CRC · California Residential Code
Which standard is referenced for storm shelter design and construction?
If the California code requires a storm shelter (see **§ 303.1.1** and **§ 303.2**), the shelter must be designed and constructed to the ICC/NSSA 500 standard (ICC 500); the code also cross‑references CBC §423 for where shelters are required and additional location/occupancy rules.
Last reviewed: July 6, 2026
What the code requires — plain English (controlling §)
Storm shelters required by the California Existing/Residential standards must be designed and built to the ICC/NSSA 500 standard (ICC 500). Specifically, § 303.1.1 says storm shelters must be constructed in accordance with Section 423 of the California Building Code and ICC 500 . Where an addition to a Group E occupancy meets certain wind‑speed and occupant‑load thresholds, § 303.2 requires the addition to have a storm shelter constructed in accordance with ICC 500 .
The single most important rule: If the code says “construct in accordance with ICC 500,” you must use ICC/NSSA 500 for the storm‑shelter design and construction details (materials, structural design, openings, capacity, etc.) — the California code points you to ICC 500 as the controlling shelter standard.
Requirements in detail
What standard controls?
- The controlling standard for storm‑shelter design and construction is ICC/NSSA 500 (ICC 500). This is the referenced standard called out directly by § 303.1.1 and § 303.2. The code also ties storm‑shelter provisions to Section 423 of the California Building Code (CBC §423), so implementors must follow both the CBC storm‑shelter requirements and ICC 500 where the code references them. § 303.1.1 ; CBC §423 .
When ICC 500 is required (key triggers)
- If a storm shelter is required under the code, it must be designed and constructed per ICC 500 (see § 303.1.1) .
- For additions to existing Group E occupancies: when the local shelter design wind speed for tornadoes is 250 mph (per ICC 500 Figure 304.2(1)) and the addition’s occupant load is 50 or more, the addition must provide a storm shelter constructed in accordance with ICC 500 (see § 303.2) .
Decision‑relevant values (quick reference table)
| Decision item | Threshold / value | What it triggers | Code reference |
|---|---|---|---|
| Referenced shelter standard | ICC/NSSA 500 (ICC 500) | Mandatory design & construction standard for required shelters | § 303.1.1 |
| CBC storm‑shelter cross‑reference | Section 423 (CBC) | Additional location, occupancy, travel‑distance and Risk Category rules to follow with ICC 500 | § 303.1.1 + CBC §423 |
| Tornado shelter design wind speed (trigger) | 250 mph (per ICC 500 Fig. 304.2(1)) | If area has this value and addition occupant load ≥ 50, ICC 500 shelter required for the addition | § 303.2 |
| Occupant‑load threshold for Group E additions | 50 occupants | Addition must provide storm shelter per ICC 500 (when 250 mph applies) | § 303.2 |
| Travel distance (CBC requirement) | 1,000 feet | Location/ travel‑distance limits for shelters in CBC §423 (exceptions apply) | CBC §423.4.2 / §423.5.2 |
How the California code and ICC 500 interact
- The California code directs designers to ICC 500 for detailed shelter requirements (structural resistance, openings, egress, capacity, ventilation, etc.) while retaining CBC §423 for where shelters are required and some California‑level rules (for example, travel distance, occupancy classification, and Risk Category determinations) — follow both where the code references them. § 303.1.1 and CBC §423 together point to ICC 500 as the technical standard.
Exceptions & special cases
- The Exception in § 303.1.1: Storm shelters added to critical emergency operations facilities or Group E occupancies are not required to comply with the travel distance limits in CBC § 423.4.2 or § 423.5.2 (i.e., distance requirements in the CBC may be relaxed for those shelters) — but ICC 500 still governs the shelter construction. § 303.1.1 ; CBC §423 text and distance rules .
- For an addition to a Group E site that cannot physically accommodate the required occupant capacity for the entire site, there are allowances in CBC §423 (and CEBC 303.2.1) that permit a shelter sized for just the addition or to reduce required capacity if existing shelters on site already provide capacity — see § 303.2.1 for design occupant capacity rules and exceptions. § 303.2 and § 303.2.1 .
- Specific exclusions for Group E: day care facilities and occupancies accessory to places of religious worship are listed exceptions to the Group E addition rule in § 303.2. § 303.2 .
Common mistakes
- Assuming “ICC 500 is optional.” — Wrong: when the code requires a shelter, ICC 500 is the mandatory design standard per § 303.1.1 and § 303.2 .
- Ignoring the CBC §423 requirements. The state code requires compliance with both CBC §423 and ICC 500 where referenced; designers often forget the CBC’s location/occupancy provisions that work in tandem with ICC 500 .
- Misreading the 250 mph statement: the 250 mph figure is a shelter design wind‑speed trigger referenced to ICC 500 Figure 304.2(1) — you must confirm the local wind‑speed classification per ICC 500 before applying the Group E addition rule in § 303.2 .
- Treating the 50‑occupant threshold as “design occupant capacity” for the whole site (instead of the addition). For additions, § 303.2 applies when the addition’s occupant load is 50 or more; design occupant capacity rules (including when capacity must include all buildings on site) are addressed in § 303.2.1 .
Worked example — concrete scenario
Scenario: You are adding two classrooms to an existing K–12 school (Group E). The addition will hold 60 students (occupant load = 60) and is located in a jurisdiction where the ICC 500 shelter‑design wind speed map indicates 250 mph for tornadoes.
Step 1 — Check the trigger: ICC 500 wind speed = 250 mph and addition occupant load = 60 (≥ 50) → § 303.2 applies, so the addition must have a storm shelter constructed in accordance with ICC 500 .
Step 2 — Determine required shelter capacity: Per § 303.2.1, the required design occupant capacity of the shelter generally “shall include all buildings on the site” and be the total occupant load of classrooms, vocational rooms and offices — but Exception 1 to § 303.2.1 allows, when the addition cannot accommodate the whole‑site requirement, that the shelter at minimum accommodate the required capacity for the addition. If no existing shelter capacity is available and the site is required to provide whole‑site capacity, you would size the shelter to the total site occupant load; if the addition is small and code official approves, you may size just for the addition. See § 303.2.1 for the exceptions and reduction options .
Step 3 — Design & construct per ICC 500: Implement ICC/NSSA 500 (selecting the appropriate occupancy type — tornado, hurricane, or combined) for structural design, openings protection, egress, ventilation, and other shelter details. The California code requires use of ICC 500 as the construction/design standard (CBC §423 + CEBC §303.1.1 / §303.2) .
Related provisions (quick list)
- § 303.1.1 — Construction requirement: use CBC §423 and ICC 500.
- § 303.2 — Additions to Group E occupancies — 250 mph + 50 occupant trigger for ICC 500 requirement.
- § 303.2.1 — Design occupant capacity rules and exceptions for shelters serving additions.
- CBC § 423 — Where shelters are required, occupancy classification, travel distance (1,000 ft), Risk Category guidance and additional shelter requirements; used together with ICC 500.
Code references
Grounded in the retrieved California Residential Code — click a citation to read the verbatim passage:
CRC § 101.2 High relevance — show source text
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
REFERENCED STANDARDS
CRC—25: California Residential Code
101.2, 101.4.1, 104.3.1, 109.3.3, 109.3.10, 302.2, 307.1, 308.1, 401.3, 402.1, 405.2.6, 502.2, 502.3, 502.4, 503.2, 503.3, 503.11, 505.2, 505.3, 507.3, 701.3, 702.4, 702.5, 706.2, 708.1, 805.2, 806.4, 809.1, 906.2, 907.1, 1011.2.1, 1103.1, 1103.2, 1103.3, 1104.1, 1201.4, 1302.1.2, 1302.1.3, 1302.1.3, 1303.1.3, 1401.2, 1402.1, 1402.2, 1402.2.1, 1402.3, 1402.4, 1402.5, 1402.6
ICC 300—2023: ICC Standard on Bleachers, Folding and Telescopic Seating and Grandstands
301.1.1, 401.1.1, 1401.1.1
ICC A117.1—2017: Accessible and Usable Buildings and Facilities
502.6, 503.18, 1011.4, 1101.6
ICC/NSSA 500—2020: ICC/NSSA Standard for the Design and Construction of Storm Shelters
303.1.1, 303.2
ICCPC—24: ICC Performance Code®
104.2.3
IFGC—24: International Fuel Gas Code®
IPMC—24: International Property Maintenance Code®
101.4.2, 302.2, 1303.1.2, 1401.2
NFPA National Fire Protection Association, 1 Batterymarch Park, Quincy, MA 02169-7471
NFPA 72— 25 : National Fire Alarm and Signaling Code
Revise Section 10.3.1 as follows:
10.3.1 Equipment constructed and installed in conformity with this Code shall be listed for the purpose for which it is used. Fire alarm systems and components shall be California State Fire Marshal approved and listed in accordance with California Code of Regulations, Title 19, Division 1.
Revise Section 10.3.3 as follows:
10.3.3 All devices and appliances that receive their power from the initiating device circuit or signaling line circuit of a control unit shall be California State Fire Marshal listed for use with the control unit.
Revise Section 12.3.8.1 as follows:
12.3.8.1 The outgoing and return (redundant) circuit conductors shall be permitted in the same cable assembly (i.e., multiconductor cable), enclosure or raceway only under the following conditions:
CRC § 1.1 High relevance — show source text
CBC—25: California Building Code R101.2, R202, R301.1.1, R301.1.3, R301.2.1.1, R301.2.2.1.1, R301.2.2.1.2, R301.3, Table R302.1(1), Table R302.1(2), R302.2.1, R302.2.2, R302.3, R302.15.4, R322.1, R322.3, R324.5, R403.1.8, Table R602.10.3(3), Table R606.12.2.1, R609.2, R905.10.3
CEBC—25: California Existing Building Code [®]
R110.2, N1109.2
CFC—25: California Fire Code [®]
R102.6, R329.2, N1109.2, M2201.7, G2402.3, G2412.2
CWUIC—25: California Wildland-Urban Interface Code
R102.8, R337, R806.1.1, R907.1.1
ICC 400—2022: Standard on the Design and Construction of Log Structures
R301.1.1, R502.1.4, R602.1.4, R703.1, R802.1.3
ICC 500—2020: ICC/NSSA Standard for the Design and Construction of Storm Shelters
R307.1
ICC 600—2020: 2020 Standard for Residential Construction in High-Wind Regions
R301.2.1.1
ICC 1100—2019: Standard for Spray-applied Polyurethane Foam Plastic Insulation
R303.1.1
IPMC—24: International Property Maintenance Code [®]
R102.6
ISO International Organization for Standardization Chemin de Blandonnet 8 Geneva, Switzerland CP 401 - 1214
8336—2009: Fibre-cement Flat Sheets—Product Specification and Test Methods Table R503.2.1.1(1), Table R503.2.1.1(2), Table R602.3(2), Table R702.4.2, R703.10.1, R703.10.2
44-16 2025 CALIFORNIA RESIDENTIAL CODE
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REFERENCED STANDARDS
NFPA National Fire Protection Association 1 Batterymarch Park Quincy, MA 02169-7471
13D— 25 : Standard for the Installation of Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes as amended*
R309.1.1, R309.2.1, R309.3.1, R309.3.1.1, R309.3.2.3, R309.3.6.1, R329.6.2.1
*See California Fire Code for amendments
*NFPA 13D, Amended Sections as follows:
CRC § 302.3 High relevance — show source text
302.3 Existing materials. Materials already in use in a building in compliance with requirements or approvals in effect at the time of their erection or installation shall be permitted to remain in use unless determined by the code official to be unsafe.
302.4 New and replacement materials. Except as otherwise required or permitted by this code, materials permitted by the applicable code for new construction shall be used. Like materials shall be permitted for repairs and alterations, provided that unsafe conditions are not created. Hazardous materials shall not be used where the code for new construction would not permit their use in buildings of similar occupancy, purpose and location. [HCD 1] Local ordinances or regulations shall permit the replacement, retention and extension of original materials, and the use of original methods of construction, for any building or accessory structure, provided such building or structure complied with the building code provisions in effect at the time of original construction and the building or accessory structure does not become or continue to be a substandard building. For additional information, see Health and Safety Code Sections 17912, 17920.3, 17922(d), 17922.3, 17958.8 and 17958.9.
Exception: No replacement residential garage door shall be installed to connect the replacement door to an existing residential automatic garage door opener that does not have a battery backup function designed to keep the garage door operational without interruption during an electrical outage. See Health and Safety Code Section 19892.
[BS] 302.4.1 New structural members and connections. New structural members and connections shall comply with the detailing provisions of the California Building Code for new buildings of similar structure, purpose and location.
Exception: Where alternative design criteria are specifically permitted.
302.5 Occupancy and use. Where determining the appropriate application of the referenced sections of this code, the occupancy and use of a building shall be determined in accordance with Chapter 3 of the California Building Code .
SECTION 303—STORM SHELTERS
303.1 General. This section applies to the design and construction of storm shelters for the purpose of providing protection during tornadoes, hurricanes and other severe windstorms.
3-4 2025 CALIFORNIA EXISTING BUILDING CODE
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PROVISIONS FOR ALL COMPLIANCE METHODS
303.1.1 Construction. Storm shelters shall be constructed in accordance with Section 423 of the California Building Code and ICC 500 and shall be designated as hurricane shelters, tornado shelters or combined hurricane and tornado shelters.
Exception: Storm shelters added to critical emergency operations facilities or Group E occupancies are not required to comply with the travel distance in Section 423.4.2 or 423.5.2 of the California Building Code .
303.2 Addition to a Group E occupancy. Where an addition is added to an existing Group E occupancy located in an area where the shelter design wind speed for tornadoes is 250 mph (402.3 km/h) in accordance with Figure 304.2(1) of ICC 500 and the occupant load in the addition is 50 or more, the addition shall have a storm shelter constructed in accordance with ICC 500.
Exceptions:
- Group E day care facilities.
- Group E occupancies accessory to places of religious worship.
- Additions meeting the requirements for shelter design in ICC 500.
CRC § 302.5 High relevance — show source text
302.5 Occupancy and use. Where determining the appropriate application of the referenced sections of this code, the occupancy and use of a building shall be determined in accordance with Chapter 3 of the California Building Code .
SECTION 303—STORM SHELTERS
303.1 General. This section applies to the design and construction of storm shelters for the purpose of providing protection during tornadoes, hurricanes and other severe windstorms.
3-4 2025 CALIFORNIA EXISTING BUILDING CODE
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PROVISIONS FOR ALL COMPLIANCE METHODS
303.1.1 Construction. Storm shelters shall be constructed in accordance with Section 423 of the California Building Code and ICC 500 and shall be designated as hurricane shelters, tornado shelters or combined hurricane and tornado shelters.
Exception: Storm shelters added to critical emergency operations facilities or Group E occupancies are not required to comply with the travel distance in Section 423.4.2 or 423.5.2 of the California Building Code .
303.2 Addition to a Group E occupancy. Where an addition is added to an existing Group E occupancy located in an area where the shelter design wind speed for tornadoes is 250 mph (402.3 km/h) in accordance with Figure 304.2(1) of ICC 500 and the occupant load in the addition is 50 or more, the addition shall have a storm shelter constructed in accordance with ICC 500.
Exceptions:
- Group E day care facilities.
- Group E occupancies accessory to places of religious worship.
- Additions meeting the requirements for shelter design in ICC 500.
303.2.1 Design occupant capacity. The required design occupant capacity of the storm shelter shall include all buildings on the site, and shall be the total occupant load of the classrooms, vocational rooms and offices in the Group E occupancy.
Exceptions:
- Where an addition is being added on an existing Group E site, and where the addition is not of sufficient size to accommodate the required occupant capacity of the storm shelter for all of the buildings on-site, the storm shelter shall at a minimum accommodate the required capacity for the addition.
- Where approved by the code official, the required design occupant capacity of the shelter shall be permitted to be reduced by the design occupant capacity of any existing storm shelters on the site.
303.3 Occupancy classification. The occupancy classification for storm shelters shall be determined in accordance with Section 423.3 of the California Building Code .
SECTION 304—STRUCTURAL DESIGN LOADS AND EVALUATION AND DESIGN PROCEDURES
[BS] 304.1 Live loads. Where an addition or alteration does not result in increased design live load, existing gravity load-carrying structural elements shall be permitted to be evaluated and designed for live loads approved prior to the addition or alteration. If the approved live load is less than that required by Section 1607 of the California Building Code, the area designated for the nonconforming live load shall be posted with placards of approved design indicating the approved live load. Where the addition or alteration results in increased design live load, the live load required by Section 1607 of the California Building Code shall be used.
[BS] 304.2 Snow loads on adjacent buildings. Where an alteration or addition changes the potential snow drift effects on an adjacent building, the code official is authorized to enforce Section 7.12 of ASCE 7.
CRC § 5704.2.8.9 High relevance — show source text
1, 5704.2.8.9, 5705.3.7.5.1, 5706.2, 5706.4.4, 6003.1.3, 6003.2.3.2, 6004.2.2.7, 6005.3.1, 6005.3.2, 6103.2.1.7
CPC—25: California Plumbing Code
201.3, 903.3.5, 904.11.1.3, 912.6, 2311.2.3, 5004.2.2.6
CRC—25: California Residential Code
102.5, 202, 913.1, 1001.1, 1205.1, 1205.2.1
ICC 300—2017: Standard on Bleachers, Folding and Telescopic Seating and Grandstands
1030.1.1, 1030.17
ICC ES AC 331: Acceptance Criteria for Smoke and Heat Vents
910.3.1
ICC 500—2020: ICC/NSSA Standard on the Design and Construction of Storm Shelters
1031.2
ICC A117.1—2017: Accessible and Usable Buildings and Facilities
907.5.2.3.3, 1009.2.2, 1009.8.2, 1009.9, 1009.11, 1010.2.12.1, 1012.1, 1012.6.5, 1012.10, 1013.4, 1023.11
IFGC—24: International Fuel Gas Code®
201.3, 605.1, 605.2.1.3, 605.3, 605.5.2, 605.7, 610.1.1, 1206.9, 2301.1, 2301.6, 2308.1, 2309.3.1.2, 2309.3.1.5, 2504.5, 3001.1, 3003.1, 3004.1, 3004.2, 3108.12.1, 3108.12.2, 3305.1.2, 3309.2.2, 4101.6.1, Table 5003.1.1(1), 5301.1, 5801.1, 5803.1.4, 6103.1, 6103.2.1.7,
6103.3
IIAR International Institute of Ammonia Refrigeration, 1001 N. Fairfax Street, Suite 503, Alexandria, VA 22314
ANSI/IIAR 2—2021: Safe Design of Closed-Circuit Ammonia Refrigeration Systems
608.1.2, 608.9
ANSI/IIAR 6—2019: Standard for Inspection, Testing, and Maintenance of Closed-Circuit Ammonia Refrigeration Systems
608.1.2
ANSI/IIAR 7—2019: Developing Operating Procedures for Closed-Circuit Ammonia Refrigeration Systems
608.1.2
ANSI/IIAR 8—2020: Decommissioning of Closed-Circuit Ammonia Refrigeration Systems
608.1.2
CRC § 1506.1 High relevance — show source text
1506.1 Standpipe Systems 105.2.2, 1305.2.18, 1305.2.18.1, Table 1305.2.18, Table 1306.1, 1503.2, 1506 Storm Shelter 303
Structural 304.1, 405, 502.3, 502.4, 503.3, 503.4, 503.5, 503.6, 503.7, 503.8, 503.9, 503.10, 503.11, 503.12, 503.13, 506.5, 507.4, 706, 805, 906, 1006, 1103, 1304.1.1, 1402 Structural Loads/Forces Gravity loads A403.10.1, A403.10.2, A403.5, 202, 304.1, 405.2.4, 405.2.4.1, 502.3, 503.3, 706.2, 805.2, 1007.1,
1103.1 International Building Code -level 506.5.3, 506.5.4, 1006.3, 1103.2,
1402.4
Live loads 804.4.1.2.2, A106.2.3.6, A403.7, A104.1, A108.3, A108.6, 202, 304.1, 405.2.4, 502.3, 503.3, 504.3, 506.5.1, 507.4, 706.2, 805.2, 1006.1, 1103.1, 1504.1.1, 1504.1.5 Reduced 304.3.2, Table 304.3.2, 405.2.3.1, 405.2.3.3, 503.10, 503.11, 503.4, 503.5, 503.6, 503.7, 503.8, 503.9, 506.5.3, 706.3.1, 805.3, 906.2, 906.3, 906.4, 906.5, 906.6, 906.7,
1006.3
Repairs 405 Seismic loads Appendix a, 202, 304.3, 405.2.3, 405.2.4.1, 502.2, 502.4, 503.10, 503.11, 503.13, 503.4, 503.5, 503.6, 503.7, 503.8, 503.9, 506.5.3, 506.5.4, 706.3.1, 805.3, 906.2, 906.3, 906.4, 906.5, 906.6, 906.7, 1006.3, 1006.4, 1103.2, 1402.4
INDEX-2 2025 CALIFORNIA EXISTING BUILDING CODE
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INDEX
CRC § 2311.3.1 High relevance — show source text
2, 2311.3.1, 2311.4.3, 2311.8.2, 2311.8.8, 2311.8.10, 2404.9, 2404.9.2, 2504.5, 2703.2.2, 2703.10.4, 2703.14, 2803.2, 2803.3, 3001.1, 3003.1, 3004.2, 3108.12.1, 3108.12.2, 3703.5, 3804.1.1.7, 3904.1, 3905.3, Table 5003.1.1(1), 5003.8.4.2, 5003.8.5.2, 5003.8.6.2, 5004.3.1, 5303.7.6, 5303.16.9, 5305.5, 5306.2.2, 5306.2.3, 5307.4.4, 5504.2.1.3, 5504.2.2.3, 5505.4.1.1, 5701.3, 5703.6.1, 5704.2.8.9, 5705.3.7.5.1, 5706.2, 5706.4.4, 6003.1.3, 6003.2.3.2, 6004.2.2.7, 6005.3.1, 6005.3.2, 6103.2.1.7
CPC—25: California Plumbing Code
201.3, 903.3.5, 904.11.1.3, 912.6, 2311.2.3, 5004.2.2.6
CRC—25: California Residential Code
102.5, 202, 913.1, 1001.1, 1205.1, 1205.2.1
ICC 300—2017: Standard on Bleachers, Folding and Telescopic Seating and Grandstands
1030.1.1, 1030.17
ICC ES AC 331: Acceptance Criteria for Smoke and Heat Vents
910.3.1
ICC 500—2020: ICC/NSSA Standard on the Design and Construction of Storm Shelters
1031.2
ICC A117.1—2017: Accessible and Usable Buildings and Facilities
907.5.2.3.3, 1009.2.2, 1009.8.2, 1009.9, 1009.11, 1010.2.12.1, 1012.1, 1012.6.5, 1012.10, 1013.4, 1023.11
IFGC—24: International Fuel Gas Code®
CRC § 423.3.2 High relevance — show source text
- The occupancy category for a dedicated residential storm shelter shall be the Group R occupancy served.
423.3.2 Storm shelters within host buildings. Where designated storm shelters are constructed as a room or space within a host building that will normally be occupied for other purposes, the requirements of this code for the occupancy of the building, or the individual rooms or spaces thereof, shall apply unless otherwise required by ICC 500.
423.4 Critical emergency operations. In areas where the shelter design wind speed for tornados in accordance with Figure 304.2(1) of ICC 500 is 250 mph, 911 call stations, emergency operation centers and fire, rescue, ambulance and police stations shall comply with Table 1604.5 as a Risk Category IV structure and shall be provided with a storm shelter constructed in accordance with ICC 500.
423.4.1 Design occupant capacity. The required design occupant capacity of the storm shelter shall include the critical emergency operations on the site and shall be the total occupant load of offices and the number of beds.
Exceptions:
- Where approved by the building official, the actual number of occupants for whom each occupied space, floor or building is designed, although less than that determined by occupant load calculation, shall be permitted to be used in the determination of the required design occupant capacity for the storm shelter.
- Where a new building is being added on an existing site, and where the new building is not of sufficient size to accommodate the required design occupant capacity of the storm shelter for all of the buildings on the site, the storm shelter shall accommodate not less than the required occupant capacity of the new building.
- Where approved by the building official, the required design occupant capacity of the shelter shall be permitted to be reduced by the design occupant capacity of any existing storm shelters on the site.
423.4.2 Location. Storm shelters shall be located within the building they serve or shall be located where the distance of travel from not fewer than one exterior door of each building to a door of the shelter serving that building does not exceed 1,000 feet (305 m), unless otherwise approved.
423.5 Group E occupancies. In areas where the shelter design wind speed for tornados is 250 mph in accordance with Figure 304.2(1) of ICC 500, all Group E occupancies with an occupant load of 50 or more shall have a storm shelter constructed in accordance with ICC 500.
Exceptions:
- Group E day care facilities.
- Group E occupancies accessory to places of religious worship.
- Buildings meeting the requirements for shelter design in ICC 500.
2025 CALIFORNIA BUILDING CODE 4-55
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SPECIAL DETAILED REQUIREMENTS BASED ON OCCUPANCY AND USE
423.5.1 Design occupant capacity. The required design occupant capacity of the storm shelter shall include all of the buildings on the site and shall be the total occupant load of the classrooms, vocational rooms and offices in the Group E occupancy.
Exceptions:
- Where approved by the building official, the actual number of occupants for whom each occupied space, floor or building is designed, although less than that determined by occupant load calculation, shall be permitted to be used in the determination of the required design occupant capacity for the storm shelter.
CRC § 423.1 High relevance — show source text
- A portable fire extinguisher shall be provided. Installation shall be in accordance with Section 906 and the extinguisher shall be located within a 30-foot (9144 mm) distance of travel from each domestic cooking appliance. 6. The area containing the domestic cooking appliances shall be separated from all other areas by fire partitions constructed complying with Section 708.
SECTION 423—STORM SHELTERS
423.1 General. This section applies to the design and construction of storm shelters constructed as separate detached buildings or constructed as rooms or spaces within buildings for the purpose of providing protection from tornadoes hurricanes and other severe windstorms during the storm. This section specifies where storm shelters are required and provides requirements for the design and construction of storm shelters. Design of facilities for use as emergency shelters after the storm are outside the scope of ICC 500 and shall comply with Table 1604.5 as a Risk Category IV Structure.
423.2 Construction. Storm shelters shall be constructed in accordance with this code and ICC 500 and shall be designated as hurricane shelters, tornado shelters, or combined hurricane and tornado shelters. Buildings or structures that are also designated as emergency shelters shall also comply with Table 1604.5 as Risk Category IV structures.
Any storm shelter not required by this section shall be permitted to be constructed, provided that such structures meet the requirements of this code and ICC 500.
423.3 Occupancy classification. The occupancy classification for a storm shelter shall be determined in accordance with this section.
423.3.1 Dedicated storm shelters. A facility designed to be occupied solely as a storm shelter shall be classified as Group A-3 for the determination of requirements other than those covered in ICC 500.
Exceptions:
The occupancy category for dedicated storm shelters with a design occupant capacity of less than 50 persons as determined in accordance with ICC 500 shall be in accordance with Section 303.
The occupancy category for a dedicated residential storm shelter shall be the Group R occupancy served.
423.3.2 Storm shelters within host buildings. Where designated storm shelters are constructed as a room or space within a host building that will normally be occupied for other purposes, the requirements of this code for the occupancy of the building, or the individual rooms or spaces thereof, shall apply unless otherwise required by ICC 500.
423.4 Critical emergency operations. In areas where the shelter design wind speed for tornados in accordance with Figure 304.2(1) of ICC 500 is 250 mph, 911 call stations, emergency operation centers and fire, rescue, ambulance and police stations shall comply with Table 1604.5 as a Risk Category IV structure and shall be provided with a storm shelter constructed in accordance with ICC 500.
423.4.1 Design occupant capacity. The required design occupant capacity of the storm shelter shall include the critical emergency operations on the site and shall be the total occupant load of offices and the number of beds.
Exceptions:
- Where approved by the building official, the actual number of occupants for whom each occupied space, floor or building is designed, although less than that determined by occupant load calculation, shall be permitted to be used in the determination of the required design occupant capacity for the storm shelter.
- Where a new building is being added on an existing site, and where the new building is not of sufficient size to accommodate the required design occupant capacity of the storm shelter for all of the buildings on the site, the storm shelter shall accommodate not less than the required occupant capacity of the new building.
CRC § 422.3.4 High relevance — show source text
422.3.4 Distance of travel. The distance of travel between any point in an ambulatory care facility and an exit shall be not greater than 200 feet (60 960 mm).
[F] 422.4 Automatic sprinkler systems. Automatic sprinkler systems shall be provided for ambulatory care facilities in accordance with Section 903.2.2.
[F] 422.5 Fire alarm systems. A fire alarm system shall be provided for ambulatory care facilities in accordance with Section 907.2.2.
[F] 422.6 Electrical systems. In ambulatory care facilities, the essential electrical system for electrical components, equipment and systems shall be designed and constructed in accordance with the provisions of Chapter 27 and California Electrical Code Article 517.
422.7 Domestic cooking. In fully sprinklered buildings, the installation of cooking appliances used in domestic cooking facilities shall comply with all of the following:
- The types of cooking appliances permitted are limited to ovens, cooktops, ranges, warmers and microwaves.
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SPECIAL DETAILED REQUIREMENTS BASED ON OCCUPANCY AND USE
- Domestic cooking hoods installed and constructed in accordance with Section 504.3 of the California Mechanical Code shall be provided over cooktops or ranges.
- A shutoff for the fuel and electrical supply to the cooking equipment shall be provided in a location to which only staff has
access.
A timer shall be provided that automatically deactivates the cooking appliances within a period of not more than 120 minutes.
A portable fire extinguisher shall be provided. Installation shall be in accordance with Section 906 and the extinguisher shall be located within a 30-foot (9144 mm) distance of travel from each domestic cooking appliance. 6. The area containing the domestic cooking appliances shall be separated from all other areas by fire partitions constructed complying with Section 708.
SECTION 423—STORM SHELTERS
423.1 General. This section applies to the design and construction of storm shelters constructed as separate detached buildings or constructed as rooms or spaces within buildings for the purpose of providing protection from tornadoes hurricanes and other severe windstorms during the storm. This section specifies where storm shelters are required and provides requirements for the design and construction of storm shelters. Design of facilities for use as emergency shelters after the storm are outside the scope of ICC 500 and shall comply with Table 1604.5 as a Risk Category IV Structure.
423.2 Construction. Storm shelters shall be constructed in accordance with this code and ICC 500 and shall be designated as hurricane shelters, tornado shelters, or combined hurricane and tornado shelters. Buildings or structures that are also designated as emergency shelters shall also comply with Table 1604.5 as Risk Category IV structures.
Any storm shelter not required by this section shall be permitted to be constructed, provided that such structures meet the requirements of this code and ICC 500.
423.3 Occupancy classification. The occupancy classification for a storm shelter shall be determined in accordance with this section.
423.3.1 Dedicated storm shelters. A facility designed to be occupied solely as a storm shelter shall be classified as Group A-3 for the determination of requirements other than those covered in ICC 500.
CRC § 1-31 High relevance — show source text
114 Stop Work Order . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-31
115 Unsafe Structures and Equipment . . . . . . . . . . . . . . 1-31
116 Emergency Measures . . . . . . . . . . . . . . . . . . . . . . . . . . 1-32
117 Demolition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-32
CHAPTER 2 DEFINITIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . .2-3
201 General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
202 General Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
CHAPTER 3 PROVISIONS FOR ALL COMPLIANCE
METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-3
301 Administration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
302 General Provisions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4
303 Storm Shelters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4
304 Structural Design Loads and Evaluation and Design Procedures. . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5
305 In-Situ Load Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6
306 Accessibility for Existing Buildings . . . . . . . . . . . . . . . 3-6
307 Smoke Alarms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6
308 Carbon Monoxide Detection . . . . . . . . . . . . . . . . . . . . . 3-6
309 Additions and Replacements of Exterior Wall Coverings and Exterior Wall Envelopes . . . . . . . . . 3-7
310 [OSHPD 1R, 2 and 5] Services/Systems and Utilities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7
311 [OSHPD 1R, 2 and 5] Means of Egress . . . . . . . . . . . . . . . 3-7
CRC § 1.1.6 High relevance — show source text
1.1.6 Nonbuilding standards, orders and regulations. Requirements contained in the International Residential Code, or in any other referenced standard, code or document, which are not building standards as defined in Health and Safety Code Section 18909, shall not be construed as part of the provisions of this code. For nonbuilding standards, orders and regulations, see other titles of the California Code of Regulations.
1.1.7 Order of precedence and use.
1.1.7.1 Differences. In the event of any differences between these building standards and the standard reference documents, the text of these building standards shall govern.
1.1.7.2 Specific provisions. Where a specific provision varies from a general provision, the specific provision shall apply.
1.1.7.3 Conflicts. When the requirements of this code conflict with the requirements of any other part of the California Building Stan- dards Code, Title 24, the most restrictive requirements shall prevail.
1.1.7.3.1 Detached one- and two-family dwellings. Detached one- and two-family dwellings, lodging houses, live/work units, townhouses not more than three stories above grade plane in height with a separate means of egress, and their accessory struc- tures may be designed and constructed in accordance with this code or the California Building Code, but not both, unless the proposed structure(s) or element(s) exceed the design limitations established in this code, and the code user is specifically directed by this code to use the California Building Code.
1.1.8 City, county, or city and county amendments, additions or deletions. The provisions of this code do not limit the authority of a city, county, or city and county governments to establish more restrictive and reasonably necessary differences to the provisions contained in this code pursuant to complying with Section 1.1.8.1. The effective date of amendments, additions or deletions to this code by a city, county, or city and county filed pursuant to Section 1.1.8.1 shall be the date filed. However, in no case shall the amendments, additions or deletions to this code be effective any sooner than the effective date of this code.
Local modifications shall comply with Health and Safety Code Section 18941.5 for Building Standards Law, Health and Safety Code Section 17958 for State Housing Law or Health and Safety Code Section 13869.7 for Fire Protection Districts.
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DIVISION I CALIFORNIA ADMINISTRATION
1.1.8.1 Findings and filings. 1. The city, county, or city and county shall make express findings for each amendment, addition or deletion based upon climatic, topographical or geological conditions.
Exception: Hazardous building ordinances and programs mitigating unreinforced masonry buildings. 2. The city, county, or city and county shall file the amendments, additions or deletions expressly marked and identified as to the applicable findings. Cities, counties, cities and counties and fire departments shall file the amendments, additions or deletions, and the findings with the California Building Standards Commission at 2525 Natomas Park Drive, Suite 130, Sacramento, CA 95833.
Frequently asked questions
Who is responsible for providing ICC 500 documents on a submittal?
The designer/permit applicant must provide the ICC/NSSA 500 design documents or show compliance with ICC 500 in the construction documents where the code requires a shelter (per § 303.1.1 / § 303.2).
If I build a voluntary (non‑required) shelter, do I still have to follow ICC 500?
Yes — the CBC and CEBC permit voluntary shelters, but they must meet the requirements of the code and ICC 500 when constructed as storm shelters (see CBC §423 and CEBC §303.1.1).
Does the 250 mph map come from the California code?
No — the 250 mph shelter‑design wind‑speed threshold referenced in § 303.2 is taken from ICC 500 Figure 304.2(1); the California code cites that ICC 500 figure as the trigger. Confirm the local classification in ICC 500 to know whether the 250 mph threshold applies.
Are Group E day care facilities always exempt from shelter requirements?
Group E day care facilities are listed as an exception in § 303.2 to the Group E addition requirement; verify the exact occupancy and local approvals because other California or local rules may apply.
If a building already has an existing shelter, can its capacity be credited?
Yes — § 303.2.1 permits the code official to approve reducing the required design occupant capacity of a new shelter by crediting the capacity of existing storm shelters on the site.
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