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Understanding "Fire Area"

Rchapman

Registered User
Joined
Feb 20, 2020
Messages
14
Location
Sacramento, CA
When applying 903.2.10 Group S-2 Parking Garages (2021 IBC), I find myself having a difficult time grasping "fire area". Chapter 2 defines fire area as: The aggregate floor area enclose and bounded by fire walls, fire barriers, exterior walls or horizontal assemblies of a building. Areas of the building not provided with surrounding walls shall be included in the fire area if such areas are included within the horizontal projection of the roof or floor next above.

My fire protection consultant is under the impression that the fire area is on the square footage of one level of the open parking garage, but I am wondering if that as wrong as soon as the word "aggregate" is used in the definition. Does "aggregate", in this sense, mean all of the square footage of the building and all of the levels/tiers added up? Or is "aggregate" being used to add up all the various spaces and square footages of fire areas that exist on only one floor?
 
Does "aggregate", in this sense, mean all of the square footage of the building and all of the levels/tiers added up?
Yes it means all areas that are not separated by a fire rated assembly in accordance with IBC Table 707.3.10

707.3.10 Fire areas.
The fire barriers, fire walls or horizontal assemblies, or combination thereof, separating a single occupancy into different fire areas shall have a fire-resistance rating of not less than that indicated in Table 707.3.10. The fire barriers, fire walls or horizontal assemblies, or combination thereof, separating fire areas of mixed occupancies shall have a fire-resistance rating of not less than the highest value indicated in Table 707.3.10 for the occupancies under consideration.

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Yes it means all areas that are not separated by a fire rated assembly in accordance with IBC Table 707.3.10

707.3.10 Fire areas.
The fire barriers, fire walls or horizontal assemblies, or combination thereof, separating a single occupancy into different fire areas shall have a fire-resistance rating of not less than that indicated in Table 707.3.10. The fire barriers, fire walls or horizontal assemblies, or combination thereof, separating fire areas of mixed occupancies shall have a fire-resistance rating of not less than the highest value indicated in Table 707.3.10 for the occupancies under consideration.

View attachment 9734
Generic example: How are the separations treated? If I have two areas on one floor, and they are separated via fire rated assemblies, each one being 10,000 SF each, then the "fire area" would be 20,000 SF, because it's the aggregate of the spaces, correct? Isn't that the same as the SF of the floor?

Specific example: In an open parking garage, if each level is separated by a 2 hour rated floor assembly, then each level is a "fire area", and the aggregate will the total SF of those fire areas, which is basically the total SF of the building. (I'm not too sure how "fire areas" apply to open garages, there are a lot of exceptions for the ramps and stairs being non-enclosed, I don't know how finding fire areas in a garage works.)
 
Have you looked into the sq ft and height increases in Ch 4? It'll give you much more info than 5
 
"Specific example: In an open parking garage, if each level is separated by a 2-hour rated floor assembly, then each level is a "fire area", and the aggregate will the total SF of those fire areas, which is basically the total SF of the building. (I'm not too sure how "fire areas" apply to open garages, there are a lot of exceptions for the ramps and stairs being non-enclosed, I don't know how finding fire areas in a garage works.)"

No, each fire area, separated by the appropriate wall/floor, is treated as a separate building.
 
No, each fire area, separated by the appropriate wall/floor, is treated as a separate building.
That is not correct they would be treated as separate fire areas not separate buildings.

There is no limit on the number of fire areas you may have however there are limits on the combined fire areas in certain occupancies which if exceeded will require a fire suppression system

Chapter 9 has maximum combined fire areas for requiring fire suppression systems in specific occupancies.
903.2.1.7 Multiple fire areas.

This one gets missed a lot when trying to avoid sprinklers in "A" occupancies

An automatic sprinkler system shall be provided where multiple fire areas of Group A-1, A-2, A-3 or A-4 occupancies share exit or exit access components and the combined occupant load of theses fire areas is 300 or more.


1. A Group F-1 fire area exceeds 12,000 square feet (1115 m2).

2. A Group F-1 fire area is located more than three stories above grade plane.

3. The combined area of all Group F-1 fire areas on all floors, including any mezzanines, exceeds 24,000 square feet (2230 m2).

1. A Group M fire area exceeds 12,000 square feet (1115 m2).

2. A Group M fire area is located more than three stories above grade plane.

3. The combined area of all Group M fire areas on all floors, including any mezzanines, exceeds 24,000 square feet (2230 m2).
 
Is this an open or enclosed parking garage? If it is an open parking garage, then the fire areas would not come into play because open parking garages are not required to have a fire suppression system installed based on fire areas. Fire suppression would be based on the construction type and the number of tiers
 
Is this an open or enclosed parking garage? If it is an open parking garage, then the fire areas would not come into play because open parking garages are not required to have a fire suppression system installed based on fire areas. Fire suppression would be based on the construction type and the number of tiers
In an open garage, with the new code change, they are required:

[F] 903.2.10 Group S-2 Parking Garages​

An automatic sprinkler system shall be provided throughout buildings classified as parking garages where any of the following conditions exists:
  1. Where the fire area of the enclosed parking garage in accordance with Section 406.6 exceeds 12,000 square feet (1115 m2).
  2. Where the enclosed parking garage in accordance with Section 406.6 is located beneath other groups.
    Exception: Enclosed parking garages located beneath Group R-3 occupancies.
  3. Where the fire area of the open parking garage in accordance with Section 406.5 exceeds 48,000 square feet (4460 m2).
I am having a hard time determining what the fire area of an open parking garage would be. If I have two hour rated floor assemblies, is each floor a separate "fire area"? Why is determining separate fire areas a step I must investigate, because I have to use the aggregate fire area anyways per the definition of "fire area" in Chapter 2, correct? So even if I have two separate fire areas, I'm just adding them together anyways.
 
Short of using elevators for car lifts in your parking garage I do not know how to create a fire area in an open parking garage if you drive from one tier to the next you will only have one fire area
 
Short of using elevators for car lifts in your parking garage I do not know how to create a fire area in an open parking garage if you drive from one tier to the next you will only have one fire area
I've noticed that garages are different enough from buildings, where the building code tends to break down when applying code language for a parking garage. This is one example. The ramps and stairs connecting levels can be non-enclosed via various exceptions in Chapter 10 (ramps connect the levels and obviously cannot be sealed off from levels above/below, otherwise it would impeded vehicle circulation).
I'd imagine that Chapter 9 wouldn't allow me to use those exceptions from Chapter 10 (or maybe it's Chapter 4, 406, I don't remember) in trying to identify each level being it's own fire area when the levels aren't completely separated from each other (via ramps and stairs). Then again, if the fire area is the "aggregate floor area" enclosed by fire barriers, even classifying each level as it's own fire area with said exceptions, I still have to sum up that square footage to determine the fire area, which would almost always exceed the 48,000 SF target.

Thanks for the help.
 
That is not correct they would be treated as separate fire areas not separate buildings.

There is no limit on the number of fire areas you may have however there are limits on the combined fire areas in certain occupancies which if exceeded will require a fire suppression system

Chapter 9 has maximum combined fire areas for requiring fire suppression systems in specific occupancies.
903.2.1.7 Multiple fire areas.

This one gets missed a lot when trying to avoid sprinklers in "A" occupancies

An automatic sprinkler system shall be provided where multiple fire areas of Group A-1, A-2, A-3 or A-4 occupancies share exit or exit access components and the combined occupant load of theses fire areas is 300 or more.


1. A Group F-1 fire area exceeds 12,000 square feet (1115 m2).

2. A Group F-1 fire area is located more than three stories above grade plane.

3. The combined area of all Group F-1 fire areas on all floors, including any mezzanines, exceeds 24,000 square feet (2230 m2).

1. A Group M fire area exceeds 12,000 square feet (1115 m2).

2. A Group M fire area is located more than three stories above grade plane.

3. The combined area of all Group M fire areas on all floors, including any mezzanines, exceeds 24,000 square feet (2230 m2).

That is not correct they would be treated as separate fire areas not separate buildings.

There is no limit on the number of fire areas you may have however there are limits on the combined fire areas in certain occupancies which if exceeded will require a fire suppression system

Chapter 9 has maximum combined fire areas for requiring fire suppression systems in specific occupancies.
903.2.1.7 Multiple fire areas.

This one gets missed a lot when trying to avoid sprinklers in "A" occupancies

An automatic sprinkler system shall be provided where multiple fire areas of Group A-1, A-2, A-3 or A-4 occupancies share exit or exit access components and the combined occupant load of theses fire areas is 300 or more.


1. A Group F-1 fire area exceeds 12,000 square feet (1115 m2).

2. A Group F-1 fire area is located more than three stories above grade plane.

3. The combined area of all Group F-1 fire areas on all floors, including any mezzanines, exceeds 24,000 square feet (2230 m2).

1. A Group M fire area exceeds 12,000 square feet (1115 m2).

2. A Group M fire area is located more than three stories above grade plane.

3. The combined area of all Group M fire areas on all floors, including any mezzanines, exceeds 24,000 square feet (2230 m2).
Understood, I misspoke. What I was trying to say was they can still be considered individually, as long as they are are separated as fire areas.
 
Think of fire areas as shoeboxes, if you can isolate an area by enclosure on six sides by fire rated assemblies required for seperation - you have a shoe box, If any portion of the six sides has a hole or area of unprotections (except fire rated shafts, stairways,etc._) , the fire area includes that area until you have all six sides surrounded by fire rated assemblies or contained in one building.

That is the easiest way I can explain fire areas........
 
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