Firewall required when dividing construction types?

[Honus Wagner]

Hi,

We are designing an R-2 building which has 3-,4- and 5-story wood-framed portions over a podium. We had initially planned for the entire wood-framed portion to be Type III-B. However, FRTW, which is required for the exterior bearing walls in Type III-B, is crazy expensive right now so we are looking to split the building into two chunks: a 5-Story Type III-B chunk and a 3- and 4-story Type V-A chunk.

Is a firewall required where we are changing construction types?

Thanks Everyone.

 

[classicT]

In order to change construction type, the wood framed portions would have to be separate buildings.

A fire wall would be one method of doing this. Could also do exterior walls where the framed buildings are not connected.

You can also refer to the following.

510.9 Multiple Buildings Above a Horizontal Assembly
Where two or more buildings are provided above the horizontal assembly separating a Group S-2 parking garage or building below from the buildings above in accordance with the special provisions in Section 510.2, 510.3 or 510.8, the buildings above the horizontal assembly shall be regarded as separate and distinct buildings from each other and shall comply with all other provisions of this code as applicable to each separate and distinct building.

 

[Honus Wagner]

In order to change construction type, the wood framed portions would have to be separate buildings.

A fire wall would be one method of doing this. Could also do exterior walls where the framed buildings are not connected.

You can also refer to the following.

510.9 Multiple Buildings Above a Horizontal Assembly
Where two or more buildings are provided above the horizontal assembly separating a Group S-2 parking garage or building below from the buildings above in accordance with the special provisions in Section 510.2, 510.3 or 510.8, the buildings above the horizontal assembly shall be regarded as separate and distinct buildings from each other and shall comply with all other provisions of this code as applicable to each separate and distinct building.

Thanks for your response to this.

It's kind of a complex building, so I've attached the diagram below to try to help explain.

Am I correct that we need to have a firewall somewhere between the III-B and V-A construction? Or, are we able to just use table 602 and use the fire separation distance, and possibly an imaginary property line, to determine the rating of the walls?

Thanks!

 

[classicT]

Thanks for your response to this.

It's kind of a complex building, so I've attached the diagram below to try to help explain.

Am I correct that we need to have a firewall somewhere between the III-B and V-A construction? Or, are we able to just use table 602 and use the fire separation distance, and possibly an imaginary property line, to determine the rating of the walls?

Thanks!

I would follow the path of using an imaginary lot line between the two buildings, and then comply with the fire separation requirements of Table 602.

 

[steveray]

What is the construction type of the egress balcony/ stairs? And can you structurally separate them?

 

[JPohling]

The redesign of this building will cost more than the FRTW wood.

 

[Honus Wagner]

I would follow the path of using an imaginary lot line between the two buildings, and then comply with the fire separation requirements of Table 602.

Thanks for the response - we asked one of the code officials from the AHJ and they also said to refer to table 602. As long as this is an acceptable solution, we would end up with a few 1-hr walls, but that would be preferable to 3-hr firewalls...

I was under the impression that firewalls were required whenever two separate types of construction are abutting each other in the same building.

 

[classicT]

Thanks for the response - we asked one of the code officials from the AHJ and they also said to refer to table 602. As long as this is an acceptable solution, we would end up with a few 1-hr walls, but that would be preferable to 3-hr firewalls...

I was under the impression that firewalls were required whenever two separate types of construction are abutting each other in the same building.

If they are the same building, then uniform construction type is required.

But what you are proposing is actually 3 separate buildings. The separation can be created by either a fire wall/horizontal assembly, or by lot line with FSD.

1. The Type I/II podium building
2. The Type III-B 5-story
3. The Type V-A 4 story

 

[Honus Wagner]

What is the construction type of the egress balcony/ stairs? And can you structurally separate them?

The egress balcony structure is steel framed with a composite deck, so it could be classified as II-B if that would help us out. However, that's where I am unclear on the firewall requirements. If we have to have a firewall between the egress balcony structure and the Type III-B Type V-A construction because we are now classifying the balcony as a different type of construction, it's a problem, but if we don't have need a firewall there it could be a potential option to classify the egress balcony structure as II-B.

The egress balcony structure is separate from the III-B and V-A construction from a gravity load standpoint, but they do tie together for lateral support.

 

[Honus Wagner]

If they are the same building, then uniform construction type is required.

But what you are proposing is actually 3 separate buildings. The separation can be created by either a fire wall/horizontal assembly, or by lot line with FSD.

1. The Type I/II podium building
2. The Type III-B 5-story
3. The Type V-A 4 story

I see what you are saying, and I understand using an imaginary lot line and FSD for the III-B and V-A "buildings", but it almost seems like it is four buildings:

1. The Type I/II podium building
2. The Type III-B 5-story
3. The Type V-A 4 story
4. The egress balcony structure, which could be classified as II-B. If this is a separate building, then we would need imaginary lot lines between it and the other types of construction.

But it is probably best to classify the breezeway structure as whatever construction type it is serving, to keep it as simple as possible.

 

[classicT]

I see what you are saying, and I understand using an imaginary lot line and FSD for the III-B and V-A "buildings", but it almost seems like it is four buildings:

1. The Type I/II podium building
2. The Type III-B 5-story
3. The Type V-A 4 story
4. The egress balcony structure, which could be classified as II-B. If this is a separate building, then we would need imaginary lot lines between it and the other types of construction.

But it is probably best to classify the breezeway structure as whatever construction type it is serving, to keep it as simple as possible.

You are creating too many different buildings. Keep in mind that when using an imaginary lot line, you are also limited on openings. There less than 3-ft of FSD, openings are not even permitted typically.

Having a better understanding of the project, I think that you really only have two buildings (the podium and everything above).

A fire wall may work, but be mindful that a fire wall has to be structurally independent. Meaning collapse on either side of the wall without damaging the fire wall or the construction on the other side is required. Openings in that fire wall must also be protected, or are in some cases depending on the fire wall construction, not even permitted (i.e. GA Area Separation Walls).