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SECTION 508 MIXED USE AND OCCUPANCY

508.1 General.
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 the applicable provisions of Section 508.2, 508.3 or 508.4, 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 and H-3 occupancies shall be located in a separate and detached building or structure.
3. Uses within live/work units, complying with Section 419, are not considered separate occupancies.
508.2 Accessory occupancies. Accessory occupancies are those occupancies that are ancillary to the main occupancy of the building or portion thereof. Accessory occupancies shall comply with the provisions of Sections 508.2.1 through 508.2.5.3.

508.2.1 Area limitations. Aggregate accessory occupancies shall not occupy more than 10 percent of the building area of the story in which they are located and shall not exceed the tabular values in Table 503, without building area increases in accordance with Section 506 for such accessory occupancies.
508.2.2 Occupancy classification. Accessory occupancies shall be individually classified in accordance with Section 302.1. The requirements of this code shall apply to each portion of the building based on the occupancy classification of that space.
508.2.3 Allowable building area and height. The allowable building area and height of the building shall be based on the allowable building area and height for the main occupancy in accordance with Section 503.1. The height of each accessory occupancy shall not exceed the tabular values in Table 503, without increases in accordance with Section 504 for such accessory occupancies. The building area of the accessory occupancies shall be in accordance with Section 508.2.1.
508.2.4 Separation of occupancies. No separation is required between accessory occupancies and the main occupancy.

Exceptions:
1. Group H-2, H-3, H-4, H-5, I-2, I2.1, I-3 and L occupancies shall be separated from all other occupancies in accordance with Section 508.4.
2. Incidental accessory occupancies required to be separated or protected by Section 508.2.5.
3. Group R-1, R-2, R-2.1 and R-3 dwelling units and sleeping units shall be separated from other dwelling or sleeping units and from accessory occupancies contiguous to them in accordance with the requirements of Section 420.
508.2.5 Separation of incidental accessory occupancies. The incidental accessory occupancies listed in Table 508.2.5 shall be separated from the remainder of the building or equipped with an automatic fire-extinguishing system, or both, in accordance with Table 508.2.5.

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

TABLE 508.2.5 INCIDENTAL ACCESSORY OCCUPANCIES


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 room 1 hour or provide automatic sprinkler systema
Hydrogen cutoff rooms, not classified as Group H 1 hour in Group B, F, M, S and U occupancies; 2 hours 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 a Group I-2 and I-2.1 occupancy 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 quantities not exceeding the maximum allowable quantity 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 electrolyte capacity of more than 50 gallons, or a lithium-ion capacity of 1,000 pounds used for facility standby power, emergency power or uninterrupted power supplies 1 hour in Group B, F, M, S and U occupancies; 2 hours in Group A, E, I and R occupancies.a
Rooms containing fire pumps in no high-rise buildings 2 hours; or 1 hour and provide automatic sprinkler system throughout the building
Rooms containing fire pumps in high-rise buildings 2 hours

For SI: 1 square foot = 0.0929 m2, 1 pound per square inch (psi) = 6.9 kPa, 1 British thermal unit (Btu) 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.
508.2.5.1 Fire-resistance-rated separation. Where Table 508.2.5 specifies a fire-resistance-rated separation, the incidental accessory occupancies shall be separated from the remainder of the building by a fire barrier constructed in accordance with Section 707 or a horizontal assembly constructed in accordance with Section 712, or both. Construction supporting 1-hour fire-resistance-rated fire barriers or horizontal assemblies used for incidental accessory occupancy separations in buildings of Type IIB, IIIB and VB construction are not required to be fire-resistance rated unless required by other sections of this code.
508.2.5.2 Nonfire-resistance-rated separation and protection. Where Table 508.2.5 permits an automatic fire-extinguishing system without a fire barrier, the incidental accessory occupancies shall be separated from the remainder of the building by construction capable of resisting the passage of smoke. The walls shall extend from the top of the foundation or floor assembly below to the underside of the ceiling that is a component of a fire-resistance-rated floor assembly or roof assembly above or to the underside of the floor or roof sheathing, deck or slab above. Doors shall be self- or automatic- closing upon detection of smoke in accordance with Section 715.4.8.3. Doors shall not have air transfer openings and shall not be undercut in excess of the clearance permitted in accordance with NFPA 80. Walls surrounding the incidental accessory occupancy shall not have air transfer openings unless provided with smoke dampers in accordance with Section 711.7.
508.2.5.3 Protection. Except as specified in Table 508.2.5 for certain incidental accessory occupancies, where an automatic fire-extinguishing system or an automatic sprinkler system is provided in accordance with Table 508.2.5, only the space occupied by the incidental accessory occupancy need be equipped with such a system.
508.3 Nonseparated occupancies. Buildings or portions of buildings that comply with the provisions of this section shall be considered as nonseparated occupancies.

508.3.1 Occupancy classification. Nonseparated occupancies shall be individually classified in accordance with Section 302.1. The requirements of this code 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 building or portion thereof in which the nonseparated occupancies are located.
508.3.2 Allowable building area and height. The allowable building 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.
508.3.3 Separation. No separation is required between nonseparated occupancies.

Exceptions:
1. Group H-2, H-3, H-4, H-5, I-2, I-2.1, I-3 and L occupancies shall be separated from all other occupancies in accordance with Section 508.4.
2. Group R-1, R-2, R-2.1 and R-3 dwelling units and sleeping units shall be separated from other dwelling or sleeping units and from other occupancies contiguous to them in accordance with the requirements of Section 420.
508.4 Separated occupancies. Buildings or portions of buildings that comply with the provisions of this section shall be considered as separated occupancies.

TABLE 508.4 REQUIRED SEPARATION OF OCCUPANCIES (HOURS)


OCCUPANCY
Ad, E
I-4, R-2.1
I-2, I-2.1
I-3
R-1, R-2,
R-3, R-3.1,
R-4
F-2, S-2b, U
B, F-1g, M, S-1
L
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
S
NS
S
NS
S
NS
Ad, E
N
N
2
2
2
NP
2
NP
1
2
N
1
1
2
2
NP
NP
NP
3
4
2
3a
I-4,R-2.1
-
-
1e
NP
2
NP
2
NP
1
NP
2
2
2f
2
2
NP
NP
NP
4
NP
4
NP
I-2,I-2.1
-
-
-
-
N
NP
2
NP
2
NP
2
NP
2f
NP
2
NP
NP
NP
4
NP
4
NP
I-3
-
-
-
-
-
-
N
NP
2
NP
2
2
2
2
2
NP
NP
NP
4
NP
4
NP
R-1, R-2, R-3, R-3.1, R-4
               
N
N
1c
2c
1
2
4
NP
NP
NP
3
NP
2
NP
F-2, S-2b, U
-
-
-
-
-
-
-
-
   
N
N
1
2
1
NP
NP
NP
3
4
2
3a
B, F-1, M, S-1
-
-
-
-
-
-
-
-
   
-
-
N
N
1
NP
NP
NP
2
3
1
2a
L
                           
1
NP
NP
NP
2
NP
1
NP
H-1
-
-
-
-
-
-
-
-
   
-
-
-
-
   
N
NP
NP
NP
NP
NP
H-2
-
-
-
-
-
-
-
-
   
-
-
-
-
   
-
-
N
NP
1
NP
H-3, H-4, H-5
-
-
-
-
-
-
-
-
   
-
-
-
-
   
-
-
-
-
1e, f
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 903.2.5.2.

b. The required separation from areas used only for private or pleasure vehicles shall be reduced by 1 hour but to not less than 1 hour.

c. See Section 406.1.4.

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

e. Separation is not required between occupancies of the same classification.

f. For H-5 occupancies, see Section 415.8.2.2.

g. [SFM] Group I and F1 occupancies and Group R-2.1 and F-1 occupancies shall have a 3-hour separation.




508.4.1 Occupancy classification. Separated occupancies shall be individually classified in accordance with Section 302.1. Each separated space shall comply with this code based on the occupancy classification of that portion of the building.
508.4.2 Allowable building area. In each story, the building area shall be such that the sum of the ratios of the actual building area of each separated occupancy divided by the allowable building area of each separated occupancy shall not exceed 1.
508.4.3 Allowable height. Each separated occupancy shall comply with the building height limitations based on the type of construction of the building in accordance with Section 503.1.

Exception:
Special provisions permitted by Section 509.
508.4.4 Separation. Individual occupancies shall be separated from adjacent occupancies in accordance with Table 508.4.
508.4.4.1 Construction. Required separations shall be fire barriers constructed in accordance with Section 707 or horizontal assemblies constructed in accordance with Section 712, or both, so as to completely separate adjacent occupancies.