Fire Barrier 2009 IBC

[jar546]

I have a large building A3 that is using a fire barrier to create separate fire areas in order to circumvent sprinklers. The question on this 2 hour fire barrier is whether or not FRT is needed for 48" to either side where the fire barrier bumps up against the sheathing of the wood framed roof. I can't see where it is required. Am I missing something?

 

[Codegeek]

What type of construction is it?

 

[AegisFPE]

How was the 2-hour rating of the fire barrier selected?

 

[hlfireinspector]

706.5 Continuity.

The supporting construction for fire barriers shall be protected to afford the required fire-resistance rating of the fire barrier supported,

What is supporting your fire barrier?

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[jar546]

VB construction

Spec'd by RDP

 

[Codegeek]

Table 707.3.9 shows 2 hours required. If they can build a 2-hour wall without using FRTW, I don't see where it would be required otherwise.

 

[gbhammer]

The structural ceiling most likely provides lateral bracing for the barrier and 2009 IBC 707.5.1 indicates that: supporting construction for a fire barrier shall be protected to afford the required fire-resistance rating of the fire barrier supported.

 

[jar546]

Table 707.3.9 shows 2 hours required. If they can build a 2-hour wall without using FRTW, I don't see where it would be required otherwise.

I am wondering if I am confusing you the way I worded my post or I don't understand what you are saying. I am not talking about FRT on the fire barrier, I am talking about the intersection of the fire barrier to the underside of the roof sheathing and the fact that the roof sheathing is not FRT for 48" on either side of the fire barrier.

 

[jar546]

706.5 Continuity.

The supporting construction for fire barriers shall be protected to afford the required fire-resistance rating of the fire barrier supported,

​

What is supporting your fire barrier?

​

The fire barrier extends to the underside of the roof sheathing and the roof sheathing is not FRT in that area so a fire can easily jump over the fire barrier. The ceiling of the rooms separated attach to the fire barrier.

 

[steveray]

706.4 Continuity of fire barrier walls.

Fire barrier walls 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. These walls 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 302.1.1 in buildings of Type IIB, IIIB and VB construction. Hollow vertical spaces within the fire barrier wall shall be firestopped at every floor level.

The fire barrier can terminate at the untreated roof deck......GBH does bring up a good question that I had also for FBs....does any structural structural member that passes through have to be rated back to the foundation? In other words, if the roof/ceiling falls down, what good is the wall? I have asked a few dp's the question and they usually change their design......anyone have a definition of "supporting construction"?

 

[Francis Vineyard]

I have a large building A3 that is using a fire barrier to create separate fire areas in order to circumvent sprinklers. The question on this 2 hour fire barrier is whether or not FRT is needed for 48" to either side where the fire barrier bumps up against the sheathing of the wood framed roof. I can't see where it is required. Am I missing something?

No, but where are you getting the 48"? I don't have my books at home today but look at Table 601; 5B has zero rating as opposed to other types of construction with footnotes.

 

[Paul Sweet]

I'm also at home without books, but I believe the 48" FRT sheathing requirement applies when you have a fire WALL terminating against the roof deck, without a parapet.

The supporting constriction requirement applies when you have a fire barrier that is offset at a floor level, or which is on upper stories above an open story. I believe it only applies to gravity loads, and not to lateral bracing.

 

[gbhammer]

I am at home now, but think that the confusion that the 48" rule may be for fire walls not barriers.

 

[hlfireinspector]

I'm also at home without books, but I believe the 48" FRT sheathing requirement applies when you have a fire WALL terminating against the roof deck, without a parapet.

The supporting constriction requirement applies when you have a fire barrier that is offset at a floor level, or which is on upper stories above an open story. I believe it only applies to gravity loads, and not to lateral bracing.

That is the first time I have hear that. Gravity loads only??????????? I always wondered how to meet this requirement. 2 hour wall /2 hour building. This could be a whole new thread.

 

[TJacobs]

I agree with Paul Sweet, but we are not using the 09 yet.

 

[imhotep]

I have a large building A3 that is using a fire barrier to create separate fire areas in order to circumvent sprinklers. The question on this 2 hour fire barrier is whether or not FRT is needed for 48" to either side where the fire barrier bumps up against the sheathing of the wood framed roof. I can't see where it is required. Am I missing something?

I'm not getting it.

A VB building with an A3 occupancy is limited to 6K basic area per Table 503.

Max. increase for frontage per 506.1 could bring the allowable area to 10.5K.

Sprinklers required at 12K per 903.2.1.3.

How might the DP get to 12k without fire walls?

Anyone?

 

[Codegeek]

I am wondering if I am confusing you the way I worded my post or I don't understand what you are saying. I am not talking about FRT on the fire barrier, I am talking about the intersection of the fire barrier to the underside of the roof sheathing and the fact that the roof sheathing is not FRT for 48" on either side of the fire barrier.

I understood. I think there's confusion on the term fire barrier versus fire wall. A fire wall would require the protection with the FRT, but the fire barrier does not.