CBC · California Building Code

What flood and tsunami load provisions apply to structural design?

If your building is in an adopted flood hazard area the CBC requires flood‑resistant design per ASCE 7 (Ch.5) and ASCE 24 (§ 1612); if it’s a Risk Category III or IV building inside an ASCE Tsunami Design Zone the CBC requires tsunami load design per ASCE 7 (Ch.6) (§ 1615). Temporary public‑occupancy structures that meet controlled‑occupancy rules are excepted.

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Last reviewed: July 5, 2026

What the code requires — 2-4 sentences

New construction and substantial improvements located in mapped flood hazard areas must be designed to resist flood hazards in accordance with the referenced flood standards (ASCE 7, Chapter 5, and ASCE 24) as adopted by the CBC (§ 1612A.1–§ 1612A.2) . Buildings in Tsunami Design Zones that are classified as Risk Category III or IV must be designed for tsunami loads using ASCE 7, Chapter 6, except as modified by the CBC (§ 1615A.1) . Temporary public‑occupancy structures are excepted from these specific flood/tsunami design requirements if they meet the controlled‑occupancy/temporary‑structure rules (§ 3103.6.1.3 and § 3103.6.1.6) .

Requirements in detail

Scope and applicability

  • Who: All new construction, portions of buildings, and substantial improvements located in flood hazard areas (§ 1612A.1) .
  • Which flood/tsunami rules apply: Flood design follows Chapter 5 of ASCE 7 and ASCE 24; tsunami design for qualifying coastal projects follows Chapter 6 of ASCE 7 (with CBC modifications) (§ 1612A.2, § 1615A.1) .
  • Maps and elevations: Flood hazard areas and supporting data must be adopted by the governing authority (FEMA FIS/FIRM and any local revisions); where design flood elevations are not provided, the building official may require a professional determination (§ 1612A.3 and § 1612A.3.1) .

What to use for design (standards)

  • Flood loads: ASCE 7, Chapter 5, and ASCE 24 for flood‑resistant design and components (§ 1612A.2) .
  • Tsunami loads: ASCE 7, Chapter 6, for Risk Category III and IV buildings in ASCE Tsunami Design Zones; the ASCE Tsunami Design Geodatabase is an accepted source for defining those zones (§ 1615A.1) .
  • Elevation/control: Use adopted flood hazard maps (FIRM) or professional hydrologic/hydraulic analysis when maps don’t provide design elevations (§ 1612A.3.1) .

Decision‑relevant dimensions / values

Decision item Typical value or trigger Code reference
Which projects require flood design? All new construction and substantial improvements in adopted flood hazard areas § 1612A.1
Design standards for flood‑resistance ASCE 7, Ch. 5 and ASCE 24 (elevations, openings, flotation, hydrostatic and hydrodynamic loads) § 1612A.2
Who decides flood hazard maps? Governing authority must adopt maps (FEMA FIS/FIRM etc.) § 1612A.3
When must a registered professional determine BFE? When design flood elevations are not included on adopted maps § 1612A.3.1
Which buildings need tsunami design? Risk Category III and IV buildings/structures in Tsunami Design Zones § 1615A.1
Temporary public‑occupancy structures May be excepted from flood/tsunami design if they comply with controlled‑occupancy temporary rules § 3103.6.1.3 and § 3103.6.1.6

Exceptions & special cases

  • Temporary public‑occupancy structures: The CBC permits omission of the flood loads in § 1612 and tsunami loads in § 1615 for temporary public‑occupancy structures that comply with the special procedures in Section 3103.6 (controlled occupancy and operations plan) (§ 3103.6.1.3 and § 3103.6.1.6) .
  • Multiple hazard areas: Where a building lies in more than one flood hazard area, the most restrictive provisions apply (§ 1612A.1) .
  • Missing BFEs: If the adopted map lacks design flood elevations or a floodway, the building official may require a registered design professional to determine them using accepted hydrologic/hydraulic practice (§ 1612A.3.1) .
  • Jurisdictional modifications and local data: The CBC allows the use of ASCE Tsunami Design Geodatabase or other data determined applicable by the enforcement agency to define tsunami zones (§ 1615A.1) .

Common mistakes

  • Designing for tsunami loads when it is not required: tsunami provisions in § 1615A.1 apply only to Risk Category III/IV buildings located in Tsunami Design Zones; not every coastal building is automatically subject to Chapter 6 of ASCE 7 .
  • Relying on outdated or unadopted maps: the governing authority must adopt flood hazard maps; designers should confirm the local adopted FIRM/FIS or locally adopted maps per § 1612A.3 .
  • Treating the CBC as prescribing the calculation method for hydrodynamic/debris loads: the CBC mandates the referenced ASCE chapters (ASCE 7 & ASCE 24) for calculation methods; do not substitute different methods without approval (§ 1612A.2, § 1615A.1) .
  • Forgetting the “most restrictive” rule: when a project overlaps multiple flood designations, the stricter requirement governs (§ 1612A.1) .
  • Neglecting to document professional determinations: when BFEs or floodways are developed by a registered design professional, the code expects documentation of accepted engineering practice (§ 1612A.3.1) .

Worked example — coastal hospital (concrete steps, numbers illustrative)

Scenario: New hospital (Risk Category IV) sited on a coastal lot. The adopted local flood hazard map (FIRM) shows a Base Flood Elevation (BFE) of 12.0 ft (NAVD88). The site also falls inside the ASCE Tsunami Design Zone.

Steps to apply CBC requirements (with references):

  1. Confirm applicability:

    • Flood: site lies in an adopted flood hazard area → flood rules apply (§ 1612A.1) .
    • Tsunami: Risk Category IV in Tsunami Design Zone → tsunami design required (§ 1615A.1) .

  2. Select standards:

    • Flood design per ASCE 7, Chapter 5 and ASCE 24 (§ 1612A.2) .
    • Tsunami design per ASCE 7, Chapter 6 (§ 1615A.1) .

  3. Elevation control (example numeric decision):

    • Use the adopted BFE = 12.0 ft as the starting design flood elevation (per § 1612A.3). The CBC requires use of adopted flood hazard data or a professional determination when absent (§ 1612A.3 & § 1612A.3.1) .
    • Practically, you will set the hospital’s lowest occupied floor elevation to meet or exceed the required elevation per ASCE 24 (the CBC delegates the elevation/detail rules to ASCE 24 via § 1612A.2) — compute exact finished‑floor elevation and required floodproofing in accordance with ASCE 24 and local requirements (§ 1612A.2) .

  4. Tsunami load design (conceptual steps):

    • Use ASCE 7, Chapter 6 procedures to compute tsunami hydrodynamic, hydrostatic and debris impact loads; include tsunami vertical evacuation considerations where applicable. Because the CBC explicitly requires ASCE 7 Chapter 6 for Risk Category IV in Tsunami Design Zones, those computed loads must be included in structural load combinations (§ 1615A.1) .
    • Coordinate tsunami load effects with other load combinations per Chapter 16 provisions (load combinations are implemented per CBC/ASCE requirements).

Note: the CBC points you to the ASCE standards for the computational details (ASCE 7 and ASCE 24); those standards contain the formulas, coefficients and load combination details necessary to produce the numeric design forces — the CBC itself sets applicability, mapping and referenced standards (§ 1612A.1–§ 1612A.3.1, § 1615A.1) .

Related provisions

  • § 1612A.1–§ 1612A.3.1 — Flood loads and establishment of flood hazard areas (use adopted maps or RDP determination) .
  • § 1615A.1 — Tsunami loads: Risk Category III & IV in Tsunami Design Zones follow ASCE 7, Ch. 6 (CBC modifications possible) .
  • § 3103.6.1.3 and § 3103.6.1.6 — Temporary public‑occupancy structures exception for flood and tsunami design if they comply with controlled‑occupancy rules .
  • Appendix G (Flood‑Resistant Construction) — administrative and NFIP‑related provisions (adopt where applicable) § G101 et seq. .
  • Appendix M (Tsunami‑Generated Flood Hazards) — guidance for vertical evacuation refuge structures (optional adoption) § M101 et seq. .
  • CBC Chapter 16 load combination and load application provisions (see general load and construction document requirements in Chapters 16/16A) for how to combine flood/tsunami loads with other loads (§ 1603–1605) .

Code references

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

  • CBC § 31-5 High relevance — show source text

    2025 CALIFORNIA BUILDING CODE 31-5

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

    SPECIAL CONSTRUCTION

    1. For public-occupancy temporary structures erected in a hurricane-prone region outside of hurricane season, the basic wind speed, V, shall be permitted to be set as follows, depending on risk category: 2.1. Risk Category II: 115 mph. 2.2. Risk Category III: 120 mph. 2.3. Risk Category IV: 125 mph.
    TABLE 3103.6.1.2—REDUCTION FACTORS FOR WIND LOADS FOR PUBLIC-OCCUPANCY TEMPORARY STRUCTURES Col2 Col3
    RISK CATEGORY SERVICE LIFE SERVICE LIFE
    RISK CATEGORY ≤ 10 yr >10 yr
    II 0.8 1.0
    III 0.9 1.0
    IV 1.0 1.0

    3103.6.1.3 Flood loads. Public-occupancy temporary structures need not be designed for flood loads specified in Section 1612. Controlled occupancy procedures in accordance with Section 3103.8 shall be implemented.

    3103.6.1.4 Seismic loads. Seismic loads on public-occupancy temporary structures assigned to Seismic Design Categories C through F shall be permitted to be taken as 75 percent of those determined by Section 1613. Public-occupancy temporary structures assigned to Seismic Design Categories A and B are not required to be designed for seismic loads.

    3103.6.1.5 Ice loads. Ice loads on public-occupancy temporary structures shall be permitted to be determined with a maximum nominal thickness of 0.5 inch (13 mm), for all risk categories. Where the public-occupancy temporary structure is not subject to ice loads or not constructed and occupied during times when ice is to be expected, ice loads need not be considered, provided that where the period of time when the public-occupancy temporary structure is in service shifts to include times when ice is to be expected, one of the following conditions is met:

    1. The design is reviewed and modified, as appropriate, to account for ice loads.
    2. Controlled occupancy procedures in accordance with Section 3103.8 are implemented.

    3103.6.1.6 Tsunami loads. Public-occupancy temporary structures in a tsunami design zone are not required to be designed for tsunami loads specified in Section 1615. Controlled occupancy procedures in accordance with Section 3103.8 shall be implemented.

    3103.6.2 Foundations. Public-occupancy temporary structures shall be permitted to be supported on the ground with temporary foundations where approved by the building official. Consideration shall be given for the impacts of differential settlement where foundations do not extend below the ground or where foundations are supported on compressible materials. The presumptive load-bearing value for public-occupancy temporary structures supported on a pavement, slab on grade or on other collapsible or controlled low-strength substrate soils such as beach sand or grass shall be assumed not to exceed 1,000 pounds per square foot (47.88 kPa) unless determined through testing and evaluation by a registered design professional. The presumptive load-bearing values listed in Table 1806.2 shall be permitted to be used for other supporting soil conditions.

  • CBC § 16-33 High relevance — show source text

    1612 Flood Loads. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16-33

    1613 Earthquake Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . .16-34

    1614 Atmospheric Ice Loads . . . . . . . . . . . . . . . . . . . . . . . .16-36

    1615 Tsunami Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16-36

    1616 Structural Integrity . . . . . . . . . . . . . . . . . . . . . . . . . . .16-36

    1617 Additional Requirements for Community Colleges [DSA-SS/CC] . . . . . . . . . . . . . 16-38

    CHAPTER 16A STRUCTURAL DESIGN. . . . . . . . . . . . . . . . . 16A-1

    1601A General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16A-3

    1602A Notations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16A-3

    1603A Construction Documents . . . . . . . . . . . . . . . . . . . . . . . 16A-4

    1604A General Design Requirements. . . . . . . . . . . . . . . . . . . 16A-5

    1605A Load Combinations . . . . . . . . . . . . . . . . . . . . . . . . . . . 16A-10

    1606A Dead Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16A-10

    1607A Live Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16A-11

    1608A Snow Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16A-19

    1609A Wind Loads. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16A-24

    1610A Soil Loads and Hydrostatic Pressure. . . . . . . . . . . . 16A-31

    1611A Rain Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16A-32

    1612A Flood Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16A-33

  • CBC § 2109.2.4.9 High relevance — show source text

    Adobe 2109.2.4.9

    Fire resistance 704.10 Masonry, wood support 2304.13 Liquefied Petroleum Gas Table 414.5.1,

    415.9.2 Listed (definition) 202 Listing Agency (definition) 202 Live Load 1607

    Construction Documents 1603.1.1

    Posting of 106.1 Roof 1607

    Live/Work Units 310.3, 508.5 Accessibility Chapters 11A and 11B Separation 508.2 Load and Resistance Factor Design (LRFD) 1602.1

    Factored load 1604.2

    Limit state 1604.2

    Load combinations 1605 Wood design 2302.1, 2307 Load Combinations 1605 Allowable stress design 1605, 1605.2 Alternative allowable stress load

    combinations 1605.2 Load and resistance factor design 1605 Strength design 1605 Loads 106, 202 Atmospheric ice 1614 Combinations 1605

    Dead 1606

    Factored load 402.8.2.1, 1604.2,

    1709.2

    Flood 1603.1.7, 1612 Impact 1607.12 Live 508.5.8, 1603.1.1, 1607 Load effects 1604.4

    Nominal load 1604.2 Partial loading 1607.3.1, 1607.3.2 Rain 1603.1.9, 1611 Seismic 1603.1.5, 1613 Snow 1603.1.3, 1608 Soil lateral 1610

    Tornado 1603.1.4, 1609.5, 1609.6.3.2 Tsunami 1615

    Wind 1603.1.4, 1609 Lobbies Assembly occupancy 1030.4 Elevator 405.4.3, 1009.2.1, 1009.4, 3006, 3007.6, 3008.6 Exit discharge 1028.2 Underground buildings 405.4.3 Lobby 202 Local Enforcing Agency 1.8.3 Locks and Latches 1010.2, 1010.2.8 Delayed egress locks 1010.2.12 Electromagnetically locked 1010.2.10 Fire Exit Hardware 1010.2.10, 1010.2.8 Group I-2 407.4.1.1, 1010.2.13 Group I-3 408.4 High-rise 403.5.3 Sensor release 1010.2.11

    Toilet rooms Chapter 29 Lodging Houses 310.4, 310.4.2 Lowest Floor 1603.1.7, 1612.4 Lumber

    General provisions Chapter 23 Quality standards 2303

  • CBC § 13.6.12. High relevance — show source text
    1. Determined in accordance with ASCE 7.

    Where Site Class DE, E or F soils are present, the seismic design category shall be determined in accordance with ASCE 7.

    1613 A .3 Simplified design procedure. Not permitted by DSA-SS and OSHPD.

    1613 A .4 Ballasted photovoltaic panel systems. Ballasted, roof-mounted photovoltaic panel systems need not be rigidly attached to the roof or supporting structure.

    [DSA-SS] Ballasted, roof-mounted photovoltaic panel systems shall comply with ASCE 7, Section 13.6.12. [OSHPD 1 & 4] Ballasted photovoltaic panel systems shall be considered as an alternative system.

    1613 A .5 Elevators, escalators and other conveying systems. Elevators, escalators and other conveying systems and their components shall satisfy the seismic requirements of ASCE 7 and ASME A17.1/CSA B44 as applicable.

    1613 A .6 Automatic sprinkler systems. Where required, automatic sprinkler systems, including anchorage and bracing, shall comply with ASCE 7 and Section 903.3.1.1.

    SECTION 1614 A —ATMOSPHERIC ICE LOADS

    1614 A .1 General. Ice-sensitive structures shall be designed for atmospheric ice loads in accordance with Chapter 10 of ASCE 7.

    Exception: Temporary structures complying with Section 3103.6.1.5.

    SECTION 1615 A —TSUNAMI LOADS

    1615 A .1 General. The design and construction of Risk Category III and IV buildings and structures located in the Tsunami Design Zones defined in the ASCE Tsunami Design Geodatabase, or other data determined applicable by the enforcement agency, shall be in accordance with Chapter 6 of ASCE 7, except as modified by this code. [DSA-SS] Tsunami Risk Category for public school, community college and state-owned or state-leased essential services buildings and structures shall be identified and submitted for acceptance by DSA. Determination of the Tsunami Risk Category shall be proposed by the design professional in general responsible charge in coordi- nation with the owner and local community based upon the relative importance of that facility to provide vital services, provide important functions and protect special populations. The determination of relative importance shall include consideration of a tsunami warning and evacuation plan and procedure when adopted by the local community.

    Exception: Temporary structures complying with Section 3103.6.1.6.

    SECTION 1616 A —STRUCTURAL INTEGRITY

    1616 A .1 General. High-rise buildings that are assigned to Risk Category III or IV shall comply with the requirements of Section 1616 A .2 if they are frame structures, or Section 1616 A .3 if they are bearing wall structures.

    1616 A .2 Frame structures. Frame structures shall comply with the requirements of this section.

  • CBC § 1614.1 High relevance — show source text

    SECTION 1614—ATMOSPHERIC ICE LOADS

    1614.1 General. Ice-sensitive structures shall be designed for atmospheric ice loads in accordance with Chapter 10 of ASCE 7.

    Exception: Temporary structures complying with Section 3103.6.1.5.

    SECTION 1615—TSUNAMI LOADS

    1615.1 General. The design and construction of Risk Category III and IV buildings and structures located in the Tsunami Design Zones defined in the Tsunami Design Geodatabase shall be in accordance with Chapter 6 of ASCE 7, except as modified by this code.

    Exception: Temporary structures complying with Section 3103.6.1.6.

    SECTION 1616—STRUCTURAL INTEGRITY

    1616.1 General. High-rise buildings that are assigned to Risk Category III or IV shall comply with the requirements of Section 1616.2 if they are frame structures, or Section 1616.3 if they are bearing wall structures.

    1616.2 Frame structures. Frame structures shall comply with the requirements of this section.

    1616.2.1 Concrete frame structures. Frame structures constructed primarily of reinforced or prestressed concrete, either castin-place or precast, or a combination of these, shall conform to the requirements of Section 4.10 of ACI 318. Where ACI 318 requires that nonprestressed reinforcing or prestressing steel pass through the region bounded by the longitudinal column reinforcement, that reinforcing or prestressing steel shall have a minimum nominal tensile strength equal to two-thirds of the required one-way vertical strength of the connection of the floor or roof system to the column in each direction of beam or slab reinforcement passing through the column.

    Exception: Where concrete slabs with continuous reinforcement having an area not less than 0.0015 times the concrete area in each of two orthogonal directions are present and are either monolithic with or equivalently bonded to beams, girders or columns, the longitudinal reinforcing or prestressing steel passing through the column reinforcement shall have a nominal tensile strength of one-third of the required one-way vertical strength of the connection of the floor or roof system to the column in each direction of beam or slab reinforcement passing through the column.

    1616.2.2 Structural steel, open web steel joist or joist girder, or composite steel and concrete frame structures. Frame structures constructed with a structural steel frame or a frame composed of open web steel joists, joist girders with or without other structural steel elements or a frame composed of composite steel or composite steel joists and reinforced concrete elements shall conform to the requirements of this section.

    1616.2.2.1 Columns. Each column splice shall have the minimum design strength in tension to transfer the design dead and live load tributary to the column between the splice and the splice or base immediately below.

    1616.2.2.2 Beams. End connections of all beams and girders shall have a minimum nominal axial tensile strength equal to the required vertical shear strength for allowable stress design (ASD) or two-thirds of the required shear strength for load and resistance factor design (LRFD) but not less than 10 kips (45 kN). For the purpose of this section, the shear force and the axial tensile force need not be considered to act simultaneously.

  • CBC § 1617.8 High relevance — show source text

    Exception: This story drift limit need not be applied for single-story open structures in Risk Categories I and II.

    1617.8 Soil loads.

    1617.8.1 Lateral pressures. Structures below grade shall be designed to resist lateral soil loads from adjacent soil in accordance with Sections 1807A.1.1 and 1807A.2.2, respectively.

    Note: Sections 1807A.1.1 and 1807A.2.2 require the foundation and retaining walls be designed using the lateral soil loads deter- mined by a geotechnical investigation in accordance with Section 1803A. Section 1807A.2.2 requires that design lateral soil load be at least 80 percent of the design lateral soil loads in accordance with Table 1610.1.

    1617.9 Flood loads.

    1617.9.1 Establishment of flood hazard areas. Flood hazard maps shall include, at a minimum, areas of special flood hazard as identified by the Federal Emergency Management Agency's Flood Insurance Study (FIS) adopted by the local authority having juris- diction where the project is located, as amended or revised with the accompanying Flood Insurance Rate Map (FIRM) and Flood Boundary and Floodway Map (FBFM) and related supporting data along with any revisions thereto.

    1617.10 Earthquake loads.

    1617.10.1 Determination of seismic design category. The seismic design category for a structure shall be determined in accor- dance with Section 1613.2. Seismic design category shall be D or higher.

    1617.10.2 Simplified design procedure. The simplified design procedure of Section 1613.3 is not permitted by DSA-SS/CC.

    1617.10.3 Ballasted photovoltaic panel systems. Ballasted, roof-mounted photovoltaic panel systems shall comply with ASCE 7, Section 13.6.12.

    1617.11 Tsunami loads. The design and construction of Risk Category III or IV buildings and structures located in the ASCE Tsunami Design Zones defined in the ASCE Tsunami Design Geodatabase, or other data determined applicable by the enforcement agency, shall be in accordance with Section 1615.1 except as modified by this code. Tsunami Risk Category for community college buildings and struc- tures shall be identified and submitted for acceptance by DSA. Determination of Tsunami Risk Category shall be proposed by the design professional in general responsible charge in coordination with the owner and local community based upon the relative importance of that facility to provide vital services, provide important functions and protect special populations. The determination of relative impor- tance shall include consideration of a tsunami warning and evacuation plan and procedure when adopted by the local community.

    1617.12 Modifications to ASCE 7. The text of ASCE 7 shall be modified as indicated in Sections 1617.12.1 through 1617.12.19.

    1617.12.1 ASCE 7, Section 1.3. Modify ASCE 7, Section 1.3 by adding Section 1.3.8 as follows:

  • CBC § M101 High relevance — show source text

    2025 CALIFORNIA BUILDING CODE APPENDIX M-1

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

    M TSUNAMI-GENERATED FLOOD HAZARDS

    The provisions contained in this appendix are not mandatory unless specifically adopted by a state agency or referenced in the adopting ordinance.

    User notes:

    About this appendix: Appendix M allows the adoption of guidelines for constructing vertical evacuation refuge structures within areas that are considered tsunami hazard zones.

    ICC code development note: Code change proposals to this appendix will be considered by the IBC—Structural Code Development Committee during the

    2025 (Group B) Code Development Cycle.

    SECTION M101—REFUGE STRUCTURES FOR VERTICAL EVACUATION FROM TSUNAMI-GENERATED FLOOD HAZARDS

    M101.1 General. The purpose of this appendix is to provide tsunami vertical evacuation planning criteria for those coastal communities that have a tsunami hazard as shown in a Tsunami Design Zone Map.

    M101.2 Definitions. The following term shall, for the purposes of this appendix, have the meaning shown herein. Refer to Chapter 2 of this code for general definitions.

    TSUNAMI DESIGN ZONE MAP. A map that designates the extent of inundation by a Maximum Considered Tsunami, as defined by Chapter 6 of ASCE 7.

    M101.3 Establishment of tsunami design zone. Where applicable, the Tsunami Design Zone Map shall meet or exceed the inundation limit given by the ASCE 7 Tsunami Design Geodatabase .

    M101.4 Planning of tsunami vertical evacuation refuge structures within the tsunami design zone. Tsunami Vertical Evacuation Refuge Structures located within a tsunami hazard design zone shall be planned, sited, and developed in general accordance with the planning criteria of the FEMA P646 guidelines.

    Exception: These criteria shall not be considered mandatory for evaluation of existing buildings for evacuation planning

    purposes.

    SECTION M102—REFERENCED STANDARDS

    M102.1 General. See Table M102.1 for standards that are referenced in various sections of this appendix. Standards are listed by the standard identification with the effective date, standard title, and the section or sections of this appendix that reference the standard.

    TABLE M102.1—REFERENCED STANDARDS Col2 Col3
    STANDARD ACRONYM STANDARD NAME SECTIONS HEREIN REFERENCED
    ASCE 7—22 Minimum Design Load and Associated Criteria for Buildings and Other Structures M101.2, M101.3
    FEMA P646—12 Guidelines for Design of Structures for Vertical Evacuation from Tsunamis M101.4

    APPENDIX M-2 2025 CALIFORNIA BUILDING CODE

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

    CALIFORNIA BUILDING CODE – MATRIX ADOPTION TABLE

    APPENDIX N – REPLICABLE BUILDINGS

    (Not adopted by state agencies)

  • CBC § 1604.2 High relevance — show source text

    Nominal load 1604.2 Partial loading 1607.3.1, 1607.3.2 Rain 1603.1.9, 1611 Seismic 1603.1.5, 1613 Snow 1603.1.3, 1608 Soil lateral 1610

    Tornado 1603.1.4, 1609.5, 1609.6.3.2 Tsunami 1615

    Wind 1603.1.4, 1609 Lobbies Assembly occupancy 1030.4 Elevator 405.4.3, 1009.2.1, 1009.4, 3006, 3007.6, 3008.6 Exit discharge 1028.2 Underground buildings 405.4.3 Lobby 202 Local Enforcing Agency 1.8.3 Locks and Latches 1010.2, 1010.2.8 Delayed egress locks 1010.2.12 Electromagnetically locked 1010.2.10 Fire Exit Hardware 1010.2.10, 1010.2.8 Group I-2 407.4.1.1, 1010.2.13 Group I-3 408.4 High-rise 403.5.3 Sensor release 1010.2.11

    Toilet rooms Chapter 29 Lodging Houses 310.4, 310.4.2 Lowest Floor 1603.1.7, 1612.4 Lumber

    General provisions Chapter 23 Quality standards 2303

    Mail Receptacles, Locking 420.13.1 Maintenance Means of egress 1002.1, 3310.2 Property 101.4.4 Mall (see Covered Mall and Open Mall Buildings) Manual Fire Alarm Box 907.4.2

    Manufactured Homes

    Flood resistant G109

    2025 CALIFORNIA BUILDING CODE INDEX-13

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

    INDEX

    Veneer 1403.5, 1404.12 Metal Building System 1705.2.8, Table 1705.2.6, 2210 Metal Composite Material (MCM) 1406 Metal Roof Panel 1504.4.2, 1507.1.1, 1507.4,

    1512.3 Metal Roof Shingle 1504.4.3, 1507.1.1, 1507.5, 1507.5.7, 1512.3 Mezzanines 505 Accessibility Chapters 11A and 11B Area limitations 505.2.1, 505.2.1.1,

    505.3.1

  • CBC § 1613.3 High relevance — show source text

    STRUCTURAL DESIGN

    1613.3 Simplified design procedure. Where the alternate simplified design procedure of ASCE 7 is used, the seismic design category shall be determined in accordance with ASCE 7.

    1613.4 Ballasted photovoltaic panel systems. Ballasted, roof-mounted photovoltaic panel systems need not be rigidly attached to the roof or supporting structure. Ballasted, unattached PV panel systems shall be designed and installed only on roofs with slopes not more than 1 unit vertical in 12 units horizontal. Ballasted, unattached PV panel systems shall be designed to accommodate sliding in accordance with ASCE 7 Chapter 13. [OSHPD 1R, 2 & 5] Ballasted photovoltaic panel systems shall be considered as an alternative system.

    1613.5 Elevators, escalators and other conveying systems. Elevators, escalators and other conveying systems and their components shall satisfy the seismic requirements of ASCE 7 and ASME A17.1/CSA B44 as applicable.

    1613.6 Automatic sprinkler systems. Where required, automatic sprinkler systems, including anchorage and bracing, shall comply with ASCE 7 and Section 903.3.1.1.

    1613.7 Component importance factors. [OSHPD 1R, 2 & 5] Nonstructural components designated below shall have a component importance factor, I p , equal to 1.5: 1. For components that are required for life-safety purposes after an earthquake, including emergency and standby power systems, mechanical smoke removal systems, fire protection sprinkler systems and fire alarm control panels. 2. For medical equipment required for patient life support.

    SECTION 1614—ATMOSPHERIC ICE LOADS

    1614.1 General. Ice-sensitive structures shall be designed for atmospheric ice loads in accordance with Chapter 10 of ASCE 7.

    Exception: Temporary structures complying with Section 3103.6.1.5.

    SECTION 1615—TSUNAMI LOADS

    1615.1 General. The design and construction of Risk Category III and IV buildings and structures located in the Tsunami Design Zones defined in the Tsunami Design Geodatabase shall be in accordance with Chapter 6 of ASCE 7, except as modified by this code.

    Exception: Temporary structures complying with Section 3103.6.1.6.

    SECTION 1616—STRUCTURAL INTEGRITY

    1616.1 General. High-rise buildings that are assigned to Risk Category III or IV shall comply with the requirements of Section 1616.2 if they are frame structures, or Section 1616.3 if they are bearing wall structures.

    1616.2 Frame structures. Frame structures shall comply with the requirements of this section.

    1616.2.1 Concrete frame structures. Frame structures constructed primarily of reinforced or prestressed concrete, either castin-place or precast, or a combination of these, shall conform to the requirements of Section 4.10 of ACI 318. Where ACI 318 requires that nonprestressed reinforcing or prestressing steel pass through the region bounded by the longitudinal column reinforcement, that reinforcing or prestressing steel shall have a minimum nominal tensile strength equal to two-thirds of the required one-way vertical strength of the connection of the floor or roof system to the column in each direction of beam or slab reinforcement passing through the column.

  • CBC § 3.1 High relevance — show source text

    Appendix G Flood-Resistant Construction.

    Appendix G is intended to fulfill the flood-plain management and administrative requirements of the National Flood Insurance Program (NFIP) that are not included in the code. Communities that adopt the IBC and Appendix G will meet the minimum requirements of NFIP as set forth in Title 44 of the Code of Federal Regulations.

    Appendix H Signs.

    Appendix H gathers in one place the various code standards that regulate the construction and protection of outdoor signs.

    Appendix I Patio Covers.

    Appendix I provides standards applicable to the construction and use of patio covers. It is limited in application to patio covers accessory to dwelling units. Covers of patios and other outdoor areas associated with restaurants, mercantile buildings, offices, nursing homes or other nondwelling occupancies would be subject to standards in the main code and not this appendix.

    Appendix J Grading.

    Appendix J provides standards for the grading of properties. This appendix also provides standards for administration and enforcement of a grading program including permit and inspection requirements.

    Appendix K Group R-3 and Group R-3.1 Occupancies Protected by the Facilities of the Central Valley Flood Protection Plan.

    Appendix K provides provisions applicable to new construction, changes of use and to substantial improvement and restoration of substantial damage as defined in Section 1612 of Groups R-3 and R-3.1 located in areas protected by the facilities of the Central Valley Flood Protection Plan.

    Appendix L Earthquake Recording Instrumentation.

    The purpose of Appendix L is to foster the collection of ground motion data, particularly from strong-motion earthquakes. When this ground motion data is synthesized, it may be useful in developing future improvements to the earthquake provisions of the CBC.

    Appendix M Tsunami-Generated Flood Hazards.

    Addressing a tsunami risk for all types of construction in a tsunami hazard zone through building code requirements would typically not be cost effective, making tsunami-resistant construction impractical at an individual building level. However, Appendix M does allow the adoption and enforcement of requirements for tsunami hazard zones that regulate the presence of high-risk or high-hazard structures.

    Appendix N Replicable Buildings.

    Appendix N provides jurisdictions with a means of incorporating replicable building requirements contained in the ICC G1-2010, Guideline for Replicable Buildings, into their building code adoption process. The intent is to streamline the plan review process at the local level by removing redundant reviews.

    Appendix O Performance-Based Application.

    Appendix O provides an optional design, review and approval framework for use by the building official. It extracts relevant administrative provisions from the International Code Council Performance Code ® for Buildings and Facilities (ICCPC®) into a more concise, usable appendix format for a jurisdiction confronted with such a need.

    xviii 2025 CALIFORNIA BUILDING CODE

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    Appendix P Sleeping Lofts.

    Appendix P provides allowances for, and limitations on, spaces intended to be used as sleeping lofts, while differentiating these spaces from mezzanines and other habitable spaces.

    Appendix Q Emergency Housing .

    This appendix shall be applicable to emergency housing and emergency housing facilities. Emergency sleeping cabins, emergency transportable housing units, membrane structures and tents constructed and assembled in accordance with this appendix shall be occupied only during declaration of state of emergency, local emergency or shelter crises. Buildings and structures constructed in accor- dance with the California Building Code, used as emergency housing, shall be permitted to be permanently occupied.

  • CBC § 5A-4 High relevance — show source text

    5A-4 2025 CALIFORNIA EXISTING BUILDING CODE

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

    PRESCRIPTIVE COMPLIANCE METHOD

    the requirements for new construction for flood design. For new foundations, foundations raised or extended upward, and replacement foundations, the foundations shall be in compliance with the requirements for new construction for flood design.

    For buildings and structures in flood hazard areas established in California Building Code, Section 1612 A .3, any additions that do not constitute substantial improvement of the existing structure , as defined in Chapter 2, are not required to comply with the flood design requirements for new construction, provided that both of the following apply:

    1. The addition shall not create or extend a nonconformity of the existing building or structure with the flood-resistant construction requirements.
    2. The lowest floor of the addition shall be at or above the lower of the lowest floor of the existing building or structure or the lowest floor elevation required in Section 1612 A of the California Building Code .

    502 A .3 Existing structural elements carrying gravity load. Any existing gravity load-carrying structural element for which an addition and its related alterations cause an increase in design dead, live or snow load, including snow drift effects, of more than 5 percent shall be replaced or altered as needed to carry the gravity loads required by the California Building Code for new structures. Any existing gravity load-carrying structural element whose vertical load-carrying capacity is decreased as part of the addition and its related alterations shall be considered to be an altered element subject to the requirements of Section 503 A .3. Any existing element that will form part of the lateral load path for any part of the addition shall be considered to be an existing lateral load-carrying structural element subject to the requirements of Section 502A.4 .

    502 A .4 Existing structural elements carrying lateral load. Where the addition is structurally independent of the existing structure, existing lateral load-carrying structural elements shall be permitted to remain unaltered. Where the addition is not structurally independent of the existing structure, the lateral force-resisting system of the existing structure and its addition acting together as a single structure shall comply with Section 1609 A and 1613A of the California Building Code .

    Exceptions: For incidental and minor additions:

    1. Any existing lateral load-carrying structural element whose demand-capacity ratio with the addition considered is not more than 10 percent greater than its demand-capacity ratio with the addition ignored shall be permitted to remain unaltered. For purposes of calculating demand-capacity ratios, the demand shall consider applicable load combinations with design lateral loads or forces in accordance with Sections 1609 A and 1613 A of the California Building Code . For purposes of this exception, comparisons of demand-capacity ratios and calculation of design lateral loads, forces and capacities shall account for the cumulative effects of additions and alterations since original construction. When calculating demand-capacity ratios for wind, the date of original construction shall be permitted to be taken as the date of completion of a prior addition, alteration or repair in compliance with Section 1609 A of the California Building Code or the code wind forces in effect at the time.
  • CBC § 1611A.1 High relevance — show source text
    TABLE 1611A.1—DESIGN STORM RETURN PERIOD BY RISK CATEGORY Col2
    RISK CATEGORY DESIGN STORM RETURN PERIOD
    I & II 100 years
    III 200 years
    IV 500 years

    1611 A .2 Ponding instability. Ponding instability on roofs shall be evaluated in accordance with ASCE 7.

    1611 A .3 Controlled drainage. Roofs equipped with hardware to control the rate of drainage shall be equipped with a secondary drainage system at a higher elevation that limits accumulation of water on the roof above that elevation. Such roofs shall be designed to sustain the load of rainwater that will accumulate on them to the elevation of the secondary drainage system plus the uniform load caused by water that rises above the inlet of the secondary drainage system at its design flow determined from Section 1611 A .1. Such roofs shall be checked for ponding instability in accordance with Section 1611 A .2.

    SECTION 1612 A —FLOOD LOADS

    1612 A .1 General. Within flood hazard areas as established in Section 1612 A .3, all new construction of buildings, structures and portions of buildings and structures, including substantial improvement and restoration of substantial damage to buildings and structures, shall be designed and constructed to resist the effects of flood hazards and flood loads. For buildings that are located in more than one flood hazard area, the provisions associated with the most restrictive flood hazard area shall apply.

    1612 A .2 Design and construction. The design and construction of buildings and structures located in flood hazard areas, including coastal high hazard areas and coastal A zones, shall be in accordance with Chapter 5 of ASCE 7 and ASCE 24. Elevators, escalators, conveying systems and their components shall conform to ASCE 24 and ASME A17.1/CSA B44 as applicable.

    Exception: Temporary structures complying with Section 3103.6.1.3.

    1612 A .3 Establishment of flood hazard areas. To establish flood hazard areas, the applicable governing authority shall adopt a flood hazard map and supporting data. The flood hazard map shall include, at a minimum, areas of special flood hazard as identified by the Federal Emergency Management Agency’s Flood Insurance Study (FIS) adopted by the local authority having jurisdiction where the project is located, as amended or revised with the accompanying Flood Insurance Rate Map ( FIRM ) and Flood Boundary and Flood- way Map (FBFM) and related supporting data along with any revisions thereto. The adopted flood hazard map and supporting data are hereby adopted by reference and declared to be part of this section.

    1612 A .3.1 Design flood elevations. Where design flood elevations are not included in the flood hazard areas established in Section 1612 A .3, or where floodways are not designated, the building official is authorized to require the applicant to do one of the following:

    1. Obtain and reasonably utilize any design flood elevation and floodway data available from a federal, state or other

    source.

    1. Determine the design flood elevation or floodway in accordance with accepted hydrologic and hydraulic engineering practices used to define special flood hazard areas. Determinations shall be undertaken by a registered design professional who shall document that the technical methods used reflect currently accepted engineering practice.

Frequently asked questions

Do all coastal buildings need tsunami load design?

No. The CBC requires tsunami load design only for Risk Category III and IV buildings and structures located in the ASCE Tsunami Design Zones; other coastal buildings are not automatically covered by § 1615A.1 unless the local enforcement agency applies additional criteria .

Where do I get the flood elevation (BFE) to design to?

Use the adopted flood hazard map and supporting data (FEMA FIS/FIRM) adopted by the governing authority. If the adopted map does not include a design flood elevation or floodway, the building official can require a registered design professional to determine the elevation using accepted hydrologic/hydraulic practice (§ 1612A.3 and § 1612A.3.1) .

Which standard contains the numerical formulas for tsunami and flood loads?

The CBC directs you to ASCE 7 (Chapter 5 for flood‑related load provisions and Chapter 6 for tsunami loads) and to ASCE 24 for flood‑resistant design of components; the CBC itself defines applicability and references those standards (§ 1612A.2, § 1615A.1) .

Are temporary event tents and stages exempt from flood/tsunami design?

Temporary public‑occupancy structures that comply with the controlled‑occupancy temporary structure provisions of Section 3103.6 may be excepted from the flood and tsunami design requirements in §§ 1612 and 1615 when the conditions of § 3103.6 are met .

If my project is on the edge of a Tsunami Design Zone, who decides whether § 1615 applies?

The CBC allows the enforcement agency to use the ASCE Tsunami Design Geodatabase or other data determined applicable by the enforcement agency to establish Tsunami Design Zones; coordination with the local authority and the design professional is required (§ 1615A.1) .

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