CHBC · California Historical Building Code

How are parapets and nonstructural features evaluated for seismic hazard?

If you own a historic building in California, CHBC requires checking any parapet, cornice or decorative element that could fall in an earthquake. A qualified engineer must document the anchorage and either verify it resists seismic forces or strengthen it. The seismic demand can be taken from ASCE 41 or limited to 75% of the regular‑code forces; partitions and ceilings serving corridors/stairs with 30+ occupants also must be checked.

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Last reviewed: July 6, 2026

What the code requires — 2-4 sentences

The California Historical Building Code requires that parapets and exterior decoration be investigated for anchorage and their ability to resist the prescribed seismic forces (§ 8-706.4). Nonstructural features that could fall and create life-safety hazards (for example exterior veneer, cornices, decorations) must be evaluated and either verified for seismic resistance or strengthened/anchored as appropriate (§ 8-706.5). The seismic forces used for those evaluations must comply with ASCE 41 or need not exceed 0.75 times the seismic forces prescribed by the regular code (§ 8-706.5.2) .

Parapets and decorative elements that can fall and injure people must be investigated and anchored; use ASCE 41 or a seismic demand no greater than 0.75× the regular-code forces. § 8-706.4, § 8-706.5, § 8-706.5.2

Requirements in detail

What to check (high‑level)

  • Inspect the anchorage of parapets and exterior decorative elements and confirm their capacity to resist seismic forces (§ 8-706.4) .
  • Identify nonstructural features (exterior veneer, cornices, hanging decorations, masonry ornamentation) that could fall and create life‑safety hazards and evaluate their seismic performance; strengthen anchors where needed (§ 8-706.5) .
  • Special check for partitions and ceilings that serve corridors or stairways with an occupant load ≥ 30 — these must be investigated to determine ability to remain in place during earthquake forces (§ 8-706.5.1) .
  • Use seismic forces per ASCE 41 for nonstructural evaluation, or, alternatively, use forces that do not exceed 0.75 times the forces required by the regular code (§ 8-706.5.2) .

Decision‑relevant dimensions and values (quick reference)

Decision dimension Trigger / value to watch Required action Code reference
Parapet or exterior ornamentation present Any parapet / exterior decoration on a qualified historical building Investigate anchorage & ability to resist prescribed seismic forces; strengthen/anchor if hazardous § 8-706.4
Nonstructural feature that could fall (veneer, cornice, decoration) Any feature judged capable of falling and causing injury Evaluate seismic resistance; verify forces or provide improved anchorage § 8-706.5
Partitions / ceilings in egress paths Corridor or stairway serving occupant load ≥ 30 Investigate to confirm they remain in place under earthquake forces § 8-706.5.1
Force level to use for nonstructural evaluation Basis: ASCE 41 or not to exceed 0.75× regular-code seismic forces Use ASCE 41 procedures, or cap regular-code forces at 0.75 when evaluating/strengthening anchors § 8-706.5.2
Overarching evaluation approach Historic materials / detailing differ from regular code CHBC permits evaluating ultimate capacity, ductility and reserve strength; exercise broad judgment where appropriate § 8-706.2, § 8-706.1

Practical evaluation steps (recommended workflow)

  1. Document the feature (type, weight/size, attachment details, condition). Follow the CHBC-required structural survey process for historical structures (§ 8-703) .
  2. Identify life-safety risk: could the element fall onto a public way, egress path, or occupied space? If yes, it triggers strengthening/evaluation per § 8-706.5 .
  3. Select seismic demand basis: either apply ASCE 41 procedures, or compute the regular-code seismic demand and cap it at 0.75× that value per § 8-706.5.2 .
  4. Compare demand to existing anchorage capacity; if capacity < demand, design anchors or bracing to meet the chosen demand. Document and submit to enforcing agency.
  5. Where detail or materials are archaic, assign strength values rationally (tests if needed) and seek concurrence from the enforcing agency as described in Chapter 8‑8 and § 8-702–8-704 .

Exceptions & special cases

  • The CHBC explicitly allows an exception to regular-code anchorage requirements for parapets and decorations that are judged not to be a hazard to life safety; such elements may be treated differently after evaluation (§ 8-706.4) .
  • For nonstructural evaluation forces, you may choose ASCE 41 procedures as the seismic basis; alternatively, you may use regular-code forces reduced by 25% (i.e., 0.75×) instead of the full regular-code forces (§ 8-706.5.2) .
  • Where historical materials or detailing are nonconforming with regular code, CHBC permits using ultimate capacity, ductility and engineering judgment to determine acceptable performance levels; if a member would reasonably be expected to fail and cause collapse or life‑threatening injury it must be strengthened (§ 8-706.2.1) .
  • The CHBC requires a structural survey by a qualified architect or engineer for all evaluations; assigned allowable stresses for archaic materials should be justified and are subject to the enforcing agency’s concurrence (§ 8-703, Section 8‑802) .

Common mistakes

  • Assuming parapets are exempt from evaluation because the building is historic — CHBC still requires investigation for anchorage and seismic resistance unless the element is expressly judged not a life-safety hazard (§ 8-706.4) .
  • Using the full regular-code seismic forces automatically without checking the CHBC cap — for nonstructural features you must either use ASCE 41 or not exceed 0.75× the regular-code forces (§ 8-706.5.2) .
  • Forgetting to evaluate partitions/ceilings in corridors and stairs when occupant load is 30 or more — that is explicitly required (§ 8-706.5.1) .
  • Treating weight/mass as the only factor — anchorage details, stiffness, relative displacement and interaction with adjacent elements matter and must be considered in the evaluation (CHBC guidance on load path and survey: § 8-706.3, § 8-703) .
  • Failing to document the engineering basis for assigned strength values for archaic materials — CHBC expects tests or rational assignment and enforcing agency concurrence (Chapter 8‑8 and § 8-802) .

Worked example — concrete scenario with numbers

Scenario: A historic building has a decorative masonry cornice (a nonstructural feature) weighing 600 lb attached to the wall. The regular code seismic evaluation (ASCE 7 / local regular code) produces a required horizontal design seismic force of 400 lb acting on that element.

Step 1 — Choose basis under CHBC: Either (A) evaluate using ASCE 41 procedures, or (B) use regular-code force capped at 0.75×. The owner and engineer opt to use the CHBC cap for simplicity.

Step 2 — Apply CHBC cap per § 8-706.5.2: 0.75 × 400 lb = 300 lb. So the seismic demand used for anchorage design is 300 lb rather than the 400 lb from regular code .

Step 3 — Inspect existing anchorage: suppose existing anchors are rated at 200 lb (capacity). Since 200 lb < demand 300 lb, anchorage is inadequate per § 8-706.5 and must be strengthened or replaced .

Step 4 — Design new anchors to resist at least the 300‑lb seismic demand (select anchors with sufficient capacity, provide redundancy, and document installation). Submit evaluation and retrofit drawings to the enforcing agency as part of the CHBC review.

Notes: If instead the team uses ASCE 41 and that method yields a demand of 250 lb, the ASCE 41 result would govern (ASCE 41 compliance is explicitly permitted by § 8-706.5.2) .

Related provisions (CHBC)

  • § 8-706.4 — Parapets and exterior decoration; anchorage and seismic resistance required
  • § 8-706.5 — Nonstructural features that could fall; evaluate and strengthen as appropriate
  • § 8-706.5.1 — Partitions and ceilings in corridors/stairways with occupant load 30 or more must be investigated
  • § 8-706.5.2 — Seismic forces for nonstructural evaluation: ASCE 41 or ≤ 0.75× regular-code forces
  • § 8-706.1 / § 8-706.2 — General seismic force basis and permitted use of ultimate-capacity / reserve strength approaches for historical structures
  • § 8-703 — Structural survey requirements for historical structures (data collection and documentation)

Code references

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

  • CHBC § 8-706.1.3 High relevance — show source text

    Exceptions:

    1. Alternative standards may be used on a case-by-case basis when approved by the authority having jurisdiction. It shall be permitted to exceed the strength limitation of 100 psi in Section A108.2 of the CEBC when test data and building configuration supports higher values subject to the approval of the authority having jurisdiction.
    2. CEBC Section A102.2 shall not apply to Qualified Historical Buildings in Risk Category III buildings and other structures whose primary occupancies are public assembly with an occupancy load greater than 300.

    8-706.1.3 All deviations from the detailing provisions of the lateral-force-resisting systems shall be evaluated for stability and the ability to maintain load-carrying capacity at the expected inelastic deformations.

    8-706.2 Existing building performance. The seismic resistance may be based upon the ultimate capacity of the structure to perform, giving due consideration to ductility and reserve strength of the lateral-force-resisting system and materials while maintaining a reasonable factor of safety. Broad judgment may be exercised regarding the strength and performance of materials not recognized by regular code requirements. (See Chapter 8-8, Archaic Materials and Methods of Construction.)

    8-706.2.1 All structural materials or members that do not comply with detailing and proportioning requirements of the regular code shall be evaluated for potential seismic performance and the consequence of non-compliance. All members that would be reasonably expected to fail and lead to collapse or life threatening injury when subjected to seismic demands shall be judged unacceptable, and appropriate structural strengthening shall be developed.

    8-706.3 Load path. A complete and continuous load path, including connections, from every part or portion of the structure to the ground shall be provided for the required forces. It shall be verified that the structure is adequately tied together to perform as a unit when subjected to earthquake forces.

    8-706.4 Parapets. Parapets and exterior decoration shall be investigated for conformance with regular code requirements for anchorage and ability to resist prescribed seismic forces.

    An exception to regular code requirements shall be permitted for those parapets and decorations which are judged not to be a hazard to life safety.

    8-706.5 Nonstructural features. Nonstructural features of historical structure, such as exterior veneer, cornices and decorations, which might fall and create a life safety hazard in an earthquake, shall be evaluated. Their ability to resist seismic forces shall be verified, or the feature shall be strengthened with improved anchorage when appropriate.

    8-706.5.1 Partitions and ceilings of corridors and stairways serving an occupant load of 30 or more shall be investigated to determine their ability to remain in place when the building is subjected to earthquake forces.

    8-706.5.2 Seismic forces used to evaluate and improve nonstructural components and their anchorage, where required, shall comply with ASCE 41 or need not exceed 0.75 times the seismic forces prescribed by the requirements of the regular code.

    14 2025 CALIFORNIA HISTORICAL BUILDING CODE

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

    8-8 ARCHAIC MATERIALS AND METHODS OF CONSTRUCTION

    SECTION 8-801 — PURPOSE, INTENT AND SCOPE

  • CHBC § 8-706.3 High relevance — show source text

    8-706.3 Load path. A complete and continuous load path, including connections, from every part or portion of the structure to the ground shall be provided for the required forces. It shall be verified that the structure is adequately tied together to perform as a unit when subjected to earthquake forces.

    8-706.4 Parapets. Parapets and exterior decoration shall be investigated for conformance with regular code requirements for anchorage and ability to resist prescribed seismic forces.

    An exception to regular code requirements shall be permitted for those parapets and decorations which are judged not to be a hazard to life safety.

    8-706.5 Nonstructural features. Nonstructural features of historical structure, such as exterior veneer, cornices and decorations, which might fall and create a life safety hazard in an earthquake, shall be evaluated. Their ability to resist seismic forces shall be verified, or the feature shall be strengthened with improved anchorage when appropriate.

    8-706.5.1 Partitions and ceilings of corridors and stairways serving an occupant load of 30 or more shall be investigated to determine their ability to remain in place when the building is subjected to earthquake forces.

    8-706.5.2 Seismic forces used to evaluate and improve nonstructural components and their anchorage, where required, shall comply with ASCE 41 or need not exceed 0.75 times the seismic forces prescribed by the requirements of the regular code.

    14 2025 CALIFORNIA HISTORICAL BUILDING CODE

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

    8-8 ARCHAIC MATERIALS AND METHODS OF CONSTRUCTION

    SECTION 8-801 — PURPOSE, INTENT AND SCOPE

    8-801.1 Purpose. The purpose of the CHBC is to provide regulations for the use of historical methods and materials of construction that are at variance with regular code requirements or are not otherwise codified, in buildings or structures designated as qualified historical buildings or properties. The CHBC require enforcing agencies to accept any reasonably equivalent alternatives to the regular code when dealing with qualified historical buildings or properties.

    8-801.2 Intent. It is the intent of the CHBC to provide for the use of historical methods and materials of construction that are at variance with specific code requirements or are not otherwise codified.

    8-801.3 Scope. Any construction type or material that is, or was, part of the historical fabric of a structure is covered by this chapter. Archaic materials and methods of construction present in a historical structure may remain or be reinstalled or be installed with new materials of the same class to match existing conditions.

    SECTION 8-802 — GENERAL ENGINEERING APPROACHES

    Strength values for archaic materials shall be assigned based upon similar conventional codified materials, or on tests as hereinafter indicated. The archaic materials and methods of construction shall be thoroughly investigated for their details of construction in accordance with Section 8-703. Testing shall be performed when applicable to evaluate existing conditions. The architect or structural engineer in responsible charge of the project shall assign allowable stresses or strength levels to archaic materials. Such assigned strength values shall not be greater than those provided for in the following sections without adequate testing, and shall be subject to the concurrence of the enforcing agency.

    SECTION 8-803 — NONSTRUCTURAL ARCHAIC MATERIALS

  • CHBC § 3104F.5 High relevance — show source text

    3104F.5 Nonstructural components, nonbuilding structures and building structures. Nonstructural components, nonbuilding struc- tures and building structures at MOTs shall be assessed for Level 2 seismic performance (see Section 3104F.2.1). Consideration shall be given to the adequacy and condition of supports and attachments (or anchorage), strength, flexibility, relative displacement, P-delta effects, and seismically-induced interaction with other components and structures.

    3104F.5.1 General. Nonstructural components are mechanical, electrical and architectural components (such as piping/pipelines, loading arms, lifting equipment (winches and cranes), spill prevention equipment, pumps, instrumentation and storage cabinets, and lighting fixtures) that may be required to resist the effects of earthquake.

    Nonbuilding structures (such as gangways, hose towers and racks) are self-supporting structures that carry gravity loads and may be required to resist the effects of earthquake, but are not building structures (such as control rooms). For building structures, see Section 3104F.5.6.

    Critical systems are nonstructural components, nonbuilding structures or building structures that shall remain operational or those whose failure could impair emergency operations following an earthquake, to prevent major oil spills and to protect public health, safety and the environment. A seismic assessment of the survivability and continued operation (related to personnel safety, oil spill prevention or response) during a Level 2 earthquake (see Table 31F-4-1) shall be performed for critical systems, including but not limited to, fire protection, emergency shutdown and electrical power systems.

    3104F.5.2 Seismic assessment. For existing (E) nonstructural components, nonbuilding structures and building structures and their supports and attachments, seismic assessment shall be performed in accordance with CalARP [4.8] or ASCE Guidelines [4.9], except for piping/pipelines which shall be evaluated per Section 3109F. If seismic evaluation and/or strengthening are required, it shall be performed in accordance with Section 3104F.5.2.1.

    For new (N) nonstructural components, nonbuilding structures and building structures and their supports and attachments, seis- mic evaluation and design shall be performed in accordance with Section 3104F.5.2.1, except for piping/pipelines which shall be evaluated per Section 3109F.

    3104F.5.2.1 Seismic evaluation, strengthening and design. For evaluation, strengthening and design of nonstructural compo- nents, nonbuilding structures and building structures, seismic forces (demands) shall be obtained from Section 3104F.5. The seismic adequacy of nonstructural components shall be demonstrated as specified in ASCE/SEI 7 [4.1]. Structures shall be analyzed in accordance with Section 3107F.5. Supports and attachments shall be assessed in accordance with Sections 3107F.7.

    3104F.5.3 Contribution to global response of MOT structures. Nonstructural components, nonbuilding structures and building structures permanently attached to MOT structures, including, but not limited to, pipelines, loading arms, hose towers/racks, raised platforms, control rooms and vapor control equipment, may affect the global structural response. In such cases, the seismic charac- teristics (mass and/or stiffness) of the nonstructural components, nonbuilding structures and building structures shall be considered _in computing global seismic response of the MOT structures.

  • CHBC § 503.7 High relevance — show source text

    [BS] 503.7 Anchorage for concrete and reinforced masonry walls. Where the work area exceeds 50 percent of the building area, the building is assigned to Seismic Design Category C, D, E or F and the building’s structural system includes concrete or reinforced masonry walls with a flexible roof diaphragm, the alteration shall comply with Section 304.3.2 by evaluation of the existing condition or by installation of wall anchors at the roof line.

    [BS] 503.8 Anchorage for unreinforced masonry walls in major alterations. Where the work area exceeds 50 percent of the building area, the building is assigned to Seismic Design Category C, D, E or F and the building’s structural system includes unreinforced masonry bearing walls, the alteration shall comply with Section 304.3.2 by evaluation of the existing condition or by installation of wall anchors at the floor and roof lines.

    [BS] 503.9 Bracing for unreinforced masonry parapets in major alterations. Where the work area exceeds 50 percent of the building area, and where the building is assigned to Seismic Design Category C, D, E or F, and the building has parapets constructed of unreinforced masonry, the alteration shall comply with Section 304.3.2 by evaluation of the existing condition or by installation of parapet bracing to resist out-of-plane seismic forces.

    [BS] 503.10 Anchorage of unreinforced masonry partitions in major alterations. Where the work area exceeds 50 percent of the building area, or where the building is assigned to Seismic Design Category C, D, E or F, and the building has unreinforced masonry partitions and nonstructural walls, the alteration work shall include evaluation of the existing condition or removal, anchoring or alteration of any such partitions or walls within the work area and adjacent to egress paths from the work area, to comply with Section 304.3.2.

    [BS] 503.11 Substantial structural alteration. Where the work area exceeds 50 percent of the building area and where work involves a substantial structural alteration, the lateral load-resisting system of the altered building shall satisfy the requirements of Section 1609 of the California Building Code and Section 304.3.2 of this code. Where the building is assigned to Seismic Design Category D or F, supports and attachments for nonstructural components required to serve any portion of the building with a use included in Risk Category IV shall comply with Section 1613 of the California Building Code or shall comply with ASCE 41 using an objective of Position Retention nonstructural performance with the BSE-1E earthquake hazard level.

    Exceptions:

    1. Buildings of Group R occupancy with not more than five dwelling or sleeping units used solely for residential purposes that are altered based on the conventional light-frame construction methods of the California Building Code or in compliance with the provisions of the California Residential Code .
    2. Where the intended alteration involves structural components of the lowest story of a building, only the lateral loadresisting system above that story need not comply with this section.

    [BS] 503.12 Roof diaphragms resisting wind loads in high-wind regions. Where the intended alteration requires a permit for reroofing and involves removal of roofing materials from more than 50 percent of the roof diaphragm of a building or section of a building located where the basic wind speed, V, is greater than 130 mph (58 m/s) in accordance with Figure 1609.3(2) of the California

  • CHBC § 906.2 High relevance — show source text

    [BS] 906.2 Existing structural elements resisting lateral loads. Where work involves a substantial structural alteration,the lateral load-resisting system of the altered building shall be shown to satisfy the requirements of Section 1609 of the California Building Code and Section 304.3.2 of this code. Where the building is assigned to Seismic Design Category D or F, supports and attachments for nonstructural components required to serve any portion of the building with a use included in Risk Category IV shall comply with Section 1613 of the California Building Code or shall comply with ASCE 41 using an objective of Position Retention nonstructural performance with the BSE-1E earthquake hazard level.

    Exceptions:

    1. Buildings of Group R occupancy with not more than five dwelling or sleeping units used solely for residential purposes that are altered based on the conventional light-frame construction methods of the California Building Code or in compliance with the provisions of the California Residential Code .
    2. Where the intended alteration involves only the lowest story of a building, structural components of the lateral load resisting system above that story need not comply with this section.

    [BS] 906.3 Seismic Design Category F. Where the building is assigned to Seismic Design Category F, the lateral force-resisting system of the altered building shall meet the requirements of Section 1609 of the California Building Code and Section 304.3.2 of this code. Supports and attachments for nonstructural components serving any portion of the building with a use included in Risk Cate- gory IV shall comply with Section 1613 of the California Building Code or shall comply with ASCE 41 using an objective of Position Retention nonstructural performance with the BSE-1E earthquake hazard level.

    [BS] 906.4 Anchorage for concrete and masonry buildings. For any building assigned to Seismic Design Category D, E or F with a structural system that includes concrete or reinforced masonry walls with a flexible roof diaphragm, the alteration shall comply with Section 304.3.2 by evaluation of the existing condition or by installation of wall anchors at the roof line of all subject buildings and at the floor lines of unreinforced masonry.

    [BS] 906.5 Anchorage for unreinforced masonry walls. For any building assigned to Seismic Design Category C, D, E or F with a structural system that includes unreinforced masonry bearing walls, the alteration shall comply with Section 304.3.2 by evaluation of the existing condition or by installation of wall anchors at the roof line.

    [BS] 906.6 Bracing for unreinforced masonry parapets. Parapets constructed of unreinforced masonry in buildings assigned to Seismic Design Category C, D, E or F shall comply with Section 304.3.2 by evaluation of the existing condition or by installation of parapet bracing.

    [BS] 906.7 Anchorage of unreinforced masonry partitions. Where the building is assigned to Seismic Design Category C, D, E or F, unreinforced masonry partitions and nonstructural walls within the work area and adjacent to egress paths from the work area shall have their existing conditions evaluated or shall be anchored, removed or altered to resist out-of-plane seismic forces to comply with Section 304.3.2.

    SECTION 907—ENERGY CONSERVATION

    907.1 Minimum requirements. Level 3 alterations to existing buildings or structures shall comply with applicable provisions of the California Energy Code (Part 6, Title 24, C.C.R).

  • CHBC § 181.4 High relevance — show source text
    1. Buildings in which the increase in the demand-capacity ratio is due entirely to the addition of rooftop-supported mechanical equipment individually having an operating weight less than 400 pounds (181.4 kg) and where the total additional weight of all rooftop equipment placed after initial construction of the building is less than 10 percent of the roof dead load. For purposes of this exception, “roof” shall mean the roof level above a particular story.
    2. Increases in the demand-capacity ratio due to lateral loads from seismic forces need not be evaluated for the installation of rooftop photovoltaic panel systems where the additional roof dead load due to the system, including ballast where applicable, does not exceed 5 pounds per square foot (psf) (0.2394 kN/m [2] ) and does not exceed 10 percent of the dead load of the existing roof.

    [BS] 503.5 Seismic Design Category F. Where the work area exceeds 50 percent of the building area, and where the building is assigned to Seismic Design Category F, the lateral force-resisting system of the altered building shall meet the requirements of Section 1609 of the California Building Code and Section 304.3.2 of this code. Supports and attachments for nonstructural components serving any portion of the building with a use included in Risk Category IV shall comply with Section 1613 of the California Building Code or shall comply with ASCE 41 using an objective of Position Retention nonstructural performance with the BSE-1E earthquake hazard level.

    [BS] 503.6 Bracing for unreinforced masonry parapets on reroofing. Where the intended alteration requires a permit for reroofing and involves removal of roofing materials from more than 25 percent of the roof area of a building assigned to Seismic Design Category D, E or F that has parapets constructed of unreinforced masonry, the work shall comply with Section 304.3.2 by evaluation of the existing condition or by installation of parapet bracing to resist out-of-plane seismic forces.

    [BS] 503.7 Anchorage for concrete and reinforced masonry walls. Where the work area exceeds 50 percent of the building area, the building is assigned to Seismic Design Category C, D, E or F and the building’s structural system includes concrete or reinforced masonry walls with a flexible roof diaphragm, the alteration shall comply with Section 304.3.2 by evaluation of the existing condition or by installation of wall anchors at the roof line.

    [BS] 503.8 Anchorage for unreinforced masonry walls in major alterations. Where the work area exceeds 50 percent of the building area, the building is assigned to Seismic Design Category C, D, E or F and the building’s structural system includes unreinforced masonry bearing walls, the alteration shall comply with Section 304.3.2 by evaluation of the existing condition or by installation of wall anchors at the floor and roof lines.

    [BS] 503.9 Bracing for unreinforced masonry parapets in major alterations. Where the work area exceeds 50 percent of the building area, and where the building is assigned to Seismic Design Category C, D, E or F, and the building has parapets constructed of unreinforced masonry, the alteration shall comply with Section 304.3.2 by evaluation of the existing condition or by installation of parapet bracing to resist out-of-plane seismic forces.

  • CHBC § 3104F.5.4.1.2 High relevance — show source text

    0_
    3.5
    8.0
    4.5
    3.5
    6.5
    6.5
    2.0| |Other|Subject to Division approval| |1. A higher value may be utilized, subject to Division approval.|1. A higher value may be utilized, subject to Division approval.|

    3104F.5.4.1.2 Linear modal demand procedure. The linear modal demand procedure (Section 3104F.2.3.3) may always be used and shall be used to estimate seismic forces when the Simplified Procedure (Section 3104F.5.4.1.1) is not permitted. The MOT structure and nonstructural components and/or nonbuilding structures shall be modeled explicitly. The seismic forces obtained from the linear modal demand procedure shall be adjusted for appropriate importance factors and response modifi- cation factors as specified in Table 31F-4-4 and Table 31F-4-5.

    3104F.5.5 Nonstructural components and nonbuilding structures permanently attached to the ground. The seismic load shall be computed using the procedures in ASCE/SEI 7 [4.1], except that Level 2 design earthquake motion parameters defined in Section 3103F.4 shall be used in lieu of those specified in ASCE/SEI 7 [4.1].

    3104F.5.6 Building structures. For buildings permanently attached to MOT structure, Section 3104F.5.4.1 shall be used to compute seismic loads. Computation of seismic effects shall consider: 1. Amplification of acceleration from ground to location of attachment of the building to the deck due to flexibility of the MOT structure, and

    2. Amplification of acceleration due to flexibility of the building.

    For buildings permanently attached to the ground, seismic loads shall be computed using the procedures in ASCE/SEI 7 [4.1], as amended by the local enforcing agency requirements, subject to Division approval.

    3104F.6 Symbols.

    a = Site class factor

    a p = Amplification factor for nonstructural component or nonbuilding structure A x = Torsional amplification factor

    C 1 = Modification factor to relate expected maximum inelastic displacement to displacement calculated for linear elastic response

    C 2 = Modification factor to represent the effects of pinched hysteresis shape, cyclic stiffness degradation and strength deterioration on the maximum displacement response

    e = Eccentricity between center of mass and center of rigidity F d, i = Force at step i of iteration F d, j = Force at step j of iteration F p = Horizontal seismic force on nonstructural component, nonbuilding structure or building structure supported on MOT F v = Vertical seismic force on nonstructural component, nonbuilding structure or building structure supported on MOT F y = Effective yield strength H = Distance from maximum in-ground moment to center of gravity of the deck I p = Importance factor for nonstructural component or nonbuilding structure k e = Effective elastic lateral stiffness k eff, i = Effective secant lateral stiffness at step i of iteration k _eff,

  • CHBC § 501A.3.3 High relevance — show source text

    Elements not part of the Seismic Force-Resisting System (SFRS), including those identified in the California Administrative Code Chapter 6, Article 10, shall be evaluated using seismic forces and the requirements of this code for new general acute care hospital buildings.

    501A.3.3 Prescriptive compliance provisions for NPC 2, NPC 3, NPC 4 or NPC 4D and NPC 5.

    501A.3.3.1 Supports and attachments of nonstructural components, except those listed in Section 501A.3.3.2 below, in buildings in seismic performance categories SPC 1 or SPC 2 with a performance level of NPC 3 or higher, and SPC 3, SPC 4 or SPC-4D, shall be permitted to comply with the provisions of Section 1630B of the 1998 California Building Code using an importance factor I p =1.5. The capacity of welds, anchors and fasteners shall be determined in accordance with requirements of the California Building Code for new construction.

    501A.3.3.2 Supports and attachments for systems listed under NPC-2 and NPC-5 (excluding those specifically listed for NPC-3 and NPC-4 or NPC-4D) in the California Administrative Code, Chapter 6, Table 11.1 shall satisfy the requirements of the California Build- ing Code for new construction and Section 501A.3.3.1 above shall not be applicable.

    501A.3.3.3 For NPC 3 and NPC 4 or NPC 4D in SPC 2, SPC 3, SPC 4 or SPC-4D buildings, the adequacy and design of nonstructural component or equipment supports and attachments may extend only to the connection of the component or equipment to the support when the total reaction at the point of support (including the application of F p ) is less than or equal to the following limits: 1. 250 pounds for components or equipment attached to light frame walls. For the purposes of this requirement, the sum of the absolute value of all reactions due to component loads on a single stud shall not exceed 250 pounds. 2. 1,000 pounds for components or equipment attached to roofs or walls of reinforced concrete or masonry construction. 3. 2,000 pounds for components or equipment attached to floors or slabs-on-grade.

    Exception: If the anchorage or bracing is configured in a manner that results in significant torsion on a supporting structural element, the effects of the nonstructural reaction force on the structural element shall be considered in the anchorage design.

    501 A . 4 Health care facilities. In Group I-2 facilities, ambulatory care facilities and outpatient clinics, any altered or added portion of an existing electrical or medical gas systems shall be required to meet installation and equipment requirements in NFPA 99.

    SECTION 502 A —ADDITIONS

  • CHBC § 8-706 High relevance — show source text

    SECTION 8-706 — LATERAL LOAD REGULATIONS

    8-706.1 Seismic forces. Strength-level seismic forces used to evaluate the structure for resistance to seismic loads shall be based on the R -values tabulated in the regular code for similar lateral-force-resisting systems including consideration of the structural detailing of the members where such R -values exist. Where such R -values do not exist, an appropriate R -value shall be rationally assigned considering the structural detailing of the members.

    Exceptions:

    1. The forces need not exceed 0.75 times the seismic forces prescribed by the regular code requirements.
    2. For Risk Category I, II or III structures, near-fault increases in ground motion (maximum considered earthquake ground motion of 0.2 second spectral response greater than 150 percent at 5 percent damping) need not be considered when the fundamental period of the building is 0.5 seconds in the direction under consideration.
    3. For Risk Category I or II structures, the seismic base shear need not exceed 0.30W.
    4. For Risk Category III or IV structures, the seismic base shear need not exceed 0.40W.

    8-706.1.1 When a building is to be strengthened with the addition of a new lateral force resisting system, the R -value of the new system can be used when the new lateral force resisting system resists at least 75 percent of the building’s base shear regardless of its relative rigidity.

    8-706.1.2 Evaluation and seismic improvement of unreinforced masonry bearing wall buildings shall comply with the California Existing Building Code (CEBC), Appendix Chapter A1 2013 Edition, and as modified by the CHBC.

    Exceptions:

    1. Alternative standards may be used on a case-by-case basis when approved by the authority having jurisdiction. It shall be permitted to exceed the strength limitation of 100 psi in Section A108.2 of the CEBC when test data and building configuration supports higher values subject to the approval of the authority having jurisdiction.
    2. CEBC Section A102.2 shall not apply to Qualified Historical Buildings in Risk Category III buildings and other structures whose primary occupancies are public assembly with an occupancy load greater than 300.

    8-706.1.3 All deviations from the detailing provisions of the lateral-force-resisting systems shall be evaluated for stability and the ability to maintain load-carrying capacity at the expected inelastic deformations.

    8-706.2 Existing building performance. The seismic resistance may be based upon the ultimate capacity of the structure to perform, giving due consideration to ductility and reserve strength of the lateral-force-resisting system and materials while maintaining a reasonable factor of safety. Broad judgment may be exercised regarding the strength and performance of materials not recognized by regular code requirements. (See Chapter 8-8, Archaic Materials and Methods of Construction.)

    8-706.2.1 All structural materials or members that do not comply with detailing and proportioning requirements of the regular code shall be evaluated for potential seismic performance and the consequence of non-compliance. All members that would be reasonably expected to fail and lead to collapse or life threatening injury when subjected to seismic demands shall be judged unacceptable, and appropriate structural strengthening shall be developed.

    8-706.3 Load path. A complete and continuous load path, including connections, from every part or portion of the structure to the ground shall be provided for the required forces. It shall be verified that the structure is adequately tied together to perform as a unit when subjected to earthquake forces.

  • CHBC § 31F-45 High relevance — show source text

    m = Seismic mass

    R p = Response modification factor for nonstructural component or nonbuilding structure S A = Spectral response acceleration at T

    2025 CALIFORNIA BUILDING CODE 31F-45

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

    MARINE OIL TERMINALS

    S xs = Spectral acceleration in Section 3103F.4.2.4 or Section 3103F.4.2.5

    S 1 = 1-second spectral response acceleration

    T = Fundamental period of the elastic structure

    T e = Effective elastic structural period T eff, i = Effective structural period at step i of iteration T p = Period of flexible nonstructural component or nonbuilding structure T 0 = Period at peak of the acceleration response spectrum

    V = Base shear strength of the structure obtained from a plastic analysis

    V sk = Shear force across shear keys

    V Δ T = Total segment lateral force

    W = Dead load of the frame

    W p = Weight of the nonstructural component or nonbuilding structure Δ d = Target displacement demand Δ d, i = Target displacement demand at step i of iteration Δ d, j = Target displacement demand at step j of iteration α 1 = Positive post-yield slope ratio equal to positive post-yield stiffness divided by the effective stiffness

    α 2 = Negative post-yield slope ratio equal to negative post-yield stiffness divided by the effective stiffness

    α e = Effective negative post-yield slope ratio equal to effective post-yield negative stiffness divided by the effective stiffness

    α P- Δ = Negative slope ratio caused by P- Δ effects Δ avg = Average of displacements, Δ 1 and Δ 2 , at ends of the MOT transverse to an axis Δ d = Target displacement

    Δ m = Maximum of displacements, Δ 1 and Δ 2 , at ends of the MOT transverse to an axis Δ y = Displacement at yield strength Δ 1 , Δ 2 = Displacement at ends of the MOT transverse to an axis δ d = Design displacement demand at an element δ x = Displacement of an element in X direction δ y = Displacement of an element in Y direction δ xx = X displacement under X direction excitation δ xy = X displacement under Y direction excitation δ yx = Y displacement under X direction excitation δ yy = Y displacement under Y direction excitation λ = Near-field effect factor

    μ max = Maximum strength ratio μ strength = Ratio of elastic strength demand to yield strength μ Δ,ι = Initial ductility level ξ eff,i = Effective structural damping at step i of iteration

    3104F.7 References.

    [4.1] American Society of Civil Engineers (ASCE), 2016, ASCE/SEI 7-16 (ASCE/SEI 7), “Minimum Design Loads and Associates Criteria for Buildings and Other Structures,” Reston, VA.

  • CHBC § 319.1 Medium relevance — show source text

    When evaluating for the Hazards Reduced Nonstructural Performance Level, the requirements need not be greater than what would be_
    required by ASCE 7 nonstructural provisions for new construction.
    2. Buildings evaluated and retrofitted to meet the structural and nonstructural requirements for a new building as given in the California Building Code as adopted by DSA or BSC, as
    applicable, are deemed to meet the seismic performance requirements of this section.
    3. Buildings complying with the requirements of the exception in Section 319.1 are deemed to meet the seismic performance requirements of this section.
    4. State-owned and state-leased essential services buildings are subject to the regulatory authority of DSA-SS per Section 1.9.2.1.|1. ASCE 41 provides acceptance criteria (e.g., m-factor, rotation) for Immediate Occupancy (S1), Life Safety (S3) and Collapse Prevention (S5), and specifies in Table 2-1 the method
    to interpolate values for S-2 and S-4. When evaluating for the Hazards Reduced Nonstructural Performance Level, the requirements need not be greater than what would be
    required by ASCE 7 nonstructural provisions for new construction.
    2. Buildings evaluated and retrofitted to meet the structural and nonstructural requirements for a new building as given in the California Building Code as adopted by DSA or BSC, as
    applicable, are deemed to meet the seismic performance requirements of this section.
    3. Buildings complying with the requirements of the exception in Section 319.1 are deemed to meet the seismic performance requirements of this section.
    4. State-owned and state-leased essential services buildings are subject to the regulatory authority of DSA-SS per Section 1.9.2.1.|1. ASCE 41 provides acceptance criteria (e.g., m-factor, rotation) for Immediate Occupancy (S1), Life Safety (S3) and Collapse Prevention (S5), and specifies in Table 2-1 the method
    to interpolate values for S-2 and S-4. When evaluating for the Hazards Reduced Nonstructural Performance Level, the requirements need not be greater than what would be
    required by ASCE 7 nonstructural provisions for new construction.
    2. Buildings evaluated and retrofitted to meet the structural and nonstructural requirements for a new building as given in the California Building Code as adopted by DSA or BSC, as
    applicable, are deemed to meet the seismic performance requirements of this section.
    3. Buildings complying with the requirements of the exception in Section 319.1 are deemed to meet the seismic performance requirements of this section.
    4. State-owned and state-leased essential services buildings are subject to the regulatory authority of DSA-SS per Section 1.9.2.1.|1. ASCE 41 provides acceptance criteria (e.g., m-factor, rotation) for Immediate Occupancy (S1), Life Safety (S3) and Collapse Prevention (S5), and specifies in Table 2-1 the method
    to interpolate values for S-2 and S-4. When evaluating for the Hazards Reduced Nonstructural Performance Level, the requirements need not be greater than what would be
    required by ASCE 7 nonstructural provisions for new construction.
    _2.

  • CHBC § 5-5 Medium relevance — show source text

    Exceptions:

    1. Any existing lateral load-carrying structural element whose demand-capacity ratio with the alteration considered is not more than 10 percent greater than its demand-capacity ratio with the alteration ignored shall be permitted to remain

    2025 CALIFORNIA EXISTING BUILDING CODE 5-5

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

    PRESCRIPTIVE COMPLIANCE METHOD

    unaltered. For purposes of calculating demand-capacity ratios, the demand shall consider applicable load combinations with design lateral loads or forces in accordance with Section 1609 of the California Building Code and Section 304.3.1 or 304.3.2 of this code. The same methodology shall be used for the altered and unaltered structures. 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 demandcapacity 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 of the California Building Code or the code wind forces in effect at the time. When calculating demand-capacity ratios for earthquake, 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 304.3.1 or Section 304.3.2, Item 1 or 3, or the full or reduced seismic forces in effect at the time.

    1. Buildings in which the increase in the demand-capacity ratio is due entirely to the addition of rooftop-supported mechanical equipment individually having an operating weight less than 400 pounds (181.4 kg) and where the total additional weight of all rooftop equipment placed after initial construction of the building is less than 10 percent of the roof dead load. For purposes of this exception, “roof” shall mean the roof level above a particular story.
    2. Increases in the demand-capacity ratio due to lateral loads from seismic forces need not be evaluated for the installation of rooftop photovoltaic panel systems where the additional roof dead load due to the system, including ballast where applicable, does not exceed 5 pounds per square foot (psf) (0.2394 kN/m [2] ) and does not exceed 10 percent of the dead load of the existing roof.

    [BS] 503.5 Seismic Design Category F. Where the work area exceeds 50 percent of the building area, and where the building is assigned to Seismic Design Category F, the lateral force-resisting system of the altered building shall meet the requirements of Section 1609 of the California Building Code and Section 304.3.2 of this code. Supports and attachments for nonstructural components serving any portion of the building with a use included in Risk Category IV shall comply with Section 1613 of the California Building Code or shall comply with ASCE 41 using an objective of Position Retention nonstructural performance with the BSE-1E earthquake hazard level.

Frequently asked questions

Who decides whether a parapet or decoration is “not a hazard to life safety” and therefore excepted from regular-code anchorage?

The authority having jurisdiction (building official) acts on the evaluation prepared by the design professional; § 8-706.4 allows an exception only for elements judged not to be a life‑safety hazard, so document the rationale and submit it for approval .

Can I always use the 0.75 multiplier instead of ASCE 41?

Yes — for the seismic forces used to evaluate nonstructural components the CHBC permits either compliance with ASCE 41 or use of forces that do not exceed 0.75× the regular-code forces (§ 8-706.5.2) .

Are partitions and ceilings in small corridors exempt from evaluation?

Not if they serve corridors or stairways with an occupant load of 30 or more — those must be investigated for ability to remain in place under earthquake forces per § 8-706.5.1 .

What if the material is “archaic” and no code strength values exist?

CHBC allows assigning strength values based on similar codified materials or testing; the engineer must document the basis and the enforcing agency must concur (see Chapter 8‑8 and § 8-802) .

Must the entire building be upgraded to regular-code levels because of parapet work?

No. CHBC permits targeted evaluation and strengthening of hazardous nonstructural items; the code emphasizes a reasonable, historically‑sensitive approach using engineering judgment and the limits noted in § 8-706 (for example the 0.75 force cap) .

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