Fire Area Claculation - Egress Stair Case and Shaft Enclosure

[Saber Elkassas]

Hello Everybody,
I have a question regarding the fire area calculation the fire area calculation as per IBC 2018:

In the fire area calculation, the areas of an enclosed egress stair case protected by fire barrier and services shafts protected also with fire barrier is include or exclude from the fire area calculation?

 

[mtlogcabin]

Yes and no. According to Table 707.3.10 a fire barrier that is constructed to create separate fire areas would be a minimum 2 hour construction. Depending on the number of stories a one hour shaft may be all that is required so you will need to increase the rating of the shafts if they do not meet the requirements of Table 707.3.10.

[BF] FIRE AREA. The aggregate floor area enclosed 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.

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.

TABLE 707.3.10
FIRE-RESISTANCE RATING REQUIREMENTS FOR
FIRE BARRIERS, FIRE WALLS OR HORIZONTAL
ASSEMBLIES BETWEEN FIRE AREAS


OCCUPANCY GROUP FIRE-RESISTANCE RATING
(hours)
H-1, H-2 4
F-1, H-3, S-1 3
A, B, E, F-2, H-4, H-5, I, M, R, S-2 2
U 1

 

[Saber Elkassas]

That's mean if I have for example occupancy E and including a shaft or stair with one hour and the fire barrier is required by Table 707.3.10 to be 2 hrs., so I will have to increase it to 2 hrs. to exclude it and reduce the total fire area, Do I have a right understand or not?

 

[Saber Elkassas]

Please check the below

https://imgur.com/zZIA3gz

 

[RLGA]

That's mean if I have for example occupancy E and including a shaft or stair with one hour and the fire barrier is required by Table 707.3.10 to be 2 hrs., so I will have to increase it to 2 hrs. to exclude it and reduce the total fire area, Do I have a right understand or not?

You are correct. If the stairs have 2-hour shafts, then each of them becomes a separate fire area. Thus, per the drawing in your subsequent post, you would have three fire areas in your building.

 

[Saber Elkassas]

Thank you all, you replies was very helpful.