Does a fire wall create separate buildings when calculating combined fire areas?

[thriftwoo]

This change was made to the 2018 IBC, Section 503.1:

[…] For the purposes of determining area limitations, height limitations and type of construction, each portion of a building separated by one or more fire walls complying with Section 706 shall be considered to be a separate building.

Example: Three attached F-1 tenant spaces on a single property. Each tenant space has a 10,000 sf fire area and is separated from the other F-1 tenants by 3-hour fire walls. In IBC 2015, each tenant space can be evaluated as a separate building for calculating combined fire areas. In this case, sprinklers would not be required per IBC 903.2.3, as no single building has a combined fire area exceeding 24,000sf.

I interpret the literal text of the 2018 IBC change to mean that fire walls now only create separate buildings in regard to height and area limitations and type of construction under chapter 5. In evaluating combined fire areas, you cannot consider the three tenants as separate buildings, regardless of the presence of fire walls. In this example, the combined fire areas would be 30,000 sf, requiring sprinklers throughout all three tenant spaces per IBC 903.2.3.

Digging into the committee action associated with this change (see below), it seems the intent of the change was to reduce duplication of building systems from building officials assuming each “building” on either side of a fire wall requires completely separate systems. It doesn’t appear to be the intent to prevent using fire walls to split up buildings to keep combined fire areas below the areas triggering sprinklers.

G 130-15
503.1, 706.1
2015 International Building Code

Revise as follows:

503.1 General. Unless otherwise specifically modified in Chapter 4 and this chapter, building height, number of stories and building area shall not exceed the limits specified in Sections 504 and 506 based on the type of construction as determined by Section 602 and the occupancies as determined by Section 302 except as modified hereafter. Building height, number of stories and building area provisions shall be applied independently. EachFor the purposes of determining area limitations, height limitations and type of construction, each portion of a building separated by one or more fire walls complying with Section 706 shall be considered to be a separate building.

706.1 General. Each portion of a building separated by one or more fire

Fire walls that comply with the provisions of this section shall be considered a separate buildingconstructed in accordance with Sections 706.2 through 706.11. The extent and location of such fire walls shall provide a complete separation. Where a fire wall separates occupancies that are required to be separated by a fire barrier wall, the most restrictive requirements of each separation shall apply.

Reason: The purpose of this proposal is to clarify the intent of these sections of the Code that the requirement for a fire wall in Sections 503.1 and 706.1 is predicated on the determination of the maximum allowable height and area calculations under Chapter 5. Using these sections of Code to control other building features or elements such as means of egress, building systems or building utilities is not intended or implied by these sections of the Code. However, by inclusion of the first sentence in Section 706.1 some code officials have incorrectly interpreted that language to mean that the portions of the various elements and systems on each side of a fire wall must be completely self-contained. There are no requirements in the I Codes that mandate that the placement of fire walls to create a separate building such that its building features need to be separated from other like building features in adjacent buildings. The scope of Section 706 is to provide the technical requirements for the construction of a fire wall.

The added language in Section 503.1 along with the strikeout and added language in Section 706.1 will clarify application of these two sections.


G 130-15 Committee Action:
Approved as Submitted
Committee Reason: The proposal clearly separates the scoping of fire walls from the design requirements for fire walls. Section 706.1 is the location of the standards for fire walls and is similar other provisions in Chapter 7 which are the 'cook books' for each type of wall and horizontal assemblies. The committee hopes that this will reduce requests for duplication of other systems such as sprinkler systems, electrical systems, etc, in each portion of a structure separated by fire walls. The new text in 503.1 clearly states why fire walls are needed for addressing height and area limitations as well as type of construction.

 

[walker.t]

I don’t see a question in your post, only in the thread title: “Does a fire wall create separate buildings when calculating combined fire areas?”

The answer to that question is “Yes,” per the definition of “Fire Area”:

2018 IBC Partial Definition of Fire Area (emphasis added)
The aggregate floor area enclosed and bounded by fire walls, fire barriers, exterior walls or horizontal assemblies of a building.

[02/09 edit: I should have clarified that this quote to the definition of Fire Area addressed the first part of the question in the thread title (“Does a fire wall create separate buildings…”), then the part below addresses combined fire areas, sorry for any confusion that may have caused.]

Regarding your comment about the combined fire areas of the three F-1 spaces, 903.2.4 Point 3 states that if the combined area of all the Group F-1 fire area exceeds 24,000 s.f. that you need to install sprinklers. It doesn’t mean that fire walls don’t break the building up into smaller “buildings” for purposes of code analysis, it just means in this case the code puts a limit on the total area of all the fire areas. Per the 2021 IBC commentary:

2021 IBC Commentary on 903.2.4 Group F-1 (partial quote)
Therefore, occupancies of Group F-1 must be protected throughout with an automatic sprinkler system if the fire area is in excess of 12,000 square feet; if the total of all fire areas is in excess of 24,000 square feet… This is one of the few locations in the code where the total floor area of the building is aggregated for application of a code requirement.

 

[RLGA]

Per the limitations stipulated in the modification to Section 503.1, condition #3 of Section 903.2.4 would apply to the aggregate of all fire areas within a building, even those buildings separated by fire walls.

 

[steveray]

It doesn’t appear to be the intent to prevent using fire walls to split up buildings to keep combined fire areas below the areas triggering sprinklers.

If they were only fire areas, as Ron says, you are capped at 24,000 max....I don't believe the intent of the change to 503.1 was to require separate buildings to "share" sprinkler requirements...

 

[Paul Sweet]

Condition 3 looks like it applies to multi-story F-1 buildings or where fire barriers define fire areas, not to separate buildings with fire walls between them.

 

[RLGA]

Condition 3 looks like it applies to multi-story F-1 buildings or where fire barriers define fire areas, not to separate buildings with fire walls between them.

It applies to buildings of any number of stories, including basements (i.e., "all floors"). A building separated by fire walls is still a single building for all purposes other than area limitations, height limitations, and type of construction as stipulated by Section 503.1.

 

[thriftwoo]

There was a code change proposal (FS20-24) on the latest code development cycle that looked to address this:
See "FS20-24" on page 42 of this PDF: https://www.iccsafe.org/wp-content/uploads/IBC-Fire-Safety-2024.pdf

It appears to have since been disapproved, with the committee reason: The committee disapproved the proposal based on the fact that the proposal creates unintended consequences. The committee suggested clarifying the requirements, for example, if there is a residential occupancy within a large building. The committee also indicated that the proposal adds unnecessary cost (Vote: 11-0).

The committee reasoning doesn't disagree that this was unintended consequence of the change to 503.1. It seems the disapproval was rather out of a concern that the proposed language to fix it may have other unintended consequences.

 

[steveray]

There was a code change proposal (FS20-24) on the latest code development cycle that looked to address this:
See "FS20-24" on page 42 of this PDF: https://www.iccsafe.org/wp-content/uploads/IBC-Fire-Safety-2024.pdf

It appears to have since been disapproved, with the committee reason: The committee disapproved the proposal based on the fact that the proposal creates unintended consequences. The committee suggested clarifying the requirements, for example, if there is a residential occupancy within a large building. The committee also indicated that the proposal adds unnecessary cost (Vote: 11-0).

The committee reasoning doesn't disagree that this was unintended consequence of the change to 503.1. It seems the disapproval was rather out of a concern that the proposed language to fix it may have other unintended consequences.

Yep...2 wrongs don't make it right.....Too much stuff is getting approved that "ain't right".....

 

[Genduct]

Condition 3 looks like it applies to multi-story F-1 buildings or where fire barriers define fire areas, not to separate buildings with fire walls between them.

Isn't the difference between fire area ( with Fire WALL) and Fire Zone (Fire partition) the fact that the Fire Wall requires that the structure be independent and separate so that it does in fact create 2 independent Buildings?

I alway get confused

 

[Genduct]

It applies to buildings of any number of stories, including basements (i.e., "all floors"). A building separated by fire walls is still a single building for all purposes other than area limitations, height limitations, and type of construction as stipulated by Section 503.1.
View attachment 15125

Isn't the difference between fire area ( with Fire WALL) and Fire Zone (Fire partition) the fact that the Fire Wall requires that the structure be independent and separate so that it does in fact create 2 independent Buildings?

I alway get confused

PS I posted this twice

 

[walker.t]

and Fire Zone (Fire partition)

I don’t think “fire zone” is a term used in the code. The term “fire area” is used regardless of the building elements used to define it:

2021 IBC Definition of “Fire Area” (partial quote, emphasis added.)
The aggregate floor area enclosed and bounded by fire walls, fire barriers, exterior walls or horizontal assemblies of a building.

so that it does in fact create 2 independent Buildings?

2021 IBC Definition of “Fire Wall” (emphasis added)
A fire-resistance-rated wall having protected openings, which restricts the spread of fire and extends continuously from the foundation to or through the roof, with sufficient structural stability under fire conditions to allow collapse of construction on either side without collapse of the wall.

Depends how you define “independent building”; “independent building” does not mean that there has to be a gap between the buildings. Here are three things that readily come to mind that show that the “buildings” on each side of the fire wall are not independent buildings:

1. Continuous floor slab under the fire wall.
2. Roof structure and roofing material of both buildings tied to the fire wall.
3. Common utility service serving both sides of the fire wall.

In this case, if you removed the fire wall, the roofs of both buildings would collapse because the fire wall is supporting them. But the key is that if the building on one side of the fire wall collapsed, the fire wall would remain intact. It is permissible that the fire wall be tied to the roof structures adjacent to it for lateral support but the connections will be designed to allow the roofs to break away from the fire wall without pulling down the fire wall.

Fire partitions do not have the same requirement for remaining in place if there is collapse of the structure on one side of the wall.

 

[Genduct]

I don’t think “fire zone” is a term used in the code. The term “fire area” is used regardless of the building elements used to define it:




Depends how you define “independent building”; “independent building” does not mean that there has to be a gap between the buildings. Here are three things that readily come to mind that show that the “buildings” on each side of the fire wall are not independent buildings:

1. Continuous floor slab under the fire wall.
2. Roof structure and roofing material of both buildings tied to the fire wall.
3. Common utility service serving both sides of the fire wall.

In this case, if you removed the fire wall, the roofs of both buildings would collapse because the fire wall is supporting them. But the key is that if the building on one side of the fire wall collapsed, the fire wall would remain intact. It is permissible that the fire wall be tied to the roof structures adjacent to it for lateral support but the connections will be designed to allow the roofs to break away from the fire wall without pulling down the fire wall.

Fire partitions do not have the same requirement for remaining in place if there is collapse of the structure on one side of the wall.

Point taken, of course our standard type 3 rowhome has that party wall with parapet that would remain standing if there was a fire in one side, was thinking of ssituation where you are not sharing the same column with a girt on both sides supporting a roof structure and rated assembly Maybe an independent masonry wall and parapet with a column on both sides,

I think the fire zone term is a NFPA reference like AHJ