708, Shaft Enclosures


Then why does 707.1 (2006 edition) for shaft construction send us back to 706 just as 1020.1 (2006 edition) does :?:  Every class I have attended the instructors have said a verticle exit enclosure is a shaft. I admit this is an interesting post and it is challenging my previous thoughts

707.1 General.

The provisions of this section shall apply to vertical shafts where such shafts are required to protect openings and penetrations through floor/ceiling and roof/ceiling assemblies. Shaft enclosures shall be constructed as fire barriers in accordance with Section 706


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## Plans Approver (Mar 24, 2010)

Re: Exit Enclosure Termination

I know it's not code, but, the 2006 Commentary to 706.1 "_...Fire barriers limit the number of openings. Fire barrier wall assemblies must be continuous from the top of a fire-resistance-rated floor/ceiling assembly to the bottom of the floor or roof slab/deck above. Unlike fire partitions, addressed in Section 708, __*there are no circumstances under which a fire barrier wall is permitted to terminate at a ceiling*__._"

I was trumped by the state several years ago for not allowing a lid on an interior stair enclosure when the "Shaft" section was titled "Shaft and Exit Enclosures". 2000 or 2003 IBC, I think. Maybe '96 BOCA. (Gettin old  :cry: )


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## Paul Sweet (Mar 24, 2010)

Re: Exit Enclosure Termination

The cap has to be constructed as a rated floor-ceiling assembly and be supported by the shaft walls, or the same construction that supports the shaft.  It doesn't matter whether the "floor" that the cap forms is usable or not.

You can't just slap rated gyp board on the bottom of the roof trusses and call it a cap.


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## duckbill (Mar 25, 2010)

Re: Exit Enclosure Termination

Mtlogcabin

Your question, "Then why does 707.1 (2006 edition) for shaft construction send us back to 706 just as 1020.1 (2006 edition) does?"

IBC 2006, Section 1020.1, sends you to 706, Fire Barriers, for construction of an exit enclosure.

IBC 2006, Section 707.1, sends you to 706, Fire Barriers, for construction of a shaft enclosure.  As a shaft, you can now use the exception to terminate at a lid.

Plans Approver

This is also not code, but in the new 2009 IBC Handbook, the section on exit enclosures never mentions the word "shaft" except to say that exit enclosures are regulated in a manner consistent with shaft enclosures for fire rating.  It appears the author is also treating exit enclosures and shaft enclosures as two different animals.


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