CBC · California Building Code

Residential Group R — R‑1, R‑2, R‑3, R‑4 distinctions

For homeowners: Group R assigns sleeping uses to different subgroups. R‑1 covers primarily transient lodging (hotels, motels, transient boarding), R‑2 covers primarily permanent multiunit housing (apartments, dorms). The deciding factors are whether occupants are transient or permanent and the number/type of dwelling or sleeping units; special care settings and small licensed care homes have separate rules. See CBC §§ 310.1, 310.2 and 310.3 and consult Section 420 and the AHJ for sprinklers, alarms and care‑facility provisions. file

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Last reviewed: July 5, 2026

What the code requires

The California Building Code (CBC) groups residential occupancies that are used for sleeping under Group R. Section § 310.1 defines Group R as buildings (or parts of buildings) used for sleeping when not classified as Institutional Group I or regulated by the California Residential Code; where the CBC applies, the classification into R‑1 or R‑2 turns largely on whether the occupants are primarily transient or primarily permanent and on the number/type of dwelling or sleeping units (§ 310.1, § 310.2, § 310.3).

Requirements in detail

Scope and application

  • The general definition: Group R covers buildings used for sleeping purposes that are not Group I and are not otherwise regulated by the California Residential Code; Group R occupancies not constructed in accordance with the Residential Code as permitted by other CBC provisions must comply with Section 420 (see § 310.1).

Primary distinguishing criteria (decision dimensions)

The practical decision about whether an occupancy is R‑1 or R‑2 depends on:

  • Whether occupants are primarily transient or primarily permanent; and
  • Whether the space contains sleeping units or more than two dwelling units (the “more than two” threshold is repeated in § 310.2 and § 310.3).

The table below summarizes the decision‑relevant dimensions and where the CBC ties them to the Group R categories.

Decision dimension Typical values / thresholds Typical examples Code reference
Occupant status Primarily transient vs. primarily permanent Hotels, motels, transient boarding houses vs. apartments, long‑term boarding houses § 310.2 (R‑1) and § 310.3 (R‑2)
Number/type of units Sleeping units or more than two dwelling units triggers Group R language Multi‑unit properties, dormitories, apartment houses § 310.1, § 310.2, § 310.3
Boarding/congregate residency threshold Transient boarding/congregate residence noted when >10 occupants Boarding houses (transient) with >10 occupants listed as R‑1 § 310.2 (boarding houses transient >10)
Congregate (nontransient) threshold Congregate living facilities (nontransient) with more than 16 occupants Long‑term group living, dormitories, fraternities § 310.3 (R‑2)
Special subgroups of R‑2 Supervised 24‑hour care settings are subdivided (R‑2.1, R‑2.2) Assisted living / licensed 24‑hour care; CDCR community‑based facilities § 310.3.1 and § 310.3.2 (R‑2.1, R‑2.2)

How the CBC exemplifies R‑1 and R‑2

  • R‑1 examples in the CBC: transient hotels and motels, transient boarding houses and congregate residences (the code explicitly lists hotels and motels and transient boarding/congregate residences under § 310.2).
  • R‑2 examples in the CBC: apartment houses, dormitories, convents, fraternities/sororities, long‑term boarding houses, live/work units and vacation timeshare properties where occupants are primarily permanent (§ 310.3).

Cross‑references you must check when deciding classification

  • If the building or use is governed by the California Residential Code instead of the CBC, the Residential Code controls (see § 310.1).
  • If the occupancy is a supervised 24‑hour care setting, special sub‑classifications and additional rules (sprinklers, smoke compartments, alarm systems) may apply (see § 310.3.1 and § 310.3.2 and the Group R special provisions in Chapter 4 / Section 420). file

Exceptions & special cases

  • Use of the California Residential Code: § 310.1 expressly directs that Group R includes sleeping uses “when not regulated by the California Residential Code.” Where the Residential Code applies instead, follow that code.
  • Group R occupancies that are not constructed per the Residential Code but are covered by CBC provisions are required to comply with Section 420 (special detailed Group R requirements) — see § 310.1 and Section 420 for protections like fire partitions, horizontal assemblies, sprinklers and alarm requirements. file
  • Small residential care/day‑care count: a facility with six or fewer persons receiving custodial care in a dwelling unit is addressed elsewhere in the CBC/HSC and may be classified as Group R‑3 under specified conditions (see § 308.5.4 excerpt). That is an example where the occupant capability and licensing change the occupancy classification.
  • R‑2 subgroups: § 310.3 introduces R‑2.1 (licensed assisted‑living / residential care) and R‑2.2 (CDCR community facility) with specific references to Chapter 4 and Section 420 and to Section 435 for licensed 24‑hour care facilities — these carry additional sprinkler/alarm and smoke compartmenting requirements described in Section 420 and Section 435. file

Common mistakes

  • Treating "hotel" or "motel" as automatically R‑1 or R‑2 without confirming transient vs. nontransient status. The CBC lists both transient and nontransient hotels/motels in the respective sections — use § 310.2 vs § 310.3 to determine classification.
  • Using only the number of units and ignoring occupant intent or duration (transient v. permanent). Both dimensions matter per §§ 310.2–310.3.
  • Overlooking special licensing/health‑care rules that change classification (e.g., small care homes may be R‑3 rather than R‑2, per § 308.5.4).
  • Failing to check whether the California Residential Code applies (if it does, the Residential Code, not CBC Chapter 3, may control) as noted in § 310.1.
  • Ignoring Chapter 4 Group R requirements (Section 420): sprinkler and alarm provisions, fire partitions and horizontal assemblies that apply to Group R occupancies can materially affect design and compliance.

Worked example

Scenario: You are reviewing an existing building that contains three separate apartments (each with its own kitchen and sleeping area). All units are long‑term rentals (residents stay months to years). Which occupancy?

  • The building contains “more than two dwelling units” and occupants are primarily permanent in nature → classify as Residential Group R‑2 under § 310.3. Cite: § 310.3 lists apartment houses and other primarily permanent occupancies as R‑2.

Alternate scenario: A lodging building with rooms rented nightly (hotel) with 20 transient occupants.

  • Because occupants are primarily transient and a hotel is explicitly listed under § 310.2, classify as Residential Group R‑1. Also note: boarding houses (transient) with more than 10 occupants are listed in § 310.2 as R‑1.

Edge numeric example: A boarding house with 9 transient residents — § 310.2 calls out transient boarding houses with more than 10 occupants. The CBC text in § 310.2 explicitly lists boarding houses (transient) with more than 10 occupants; for fewer occupants you must evaluate other applicable provisions (and also check local or Residential Code rules). The plain text for classification at counts ≤10 was not provided in the retrieved excerpts, so consult the full CBC/Residential Code and AHJ for the precise handling. file

Related provisions

  • § 310.1 — Residential Group R general definition (see Chapter 3)
  • § 310.2 — Residential Group R‑1 (transient) examples and scope
  • § 310.3 — Residential Group R‑2 (permanent) examples and scope, including R‑2.1 and R‑2.2 references
  • § 420 (Sections 420.1–420.16) — Special detailed Group R requirements (fire partitions, horizontal separation, sprinklers, alarms, cooking rules, EV charging, licensed‑care provisions)
  • § 308.5.4 — Small custodial care (six or fewer) classification guidance that can move a use into R‑3 in certain situations
  • § 435 — Special provisions for licensed 24‑hour care facilities referenced from Group R special provisions (see the Fire Code appendix and CBC cross references)

Note about R‑3 and R‑4 texts: The explicit CBC text for § 310.4 (Group R‑3) and § 310.5 (Group R‑4) was not included in the files I was given, so I cannot quote or paraphrase those sections authoritatively here. The index references indicate those sections exist (e.g., R‑3 at § 310.4), but you should consult the full CBC text or your AHJ for the official R‑3 and R‑4 definitions and thresholds.

Code references

Grounded in the retrieved California Building Code — click a citation to read the verbatim passage:

  • CBC § 309.3 High relevance — show source text

    309.3 Motor fuel-dispensing facilities. Motor fuel-dispensing facilities shall comply with Section 406.7.

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    OCCUPANCY CLASSIFICATION AND USE

    SECTION 310—RESIDENTIAL GROUP R

    310.1 Residential Group R. Residential Group R includes, among others, the use of a building or structure, or a portion thereof, for sleeping purposes when not classified as an Institutional Group I or when not regulated by the California Residential Code . Group R occupancies not constructed in accordance with the California Residential Code as permitted by Sections 310.4.1 and 310.4.2 shall comply with Section 420.

    310.2 Residential Group R-1. Residential Group R-1 occupancies containing sleeping units or more than two dwelling units where the occupants are primarily transient in nature, including:

    Boarding houses (transient) with more than 10 occupants

    Congregate residences (transient) with more than 10 occupants

    Hotels (transient)

    Motels (transient)

    [HCD 1] Efficiency dwelling units (transient)

    310.3 Residential Group R-2. Residential Group R-2 occupancies containing sleeping units or more than two dwelling units where the occupants are primarily permanent in nature, including:

    Apartment houses

    Large family child care

    Small family child care

    Congregate living facilities (nontransient) with more than 16 occupants

    Boarding houses (nontransient)

    Convents

    Dormitories

    Emergency services living quarters

    Fraternities and sororities

    Monasteries

    Hotels (nontransient)

    Live/work units

    Motels (nontransient)

    Vacation timeshare properties

    [HCD 1] Efficiency dwelling units (transient)

    310.3.1 Residential Group R-2.1. Residential Group R-2.1 occupancies shall include buildings, structures or parts thereof housing clients, on a 24-hour basis, who because of age, mental disability or other reasons, live in a supervised residential environment that provides personal care services.

    This occupancy may contain more than six nonambulatory and/or bedridden clients. (See Section 435 Special Provisions for Licensed 24-Hour Care Facilities in a Group R-2.1, R-3.1 or R-4 Occupancy). This group shall include, but not be limited to, the following:

    Assisted living facilities such as: Residential care facilities, Residential care facilities for the elderly (RCFEs), Adult residential facilities, Congregate living health facilities, Group homes, Residential care facilities for the chronically ill, Congregate living health facilities for the terminally ill.

    Social rehabilitation facilities such as: Halfway houses, Community correctional centers, Community treatment programs, Work furlough programs, Alcoholism or drug abuse recovery or treatment facilities.

    310.3.2 Residential Group R-2.2 (CDCR Only). Residential occupancies operated by CDCR in a community located facility that provides housing and community-based program services for nontransient ambulatory participants in a nonlicensed facility with 24/7 supervision.

  • CBC § 2.1 High relevance — show source text

    SECTION 420—GROUPS R-1, R-2, R-2.1, R-2.2, R-3, R-3.1 AND R-4

    420.1 General. Occupancies in Groups R-1, R-2, R-2.1, R-2.2, R-3, R-3.1 and R-4 shall comply with the provisions of Sections 420.1 through 420.11 and other applicable provisions of this code.

    420.2 Separation walls. Walls separating dwelling units in the same building, walls separating sleeping units in the same building, walls separating dwelling units from sleeping units in the same building and walls separating dwelling or sleeping units from other occupancies contiguous to them in the same building shall be constructed as fire partitions in accordance with Section 708.

    420.3 Horizontal separation. Floor assemblies separating dwelling units in the same buildings, floor assemblies separating sleeping units in the same building, floor assemblies separating dwelling units from sleeping units in the same building and floor assemblies separating dwelling or sleeping units from other occupancies contiguous to them in the same building shall be constructed as horizontal assemblies in accordance with Section 711.

    [F] 420.4 Automatic sprinkler system. Group R occupancies shall be equipped throughout with an automatic sprinkler system in accordance with Section 903.2.8. Group R-2.2 shall be equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1. Group R-2.1 occupancies shall be equipped throughout with an automatic sprinkler system in accordance with Section 903.2.6. Quick-response or residential automatic sprinklers shall be installed in accordance with Section 903.3.2.

    [F] 420.5 Fire alarm systems and smoke alarms. Fire alarm systems and smoke alarms shall be provided in Group R-1, R-2 and R-2.1 occupancies in accordance with Sections 907.2.6, 907.2.8 and 907.2.9 and 907.2.10, respectively. Single- or multiple-station smoke alarms shall be provided in Groups R-2, R-2.1, R-3 and R-4 in accordance with Section 907.2.11. Group R-2.2 shall be equipped through- out with an automatic fire alarm systems per 907.2.9.2 and shall have a manual fire alarm pull station at the 24-hour staff watch office.

    420.6 Smoke barriers in Group R-2.1 . Smoke barriers shall be provided in Group R-2.1 to subdivide every story used by persons receiving care, treatment or sleeping and to provide other stories with an occupant load of 50 or more persons, into not fewer than two smoke compartments. Such stories shall be divided into smoke compartments with an area of not more than 22,500 square feet (2092 m [2] ) and the distance of travel from any point in a smoke compartment to a smoke barrier door shall not exceed 200 feet (60 960 mm). The smoke barrier shall be in accordance with Section 709.

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    SPECIAL DETAILED REQUIREMENTS BASED ON OCCUPANCY AND USE

  • CBC § 2103.4 High relevance — show source text

    Reinforcement

    Masonry 2103.4 Shotcrete 1908 Religious Worship, Places of Accessibility Chapter 11B Alarms and detection 907.2.1 Balcony 1030.5 Classification 303.1.4, 303.4, 305.1.1, 305.2.1, 308.5.2 Door operations 1010.2.9 Egress 1030 Interior finishes Table 803.13, 804 Unlimited area 507.6, 507.7 Relocating, Building 101.4.7, 107.2.8, 3113 Compliance 3113.1.1 Inspection agencies 3113.4 Manufacturer’s data plate 3113.3 Supplemental information 3113.2 Repairs, Building 101.4.7, 202 Flood 1612.1

    Minor 105.2.2

    Permit required 105.1 Roof, Reroofing 1509, 1512 Residential Hotels (mail receptacles) 420.13.1 Residential Occupancy (Group R) 310 Accessibility Chapter 11A, 11B Alarm and detection 907.2.8, 907.2.9, 907.2.11, 907.2.12, 907.5.2.3.2,

    907.5.2.3.3

    Area 503, 505, 506, 508, 510 Carbon monoxide alarms 915 Cooking 420.10, 420.11 Draftstopping 708.4.3, 718.4 Group provisions Group R-1 (transient) 310.2 Group R-2 (apartment) 310.3 Group R-3 (two dwellings per building) 310.4 Group R-4 (group homes) 310.5 Electric vehicle charging 420.14 Height 503, 504, 505, 508, 510 Incidental uses 509

    Interior finishes Table 803.13, 804 Live load Table 1607.1

    Live/work units 508.5 Means of egress Aisles 1018.5

    Corridors 1020.2, 1020.3

    Doors 1010.1.1 Emergency escape and rescue 1031.2

    Exit signs 1013.1, 1013.2 Single exits 1006.3 Stairway, exit access 1019 Travel distance 1006.3.3, 1017.2,

    1006.2.1

    Mixed occupancies 508.3, 508.4 Accessory 508.2, G112.1 Live/work units 508.5 Parking, private 406.2.8, 406.3 Parking below/above 510.4, 510.7, 510.9

    Special mixed 510.2

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    INDEX

    Means of egress 3310 Protection of pedestrians 3306 Sanitary facilities 3305 Site work 3304

  • CBC § 308.5.1.1 High relevance — show source text

    308.5.1.1 Special provisions. See Section 452.1.4 of the California Building Code for child care locations above or below the first story.

    308.5.2 Within a place of religious worship. Rooms and spaces within places of religious worship providing such care during religious functions shall be licensed by the California State Department Health Services as required by Health and Safety Code Divi- sion 2 Chapter 3.5.

    308.5.3 Five or fewer persons receiving care. A facility having five or fewer persons receiving custodial care shall be licensed pursuant to Health and Safety Code Division 2 Chapter 3.5 or 3.6.

    308.5.4 Six or fewer persons receiving care in a dwelling unit. A facility such as the above within a dwelling unit and having six or fewer persons receiving custodial care shall be classified as a Group R-3 occupancy , where occupants are not capable of responding to an emergency situation without physical assistance from the staff shall be classified as a Group I-4.

    SECTION 309—MERCANTILE GROUP M

    309.1 Mercantile Group M. Mercantile Group M occupancy includes, among others, the use of a building or structure or a portion thereof for the display and sale of merchandise, and involves stocks of goods, wares or merchandise incidental to such purposes and where the public has access. Mercantile occupancies shall include, but not be limited to, the following:

    Department stores

    Drug stores

    Greenhouses for display and sale of plants that provide public access

    Markets

    Motor fuel-dispensing facilities

    Retail or wholesale stores

    Sales rooms

    309.2 Quantity of hazardous materials. The aggregate quantity of nonflammable solid and nonflammable or noncombustible liquid hazardous materials stored or displayed in a single control area of a Group M occupancy shall not exceed the quantities in Table 414.2.5.1.

    309.3 Motor fuel-dispensing facilities. Motor fuel-dispensing facilities shall comply with Section 406.7.

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    OCCUPANCY CLASSIFICATION AND USE

    SECTION 310—RESIDENTIAL GROUP R

    310.1 Residential Group R. Residential Group R includes, among others, the use of a building or structure, or a portion thereof, for sleeping purposes when not classified as an Institutional Group I or when not regulated by the California Residential Code . Group R occupancies not constructed in accordance with the California Residential Code as permitted by Sections 310.4.1 and 310.4.2 shall comply with Section 420.

    310.2 Residential Group R-1. Residential Group R-1 occupancies containing sleeping units or more than two dwelling units where the occupants are primarily transient in nature, including:

    Boarding houses (transient) with more than 10 occupants

    Congregate residences (transient) with more than 10 occupants

    Hotels (transient)

    Motels (transient)

    [HCD 1] Efficiency dwelling units (transient)

    310.3 Residential Group R-2. Residential Group R-2 occupancies containing sleeping units or more than two dwelling units where the occupants are primarily permanent in nature, including:

    Apartment houses

    Large family child care

    Small family child care

  • CBC § 1609.1.1.1 Medium relevance — show source text

    Exceptions:

    1. Subject to the limitations of Section 1609.1.1.1, the provisions of ICC 600 shall be permitted for applicable Group R-2 and R-3 buildings.

    2. Subject to the limitations of Section 1609.1.1.1, residential structures using the provisions of AWC WFCM.

    3. Subject to the limitations of Section 1609.1.1.1, residential structures using the provisions of AISI S230.

    4. Designs using NAAMM FP 1001.

    5. Designs using TIA-222 for antenna-supporting structures and antennas, provided that the horizontal extent of Topographic Category 2 escarpments in Section 2.6.6.2 of TIA-222 shall be 16 times the height of the escarpment.

    6. Wind tunnel tests in accordance with ASCE 49 and Sections 31.4 and 31.7 of ASCE 7.

    7. Temporary structures complying with Section 3103.6.1.2.

    The wind speeds in Figures 1609.3(1) through 1609.3(4) are basic wind speeds, V, and shall be converted in accordance with Section 1609.3.1 to allowable stress design wind speeds, V asd, when the provisions of the standards referenced in Exceptions 4 and 5 are used.

    1609.1.1.1 Applicability. The provisions of ICC 600 are applicable only to buildings located within Exposure B or C as defined in Section 1609.4. The provisions of ICC 600, AWC WFCM and AISI S230 shall not apply to buildings sited on the upper half of an isolated hill, ridge or escarpment meeting all of the following conditions:

    1. The hill, ridge or escarpment is 60 feet (18 288 mm) or higher if located in Exposure B or 30 feet (9144 mm) or higher if located in Exposure C.
    2. The maximum average slope of the hill exceeds 10 percent.
    3. The hill, ridge or escarpment is unobstructed upwind by other such topographic features for a distance from the high point of 50 times the height of the hill or 2 miles (3.22 km), whichever is greater.

    1609.2 Protection of openings. In windborne debris regions, glazing in buildings shall be impact resistant or protected with an impact-resistant covering meeting the requirements of an approved impact-resistant standard or ASTM E1996 referenced herein as follows:

    1. Glazed openings located within 30 feet (9144 mm) of grade shall meet the requirements of the large missile test of ASTM E1996.

    2. Glazed openings located more than 30 feet (9144 mm) above grade shall meet the provisions of the small missile test of ASTM E1996.

    Exceptions:

    1. Wood structural panels with a minimum thickness of [7] / 16 inch (11.1 mm) and maximum panel span of 8 feet (2438 mm) shall be permitted for opening protection in buildings with a mean roof height of 33 feet (10 058 mm) or less that are classified as a Group R-3 or R-4 occupancy. Panels shall be precut so that they shall be attached to the framing surrounding the opening containing the product with the glazed opening. Panels shall be predrilled as required for the anchorage method and shall be secured with the attachment hardware provided.
  • CBC § 11.1 Medium relevance — show source text

    1. Glazed openings located within 30 feet (9144 mm) of grade shall meet the requirements of the large missile test of ASTM E1996.

    2. Glazed openings located more than 30 feet (9144 mm) above grade shall meet the provisions of the small missile test of ASTM E1996.

    Exceptions:

    1. Wood structural panels with a minimum thickness of [7] / 16 inch (11.1 mm) and maximum panel span of 8 feet (2438 mm) shall be permitted for opening protection in buildings with a mean roof height of 33 feet (10 058 mm) or less that are classified as a Group R-3 or R-4 occupancy. Panels shall be precut so that they shall be attached to the framing surrounding the opening containing the product with the glazed opening. Panels shall be predrilled as required for the anchorage

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    STRUCTURAL DESIGN

    method and shall be secured with the attachment hardware provided. Attachments shall be designed to resist the components and cladding loads determined in accordance with the provisions of ASCE 7, with corrosion-resistant attachment hardware provided and anchors permanently installed on the building. Attachment in accordance with Table 1609 A .2 with corrosion-resistant attachment hardware provided and anchors permanently installed on the building is permitted for buildings with a mean roof height of 45 feet (13 716 mm) or less where V asd determined in accordance with Section 1609 A .3.1 does not exceed 140 mph (63 m/s). 2. Glazing in Risk Category I buildings, including greenhouses that are occupied for growing plants on a production or research basis, without public access shall be permitted to be unprotected. 3. Glazing in Risk Category II, III or IV buildings located over 60 feet (18 288 mm) above the ground and over 30 feet (9144 mm) above aggregate surface roofs located within 1,500 feet (457 m) of the building shall be permitted to be unprotected.

    TABLE 1609A.2—WINDBORNE DEBRIS PROTECTION FASTENING SCHEDULE FOR WOOD STRUCTURAL PANELSa, b, c, d Col2 Col3 Col4
    FASTENER TYPE FASTENER SPACING (inches) FASTENER SPACING (inches) FASTENER SPACING (inches)
    FASTENER TYPE Panel Span ≤ 4 feet 4 feet < Panel Span ≤ 6 feet 6 feet < Panel Span ≤ 8 feet
    No. 8 wood-screw-based anchor with 2-inch
    embedment length    		 16 10 8
    No. 10 wood-screw-based anchor with 2-inch
    embedment length    		 16 12 9
    1/4-inch diameter lag-screw-based anchor with
    2-inch embedment length    		 16 16 16
    For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound = 4.448 N, 1 mile per hour = 0.447 m/s.
    a. This table is based a on 140 mph basic wind speed,V, and a 45-foot mean roof height.
    b. Fasteners shall be installed at opposing ends of the wood structural panel.
  • CBC § 510.4 Medium relevance — show source text

    Openings between the Group S-2 enclosed parking garage and Group S-2 open parking garage, except exit openings, shall not be required to be protected. 5. The Group S-2 enclosed parking garage is used exclusively for the parking or storage of private motor vehicles, but shall be permitted to contain an office, waiting room and toilet room having a total area of not more than 1,000 square feet (93 m [2] ) and mechanical equipment rooms associated with the operation of the building.

    510.4 Parking beneath Group R. Where a maximum one story above grade plane Group S-2 parking garage, enclosed or open, or combination thereof, of Type I construction or open of Type IV construction, with grade entrance, is provided under a building of Group R, the number of stories to be used in determining the minimum type of construction shall be measured from the floor above such a parking area. The floor assembly between the parking garage and the Group R above shall comply with the type of construction required for the parking garage and shall also provide a fire-resistance rating not less than the mixed occupancy separation required in Section 508.4.

    510.5 Group R-1 and R-2 buildings of Type IIIA construction. For buildings of Type IIIA construction in Groups R-1 and R-2, the maximum allowable height in Table 504.3 shall be increased by 10 feet (3048 mm) and the maximum allowable number of stories in Table 504.4 shall be increased by one where the first-floor assembly above the basement has a fire-resistance rating of not less than 3 hours and the floor area is subdivided by 2-hour fire-resistance-rated fire walls into areas of not more than 3,000 square feet (279 m [2] ).

    510.6 Group R-1 and R-2 buildings of Type IIA construction. The height limitation for buildings of Type IIA construction in Groups R-1 and R-2 shall be increased to nine stories and 100 feet (30 480 mm) where the building is separated by not less than 50 feet (15 240 mm) from any other building on the lot and from lot lines, the exits are segregated in an area enclosed by a 2-hour fire-resistancerated fire wall and the first floor assembly has a fire-resistance rating of not less than 1 [1] / 2 hours.

    510.7 Open parking garage beneath Groups A, I, B, M and R. Open parking garages constructed under Groups A, I, B, M and R shall not exceed the height and area limitations permitted under Section 406.5. The height and area of the portion of the building above the open parking garage shall not exceed the limitations in Section 503 for the upper occupancy. The height, in both feet and stories, of the portion of the building above the open parking garage shall be measured from grade plane and shall include both the open parking garage and the portion of the building above the parking garage.

    510.7.1 Fire separation. Fire barriers constructed in accordance with Section 707 or horizontal assemblies constructed in accordance with Section 711 between the parking occupancy and the upper occupancy shall correspond to the required fire-resistance rating prescribed in Table 508.4 for the uses involved. The type of construction shall apply to each occupancy individually, except that structural members, including main bracing within the open parking structure, which is necessary to support the upper occupancy, shall be protected with the more restrictive fire-resistance-rated assemblies of the groups involved as shown in Table 601.

  • CBC § 2.1 Medium relevance — show source text

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    Chapter 3 Occupancy Classification and Use.

    Chapter 3 provides for the classification of buildings, structures and parts thereof based on the purpose for which they are used. Section 302 identifies the groups into which all buildings, structures and parts thereof must be classified. Sections 303 through 312 identify the occupancy characteristics of each group classification. In some sections, specific group classifications having requirements in common are collectively organized such that one term applies to all. For example, Groups A-1, A-2, A-3, A-4 and A-5 are individual groups for assembly-type buildings. The general term “Group A,” however, includes each of these individual groups. Other groups include Business (B), Organized Camps (C), Educational (E), Factory (F-1, F-2), High Hazard (H-1, H-2, H-3, H-4, H-5), Institutional (I-2, I-3, I-4), Laboratories (L), Mercantile (M), Residential (R-1, R-2, R-2.1, R-2.2, R-3, R-3.1, R-4), Storage (S-1, S-2) and Utility (U). In some occupancies, the smaller number means a higher hazard, but that is not always the case.

    Defining the use of the buildings is very important as it sets the tone for the remaining chapters of the code. Occupancy works with the height, area and construction type requirements in Chapters 5 and 6, to determine "equivalent risk." The determination of equivalent risk involves three interdependent considerations: (1) the level of fire hazard associated with the specific occupancy of the facility; (2) the reduction of fire hazard based on the fuel load by limiting the floor area and the height of the building; and (3) the level of overall fire resistance provided by the type of construction. The greater the potential fire hazards indicated as a function of the group, the lesser the height and area allowances for a particular construction type.

    Occupancy classification also plays a key part in the appropriate protection measures. As such, threshold requirements for fire protection and means of egress systems are based on occupancy classification (see Chapters 9 and 10). Other sections of the code also contain requirements respective to the classification of building groups. For example, Section 706 specifies requirements for fire wall fire-resistance ratings that are tied to the occupancy classification of a building and Section 803.11 contains interior finish requirements that are dependent upon the occupancy classification. The use of the space, rather than the occupancy of the building, is utilized for determining occupant loading (Section 1004) and live loading (Section 1607).

    Chapter 4 Special Detailed Requirements Based on Occupancy and Use.

    Chapter 4 contains the requirements for protecting special uses and occupancies which are supplemental to the remainder of the code. For example, the height and area limitations established in Chapter 5 apply to all special occupancies unless Chapter 4 contains height and area limitations. In this case, the limitations in Chapter 4 supersede those in other sections. An example of this is the height and area limitations for open parking garages given in Section 406.5.4, which supersede the limitations given in Sections 504 and 506.

  • CBC § 301.1 Medium relevance — show source text

    ICC code development note: Code change proposals to sections preceded by the designation [F] will be considered by the IFC code development committee meeting during the 2024 (Group A) Code Development Cycle. All other code change proposals will be considered by a code development committee meeting during the 2025 (Group B) Code Development Cycle.

    SECTION 301—SCOPE

    301.1 General. The provisions of this chapter shall control the classification of all buildings and structures as to occupancy and use. Different classifications of occupancy and use represent varying levels of hazard and risk to building occupants and adjacent properties.

    SECTION 302—OCCUPANCY CLASSIFICATION AND USE DESIGNATION

    302.1 Occupancy classification. Occupancy classification is the formal designation of the primary purpose of the building, structure or portion thereof. Structures shall be classified into one or more of the occupancy groups specified in this section based on the nature of the hazards and risks to building occupants generally associated with the intended purpose of the building or structure. An area, room or space that is intended to be occupied at different times for different purposes shall comply with all applicable requirements associated with such potential multipurpose. Structures containing multiple occupancy groups shall comply with Section 508. Where a structure is proposed for a purpose that is not specified in this section, such structure shall be classified in the occupancy it most nearly resembles based on the fire safety and relative hazard. Occupiable roofs shall be classified in the group that the occupancy most nearly resembles, according to the fire safety and relative hazard, and shall comply with Section 503.1.4.

    1. Assembly (see Section 303): Groups A-1, A-2, A-3, A-4 and A-5.
    2. Business (see Section 304): Group B. 3. [SFM] Organized Camps (see Section 450): Group C. 4. Educational (see Section 305): Group E. 5. Factory and Industrial (see Section 306): Groups F-1 and F-2. 6. High Hazard (see Section 307): Groups H-1, H-2, H-3, H-4 and H-5. 7. Institutional (see Section 308): Groups I-2, I-3 and I-4. 8. [SFM] Laboratory (see Section 202): Group B, unless classified as Group L (see Section 453) or Group H (see Section 307). 9. [SFM] Laboratory Suites (see Section 453): Group L. 10. Mercantile (see Section 309): Group M. 11 . Residential (see Section 310): Groups R-1, R-2, R-2.1, R-3, R-3.1 and R-4. 12 . Storage (see Section 311): Groups S-1 and S-2. 13 . Utility and Miscellaneous (see Section 312): Group U. 14. [SFM] Existing buildings housing existing protective social care homes or facilities established prior to 1972 (see California Fire Code Chapter 11 and California Existing Building Code).

    302.1.1 Reserved

    302.1.2 Reserved

    302.1.3 Pharmacies; veterinary facilities; barbering, cosmetology or electrolysis establishments; and acupuncture offices. See Chapter 12.

  • CBC § 1511.9 Medium relevance — show source text

    Railing (see Guards And Handrails) Raised-deck System 1511.9 Ramps 1012 Assembly occupancy 1030.14 Construction 1012.2, 1012.5.3, 1012.7,

    1012.10

    Exit 1023

    Exit access 1019

    Exterior 1027

    Guards 1012.9, 1015, 1607.9 Handrails 1012.8, 1014, 1607.9 Interior 1012.2 Landings 1012.6 Parking garage 406.4.3 Slope 1012.2 Recreational Facilities Accessibility Chapter 11B Amusement rides Chapter 11B Play structure 402.6.3, 424 Special amusement areas (see Amusement Areas, Special) Referenced Standards Chapter 35 Applicability 102.3, 102.4 Fire resistance 703.2

    List Chapter 35 Organizations Chapter 35 Reformatories

    [see Institutional (Group I-3)] 308.4 Refrigeration (see Mechanical) 101.4.2 Machinery room 1006.2.2.2

    Refuge Areas (see Horizontal Exit, Smoke Compartments, Storm Shelters) 407.5.3, 408.6.2, 420.6.1, 422.3.2, 423, 423.3, 423.4, 1026.4 Refuse Chute 713.13

    Reinforcement

    Masonry 2103.4 Shotcrete 1908 Religious Worship, Places of Accessibility Chapter 11B Alarms and detection 907.2.1 Balcony 1030.5 Classification 303.1.4, 303.4, 305.1.1, 305.2.1, 308.5.2 Door operations 1010.2.9 Egress 1030 Interior finishes Table 803.13, 804 Unlimited area 507.6, 507.7 Relocating, Building 101.4.7, 107.2.8, 3113 Compliance 3113.1.1 Inspection agencies 3113.4 Manufacturer’s data plate 3113.3 Supplemental information 3113.2 Repairs, Building 101.4.7, 202 Flood 1612.1

    Minor 105.2.2

    Permit required 105.1 Roof, Reroofing 1509, 1512 Residential Hotels (mail receptacles) 420.13.1 Residential Occupancy (Group R) 310 Accessibility Chapter 11A, 11B Alarm and detection 907.2.8, 907.2.9, 907.2.11, 907.2.12, 907.5.2.3.2,

    907.5.2.3.3

  • CBC § 3-5 Medium relevance — show source text

    304 Business Group B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5

    305 Educational Group E . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5

    306 Factory Group F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6

    307 High-Hazard Group H . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7

    308 Institutional Group I . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-13

    309 Mercantile Group M. . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-14

    310 Residential Group R. . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-15

    311 Storage Group S. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-17

    312 Utility and Miscellaneous Group U . . . . . . . . . . . . . . 3-18

    313 Laboratories Group L [SFM]. . . . . . . . . . . . . . . . . . . . . . .3-19

    314 Organized Camps Group C [SFM]. . . . . . . . . . . . . . . . . .3-19

    CHAPTER 4 SPECIAL DETAILED REQUIREMENTS

    BASED ON OCCUPANCY AND USE . . . . . . . . . . . . . . . . . . . .4-1

    401 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5

    402 Covered Mall and Open Mall Buildings . . . . . . . . . . . . 4-5

    403 High-Rise Buildings and Group I-2 Occupancies Having Occupied Floors Located More Than 75 Feet above the Lowest Level of

    Fire Department Vehicle Access . . . . . . . . . . . . . . . 4-9

    404 Atriums. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-12

    405 Underground Buildings . . . . . . . . . . . . . . . . . . . . . . . . 4-13

    406 Motor-Vehicle-Related Occupancies. . . . . . . . . . . . . 4-15

    407 Group I-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-19

    408 Group I-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-24

  • CBC § 1.5 Medium relevance — show source text

    ; clips C, E; reinforcement: none;1/2″ plas-
    ter, 1.5:2.5 mill mix.|N/A|55 min|||3|5, 8|3/4|

    RESOURCE A-96 2025 CALIFORNIA EXISTING BUILDING CODE

    on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

    RESOURCE A—GUIDELINES ON FIRE RATINGS OF ARCHAIC MATERIALS AND ASSEMBLIES

    TABLE 3.2—continued
    FLOOR/CEILING ASSEMBLIES—STEEL STRUCTURAL ELEMENTS    		 Col2 Col3 Col4 Col5 Col6 Col7 Col8 Col9 Col10
    ITEM
    CODE    		 MEMBRANE
    THICKNESS    		 CONSTRUCTION DETAILS PERFORMANCE PERFORMANCE REFERENCE NUMBER REFERENCE NUMBER REFERENCE NUMBER NOTES REC.
    HOURS
    ITEM
    CODE    		 MEMBRANE
    THICKNESS    		 CONSTRUCTION DETAILS LOAD TIME PRE-BMS-92 BMS-92 POST-BMS-92 POST-BMS-92 POST-BMS-92
    F/C-S-8 1/2″ Spec. 9′ × 4′4″; S.J. 103 bar joists, 18″ o.c.;
    deck: 4 lbs rib lath base; 6″ × 6″ 10 × 10 gage
    reinforcement; 2″ deck 1:2:4 gravel concrete;
    membrane: furring,3/4″ C.R.S., 16″ o.c.; clips C,
    E; reinforcement: none;1/2″ plaster, 1.5:2.5
    mill mix.    		 300 psf 1 hr
    10 min    		 3 2, 3, 8 1
    F/C-S-9 5/8″ 10′ × 13′6″; S.J. 103, 24″ o.c.; deck: 2″
    concrete, 1:2:4; membrane: furring 12″ o.c.;
    clips A, B, G; Extra “A” clips reinforcement;5/8″
    plaster, 1.5:2, 1.5:3.    		 145 psf 3 hrs 3 6, 8 3
    F/C-S-10 5/8″ 18′ × 13′6″; joists, S.J. 103, 24″ o.c.; deck: 4 lbs
    rib lath; 6″ × 6″ 10 × 10 gage reinforcement; 2″
    deck, 1:2:3.5 gravel concrete; membrane:
    furring, spacing 16″ o.c.

Frequently asked questions

What is the single quickest test to distinguish R‑1 from R‑2?

Ask whether the occupants are primarily transient (short‑term/nightly) or primarily permanent (long‑term). If transient, CBC examples place the use in R‑1; if permanent, R‑2. See §§ 310.2 and 310.3.

Do the number of dwelling units matter?

Yes — the CBC uses the phrase “sleeping units or more than two dwelling units” when describing Group R applicability; multi‑unit buildings commonly fall into R groups and the number of units is one factor in classification (see § 310.1 and §§ 310.2–310.3).

Are licensed care facilities treated differently?

Yes. § 310.3 includes R‑2 subcategories (R‑2.1, R‑2.2) for supervised 24‑hour care environments; Chapter 4 and Section 420 add special sprinkler, alarm and compartmenting requirements, and Section 435 contains further provisions for licensed 24‑hour care. filefile

If a dwelling has three apartments but tenants are mostly short‑term (Airbnb), which group applies?

If occupants are primarily transient the building would be evaluated as R‑1 under § 310.2 (transient occupancies such as hotels and motels are listed there). Always confirm with the AHJ because mixed or converted uses can require more detailed review.

Where do I check for required sprinklers or fire alarms once I’ve classified the occupancy?

See Section 420 (Group R special detailed requirements) for sprinkler and alarm system requirements and cross references to § 903 (sprinklers) and § 907 (fire alarms) as applied to Group R occupancies.

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Assembly Group A — classification, small-assembly exceptions

Institutional Group I — classifications and I‑4 (day care) rules

Assembly, Residential & Institutional occupancies

California Building Code