ICC Subscriptions
 
SECTION 508 MIXED USE AND OCCUPANCY

508.1 General.


Where a building or portion thereof contains two or more occupancies or uses, the building or portion thereof shall comply with the applicable provisions of this section.

508.2 Incidental uses.


Incidental use areas shall comply with the provisions of this section.

Exception:
Incidental use areas within and serving a dwelling unit are not required to comply with this section.

508.2.1 Occupancy classification.

An incidental use area shall be classified in accordance with the occupancy of that portion of the building in which it is located or the building shall be classified as a mixed occupancy and shall comply with Section 508.3.
508.2.2 Separation.

Incidental use areas shall be separated or protected, or both, in accordance with Table 508.2.
508.2.2.1 Construction.

Where Table 508.2 requires a fire-resistance-rated separation, the incidental use area shall be separated from the remainder of the building by a fire barrier constructed in accordance with Section 706 or a horizontal assembly constructed in accordance with Section 711, or both. Where Table 508.2 permits an automatic fire-extinguishing system without a fire barrier, the incidental use area shall be separated from the remainder of the building by construction capable of resisting the passage of smoke. The partitions shall extend from the floor to the underside of the fire-resistance-rated floor/ceiling assembly or fire-resistance-rated roof/ceiling assembly above or to the underside of the floor or roof sheathing, or sub deck above. Doors shall be self- or automatic closing upon detection of smoke in accordance with Section 715.4.7.3. Doors shall not have air transfer openings and shall not be undercut in excess of the clearance permitted in accordance with NFPA 80.
508.2.3 Protection.

Where an automatic fire-extinguishing system or an automatic sprinkler system is provided in accordance with Table 508.2, only the incidental use areas need be equipped with such a system.

TABLE 508.2 INCIDENTAL USE AREAS


ROOM OR AREA
SEPARATION AND/OR
PROTECTION

Furnace room where any piece of equipment is over 400,000 Btu per hour input
1 hour or provide automatic fire-extinguishing systema
Rooms with boilers where the largest piece of equipment is over 15 psi and 10 horsepower
1 hour or provide automatic fire-extinguishing systema 
Refrigerant machinery rooms
1 hour or provide automatic sprinkler systema
Parking garage (Section 406.2)
2 hours; or 1 hour and provide automatic fire-extinguishing system
Hydrogen cut-off rooms, not classified as Group H
1-hour in Group B, F, M, S and U occupancies. 2-hour in Group A, E, I and R occupancies.
Incinerator rooms
2 hours and automatic sprinkler system
Paint shops, not classified as Group H, located in occupancies other than Group F
2 hours; or 1 hour and provide automatic fire-extinguishing system
Laboratories and vocational shops, not classified as Group H, located in Group I-2 and I-2.1 occupancies
1 hour or provide automatic fire-extinguishing systema
Rooms or areas with special hazards such as laboratories, vocational shops and other such areas not classified as Group H, located in Group E occupancies where hazardous materials in exempt amounts are used or stored [SFM]
1 hour
Laundry rooms over 100 square feet
1 hour or provide automatic fire-extinguishing systema 
Storage rooms over 100 square feet
1 hour or provide automatic fire-extinguishing systema
Group I-2 and I-2.1 waste and linen collection rooms
1 houra
Waste and linen collection rooms over 100 square feet
1 hour or provide automatic fire-extinguishing systema
Stationary storage battery systems having a liquid capacity of more than 100 gallons used for facility standby power, emergency power or uninterrupted power supplies
1-hour in Group B, F, M, S and U occupancies. 2-hour in Group A, E, I and R occupanciesa.


For SI:   1 square foot = 0.0929m2, 1 pound per square inch = 6.9 kPa,
1 British thermal unit per hour = 0.293 watts, 1 horsepower = 746 watts,
1 gallon = 3.785 L.
a.   [SFM] Fire barrier protection and automatic sprinkler protection required throughout the fire area in I-2 and I-2.1 occupancies as indicated.
508.3 Mixed occupancies.

Each portion of a building shall be individually classified in accordance with Section 302.1.

Where a building contains more than one occupancy group, the building or portion thereof shall comply with Sections 508.3.1, 508.3.2, 508.3.3 or a combination of these sections.

Exceptions:


1.   Occupancies separated in accordance with Section 509.
2.   Where required by Table 415.3.2, areas of Group H-1, H-2 or H-3 occupancies shall be located in a separate and detached building or structure.
508.3.1 Accessory occupancies.

Accessory occupancies are those occupancies subsidiary to the main occupancy of the building or portion thereof. Aggregate accessory occupancies shall not occupy more than 10 percent of the area of the story in which they are located and shall not exceed the tabular values in Table 503, without height and area increases in accordance with Sections 504 and 506 for such accessory occupancies.

Exceptions:
1.   Accessory assembly areas having a floor area less than 750 square feet (69.7 m2) are not considered separate occupancies.
2.   Assembly areas that are accessory to Group E occupancies are not considered separate occupancies except when applying the assembly occupancy requirements of Chapter 11B.
3.   Accessory religious educational rooms and religious auditoriums with occupant loads of less than 100 are not considered separate occupancies.
508.3.1.1 Occupancy classification.

Accessory occupancies shall be individually classified in accordance with Section 302.1. Code requirements shall apply to each portion of the building based on the occupancy classification of that accessory space, except that the most restrictive applicable provisions of Section 403 and Chapter 9 shall apply to the entire building or portion thereof.
508.3.1.2 Allowable area and height.

The allowable area and height of the building shall be based on the allowable area and height for the main occupancy in accordance with Section 503.1. The height of any accessory occupancy shall not exceed the tabular values in Table 503, without height and area increases in accordance with Sections 504 and 506 for such accessory occupancies.
508.3.1.3 Separation.

No separation is required between accessory occupancies or the main occupancy.

Exception:
Group H-2, H-3, H-4, H-5, I-2, I-2.1 or I-3 occupancies shall be separated from all other occupancies in accordance with Section 508.3.3.
508.3.2 Nonseparated occupancies.

Buildings or portions of buildings that comply with the provisions of this section shall qualify as nonseparated occupancies.
508.3.2.1 Occupancy classification.

Nonseparated occupancies shall be individually classified in accordance with Section 302.1. Code requirements shall apply to each portion of the building based on the occupancy classification of that space except that the most restrictive applicable provisions of Section 403 and Chapter 9 shall apply to the entire building or portion thereof.
508.3.2.2 Allowable area and height.

The allowable area and height of the building or portion thereof shall be based on the most restrictive allowances for the occupancy groups under consideration for the type of construction of the building in accordance with Section 503.1.
508.3.2.3 Separation.

No separation is required between occupancies.

Exception:
Group H-2, H-3, H-4, H-5, I-2, I-2.1, I-3 or L occupancies shall be separated from all other occupancies in accordance with Section 508.3.3.
508.3.3 Separated occupancies.

Buildings or portions of buildings that comply with the provisions of this section shall qualify as separated occupancies.
508.3.3.1 Occupancy classification.

Separated occupancies shall be individually classified in accordance with Section 302.1. Each fire area shall comply with this code based on the occupancy classification of that portion of the building.
508.3.3.2 Allowable area.

In each story, the building area shall be such that the sum of the ratios of the actual floor area of each occupancy divided by the allowable area of each occupancy shall not exceed one.
508.3.3.3 Allowable height.

Each occupancy shall comply with the height limitations based on the type of construction of the building in accordance with Section 503.1. The height, in both feet and stories, of each fire area shall be measured from grade plane. This measurement shall include the height, in both feet and stories, of intervening fire areas.

Exception:
Special provisions permitted by Section 509.
508.3.3.4 Separation.

Individual occupancies shall be separated from adjacent occupancies in accordance with Table 508.3.3.
508.3.3.4.1 Construction.

Required separations shall be fire barriers constructed in accordance with Section 706 or horizontal assemblies constructed in accordance with Section 711, or both, so as to completely separate adjacent occupancies.

TABLE 508.3.3 REQUIRED SEPARATION OF OCCUPANCIES (HOURS)


OCCUPANCY
Ae, E
I
Rd
F-2, S-2c,d,Ud
Bb, F-1, Mb, S-1
H-1
H-2
H-3, H-4, H-5
S
NS
S
NS
S
NS
S
NS
S
NS
S
NS
S
NS
S
NS
Ae, Ee
N
N
2
2
1
2
N
1
1
2
NP
NP
3
4
2
3a
I


N
N
2
NP
2
2
2f
2f
NP
NP
4
NP
4
NP
Rd




N
N
1
2
1
2
NP
NP
3
NP
2
NP
F-2, S-2c,d,Ud






N
N
1
2
NP
NP
3
4
2
3a
Bb, F-1, Mb, S-1








N
N
NP
NP
2
3
1
2a
H-1










N
NP
NP
NP
NP
NP
H-2












N
NP
1
NP
H-3, H-4, H-5














N
NP
L
2
NP
2
NP
4
NP
1
NP
1
NP
NP
NP
2
NP
1
NP


For SI:   1 square foot = 0.0929 m2.

S   =   Buildings equipped throughout with an automatic sprinkler system installed in accordance with Section 903.3.1.1.

NS   =   Buildings not equipped throughout with an automatic sprinkler system installed in accordance with Section 903.3.1.1.

N   =   No separation requirement.

NP   =   Not permitted.
a.   For Group H-5 occupancies, see Section 903.2.4.2.
b.   Occupancy separation need not be provided for storage areas within Groups B and M if the:
   1.   Area is less than 10 percent of the floor area;
   2.   Area is equipped with an automatic fire-extinguishing system and is less than 3,000 square feet; or
   3.   Area is less than 1,000 square feet.

c.   Areas used only for private or pleasure vehicles shall be allowed to reduce separation by 1 hour.

d.   See Section 406.1.4.

e.   Commercial kitchens need not be separated from the restaurant seating areas that they serve.

f.   [SFM] For Group I and F-1 occupancies shall have a 3-hour separation.