CHBC · California Historical Building Code
When may natural cement, rubble or low‑strength concrete remain or be used?
If your building has historic natural‑cement, rubble, or low‑strength concrete, the CHBC allows it to stay only after a registered architect or engineer tests and documents its strength, determines bond/development requirements, and evaluates detailing and ductility; if these show unacceptable risk, the element must be strengthened or replaced (see § 8-808.1 and § 8-808.2) .
Last reviewed: July 6, 2026
What the code requires — plain English
- Natural cement concrete, unreinforced rubble concrete, and similar historical concretes may be retained or reinstalled where they were used historically, and existing concrete of low strength or with less reinforcement than the regular code calls for may remain in place — provided a design professional evaluates and assigns strengths and detailing is reviewed (§ 8-808.1, § 8-808.2) .
- The architect or engineer in responsible charge must assign allowable strength values based on testing or historical data, and must determine bond and development lengths from tests or historic practice (§ 8-808.1) .
- The design professional must also evaluate detailing deviations from the regular code, with attention to ductility and reserve strength and the structure’s ultimate performance (§ 8-808.2) .
The most important rule: if historical concrete materials are present, a qualified architect or structural engineer must test or document them, assign appropriate strength values, and evaluate detailing so the element’s performance (including ductility and reserve strength) is understood and acceptable (§ 8-808.1, § 8-808.2) .
Requirements in detail
What materials and conditions are allowed
- Natural cement concrete and unreinforced rubble concrete may be used or remain where they are part of the historical fabric (§ 8-808.1) .
- Concrete of low strength or concrete with less reinforcement than required by the regular code may remain in place if properly evaluated (§ 8-808.1) .
Who must evaluate and what they must do
- The architect or engineer must:
- Assign appropriate strength values based on sampling and testing of the existing material, or on comparable historic information (§ 8-808.1) .
- Determine bond and development lengths from historical information or tests (§ 8-808.1) .
- Carefully evaluate detailing provisions of the regular code that are not met and consider the implications for ultimate performance, ductility, and reserve strength (§ 8-808.2) .
How this fits into the CHBC engineering approach
- Strength values for archaic materials are to be assigned based on comparable codified materials or on tests; assigned values should not exceed limits in later sections without adequate testing, and are subject to the enforcing agency’s concurrence (§ 8-802) .
- A full structural survey and testing program is expected per the CHBC procedures referenced elsewhere (see § 8-703 and § 8-802) .
Decision-relevant table
| Decision factor | What to check / measure | Typical required action | Code reference |
|---|---|---|---|
| Material identity | Is the element natural cement, rubble concrete, or other historic concrete? | Permit it to remain or be reinstalled if historically appropriate; document condition | § 8-808.1 |
| Strength level | Measure compressive strength and inspect reinforcement | Architect/engineer assigns allowable strength based on tests; if inadequate, design strengthening | § 8-808.1 |
| Reinforcement detailing | Is reinforcement less than regular code or bond/development insufficient? | Determine bond/development lengths from tests or historic practice; design supplements if needed | § 8-808.1 |
| Code detailing deviations | What regular-code detailing is not met (e.g., confinement, lap splices)? | Evaluate implications for ductility and reserve strength; strengthen where required for safety | § 8-808.2 |
| Limits on assigned values | Were strength values assigned based on tests or analogous codified values? | Ensure assigned values are justified by tests or historic comparisons; enforcing agency concurrence as needed | § 8-802 |
Exceptions & special cases
- The CHBC does not give blanket numerical minimums or specific compressive-strength thresholds for “low strength” concrete in § 8-808.1; instead, the requirement is procedural: the design professional must assign values based on testing or historical information (§ 8-808.1) . If you need numeric limits or acceptance criteria, those must come from tests and engineering judgment or other referenced standards — the CHBC text does not provide them.
- Assigned strength values must be conservative and are subject to the enforcing agency’s concurrence; assigned values should not exceed those in other CHBC sections unless adequate testing supports higher values (§ 8-802) .
- If a member’s detailing or condition is such that failure would likely cause collapse or life‑threatening injury, that member is unacceptable and must be strengthened (see CHBC provisions on evaluating unacceptable members and seismic performance) (§ 8-706.2.1) .
Common mistakes
- Assuming any historic concrete can remain without testing or professional evaluation. The CHBC requires the architect or engineer to assign strength values based on tests or historical data (§ 8-808.1) .
- Ignoring bond and development lengths — you must determine these from tests or historical information; they are essential when reinforcement or connection performance is nonstandard (§ 8-808.1) .
- Overlooking detailing deviations: designers sometimes fail to assess how missing confinement, lap splice length, or poor anchorage reduce ductility and reserve strength (§ 8-808.2) .
- Assigning strength values larger than justified by tests or historic comparison — the CHBC cautions that assigned values shall not exceed those provided in related sections without testing and concurrence (§ 8-802) .
Worked example — concrete scenario (illustrative)
Scenario: An 1890 foundation is rubble concrete with suspected low compressive strength. You are the owner preparing repair/rehab documents.
- Inventory & sampling: The structural survey documents the rubble concrete in place and collects representative samples for compressive testing and petrographic inspection (per CHBC guidance that an architect/engineer shall assign values based on testing) (§ 8-808.1) .
- Testing: Laboratory tests show an average compressive strength of, say, 700 psi (illustrative number only — CHBC does not set a limit). Using those results, the engineer assigns an allowable strength and documents assumptions and factors of safety per CHBC requirements (§ 8-808.1) .
- Bond/development: Because the original construction used short embedment and no modern development, the engineer either accepts reduced capacity only where justified by historic tests or designs supplemental anchorage/anchors; bond and development lengths are determined from tests or historical information (§ 8-808.1) .
- Detailing evaluation: The engineer reviews regular-code detailing (splices, confinement, ductility) and concludes some elements lack required detailing; they then evaluate whether reserve strength and ductility are sufficient or if strengthening is needed (§ 8-808.2) .
- Outcome: If testing and evaluation show acceptable capacity for the required loads and no life‑safety collapse risk, the rubble concrete may remain with documented assigned strengths; otherwise retrofit or replacement is required (see also CHBC guidance on unacceptable members) (§ 8-706.2.1, § 8-808.1, § 8-808.2) .
Note: the numeric strength in step 2 is illustrative only. The CHBC requires the design professional to base decisions on tests or historical data rather than fixed CHBC numeric thresholds (§ 8-808.1) .
Related provisions (CHBC)
- § 8-802 — General engineering approaches for archaic materials; assignment of strength values and testing requirements .
- § 8-801.3 — Scope: archaic materials present in historical structures may remain or be reinstalled to match existing conditions .
- § 8-703 — Structural survey (referenced procedure for investigating archaic materials) — see CHBC chapter on structural survey for documentation requirements (structural survey referenced in § 8-802) .
- § 8-706.2 / 8-706.2.1 — Existing building performance and evaluation of members whose failure could lead to collapse; unacceptable members must be strengthened .
- § 8-803 — Nonstructural archaic materials (if the historic concrete is purely nonstructural, different considerations may apply) .
Code references
Grounded in the retrieved California Historical Building Code — click a citation to read the verbatim passage:
CHBC § 8-807.3 High relevance — show source text
8-807.3 Existing wood framing. Existing wood framing members may be assigned allowable stresses consistent with codes in effect at the time of construction. Existing or new replacement wood framing may be of archaic types originally used if properly researched, such as balloon and single wall. Wood joints such as dovetail and mortise and tenon types may be used structurally, provided they are well made. Lumber selected for use and type need not bear grade marks, and greater or lesser species such as low-level pine and fir, boxwood and indigenous hardwoods and other variations may be used for specific conditions where they were or would have been used.
Wood fasteners such as square or cut nails may be used with a maximum increase of 50 percent over wire nails for shear.
SECTION 8-808 — CONCRETE
8-808.1 Materials. Natural cement concrete, unreinforced rubble concrete and similar materials may be utilized wherever that material is used historically. Concrete of low strength and with less reinforcement than required by the regular code may remain in place. The architect or engineer shall assign appropriate values of strength based on testing of samples of the materials. Bond and development lengths shall be determined based on historical information or tests.
8-808.2 Detailing. The architect or engineer shall carefully evaluate all detailing provisions of the regular code which are not met and shall consider the implications of these variations on the ultimate performance of the structure, giving due consideration to ductility and reserve strength.
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ARCHAIC MATERIALS AND METHODS OF CONSTRUCTION
SECTION 8-809 — STEEL AND IRON
The hand-built, untested use of wrought or black iron, the use of cast iron or grey iron, and the myriad of joining methods that are not specifically allowed by code may be used wherever applicable and wherever they have proven their worth under the considerable span of years involved with most qualified historical buildings or structures. Uplift capacity should be evaluated and strengthened where necessary. Fixed conditions or midheight lateral loads on cast iron columns that could cause failure should be taken into account. Existing structural wrought, forged steel or grey iron may be assigned the maximum working stress prevalent at the time of original construction.
SECTION 8-810 — HOLLOW CLAY TILE
The historical performance of hollow clay tile in past earthquakes shall be carefully considered in evaluating walls of hollow clay tile construction. Hollow clay tile bearing walls shall be evaluated and strengthened as appropriate for lateral loads and their ability to maintain support of gravity loads. Suitable protective measures shall be provided to prevent blockage of exit stairways, stairway enclosures, exit ways and public ways as a result of an earthquake.
SECTION 8-811 — VENEERS
8-811.1 Terra cotta and stone. Terra cotta, cast stone and natural stone veneers shall be investigated for the presence of suitable anchorage. Steel anchors shall be investigated for deterioration or corrosion. New or supplemental anchorage shall be provided as appropriate.
8-811.2 Anchorage. Brick veneer with mechanical anchorage at spacings greater than required by the regular code may remain, provided the anchorages have not corroded. Nail strength in withdrawal in wood sheathing may be utilized to its capacity in accordance with code values.
SECTION 8-812 — GLASS AND GLAZING
CHBC § 8-806.4 High relevance — show source text
8-806.4 Nonload-bearing adobe. Nonload-bearing adobe partitions and gable end walls shall be evaluated for stability and anchored against out-of-plane failure if necessary.
8-806.5 Bond beam. Where provided, a bond beam or equivalent structural element shall be located at the top of all adobe walls, and at the second floor for two-story buildings or structures. The size and configuration of the structural element shall be sufficient to provide an effective brace for the wall, to tie the building together and to connect the wall to the floor or roof.
8-806.6 Repair or reconstruction. Repair or reconstruction of wall area may utilize unstabilized brick or adobe masonry designed to be compatible with the constituents of the existing adobe materials.
8-806.7 Shear values. Existing adobe may be allowed a maximum strength level of 12 pounds per square inch (82.7 kPa) for shear.
8-806.8 Mortar. Mortar may be of the same soil composition as that used in the existing wall, or in new walls as necessary to be compatible with the adobe brick.
SECTION 8-807 — WOOD
8-807.1 Existing wood diaphragms or walls. Existing wood diaphragms or walls of straight or diagonal sheathing shall be assigned shear resistance values appropriate with the fasteners and materials functioning in conjunction with the sheathing. The structural survey shall determine fastener details and spacings and verify a load path through floor construction. Shear values of Tables 8-8-A and 8-8-B.
8-807.2 Wood lath and plaster. Wood lath and plaster walls and ceilings may be utilized using the shear values referenced in Section 8-807.1.
8-807.3 Existing wood framing. Existing wood framing members may be assigned allowable stresses consistent with codes in effect at the time of construction. Existing or new replacement wood framing may be of archaic types originally used if properly researched, such as balloon and single wall. Wood joints such as dovetail and mortise and tenon types may be used structurally, provided they are well made. Lumber selected for use and type need not bear grade marks, and greater or lesser species such as low-level pine and fir, boxwood and indigenous hardwoods and other variations may be used for specific conditions where they were or would have been used.
Wood fasteners such as square or cut nails may be used with a maximum increase of 50 percent over wire nails for shear.
SECTION 8-808 — CONCRETE
8-808.1 Materials. Natural cement concrete, unreinforced rubble concrete and similar materials may be utilized wherever that material is used historically. Concrete of low strength and with less reinforcement than required by the regular code may remain in place. The architect or engineer shall assign appropriate values of strength based on testing of samples of the materials. Bond and development lengths shall be determined based on historical information or tests.
8-808.2 Detailing. The architect or engineer shall carefully evaluate all detailing provisions of the regular code which are not met and shall consider the implications of these variations on the ultimate performance of the structure, giving due consideration to ductility and reserve strength.
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ARCHAIC MATERIALS AND METHODS OF CONSTRUCTION
SECTION 8-809 — STEEL AND IRON
CHBC § 8-801 Medium relevance — show source text
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
Where nonstructural historical materials exist in uses which do not meet the requirements of the regular code, their continued use is allowed by this code, provided that any public health and life safety hazards are mitigated subject to the concurrence of the enforcing agency.
SECTION 8-804 — ALLOWABLE CONDITIONS FOR SPECIFIC MATERIALS
Archaic materials which exist and are to remain in qualified historical buildings or structures shall be evaluated for their condition and for loads required by this code. The structural survey required in Section 8-703 of the CHBC shall document existing conditions, reinforcement, anchorage, deterioration and other factors pertinent to establishing allowable stresses, strength levels and adequacy of the archaic materials. The remaining portion of this chapter provides additional specific requirements for commonly encountered archaic materials.
SECTION 8-805 — MASONRY
For adobe, see Section 8-806.
8-805.1 Existing solid masonry. Existing solid masonry walls of any type, except adobe, may be allowed, without testing, a maximum ultimate strength of 9 pounds per square inch (62.1 kPa) in shear where there is a qualifying statement by the architect or engineer that an inspection has been made, that mortar joints are filled and that both brick and mortar are reasonably good. The shear stress above applies to unreinforced masonry, except adobe, where the maximum ratio of unsupported height or length to thickness does not exceed 13, and where minimum quality mortar is used or exists. Wall height or length is measured to supporting or resisting elements that are at least twice as stiff as the tributary wall. Stiffness is based on the gross section. Shear stress may be increased by the addition of 10 percent of the axial direct stress due to the weight of the wall directly above.
CHBC § 405.5.2 Medium relevance — show source text
- Blended cement shall meet ASTM C595, Standard Specification for Blended Hydraulic Cement or ASTM C1157, Standard Performance Specification for Hydraulic Cement.
- Other Hydraulic Cements shall meet ASTM C1157, Standard Performance Specification for Hydraulic Cement.
A5.405.5.2 Concrete. Use concrete manufactured with cementitious materials in accordance with Section A5.405.2, as approved by the Engineer of Record.
A5.405.5.2.1 Supplementary cementitious materials (SCM). Use concrete made with one or more supplementary cementitious materials (SCM) conforming to the following standards:
Fly ash conforming to ASTM C618, Specification for Coal Fly Ash and Raw or Calcined Natural Pozzolan for Use in Concrete.
Slag cement (GGBFS) conforming to ASTM C989, Specification for Use in Concrete and Mortars.
Silica fume conforming to ASTM C1240, Specification for Silica Fume Used in Cementitious Mixtures.
Natural pozzolan conforming to ASTM C618, Specification for Coal Fly Ash and Raw or Calcined Natural Pozzolan for Use in Concrete.
Blended supplementary cementitious materials conforming to ASTM C1697, Standard Specification for Blended Supplementary Cementitious Materials. The amount of each SCM in the blend will be used separately in calculating Equation A5.4-1. Class C fly ash, if used in the blend, will be considered SL for the purpose of satisfying the equation.
Ultra-fine fly ash (UFFA) conforming to ASTM C618, Specification for Coal Fly Ash and Raw or Calcined Natural Pozzolan for Use in Concrete, and the following chemical and physical requirements:
Chemical Requirements Percent Sulfur Trioxide (SO3) 1.5 max. Loss on ignition 1.2 max. Available Alkalines (as Na2O) equivalent 1.5 max. Physical Requirements Percent Particle size distribution
Less than 3.5 microns
Less than 9.0 microns50
90Strength Activity Index with portland cement
7 days
28 days95 (minimum % of control)
110 (minimum % of control)Expansion at 16 days when testing job materials in conformance with ASTM C1567* 0.10 max. * In the test mix, cement shall be replaced with at least 12% UFFA by weight. * In the test mix, cement shall be replaced with at least 12% UFFA by weight. - Metakaolin conforming to ASTM C618, Specification for Coal Fly Ash and Raw or Calcined Natural Pozzolan for Use in Concrete, and the following chemical and physical requirements:
Chemical Requirements Percent Silicon Dioxide (SiO2) + Aluminum Oxide (Al2O3) 92.0 min. Calcium Oxide (CaO) 1.0 max. Sulfur Trioxide (SO3) 1.0 max. Loss on ignition 1.2 max. Available Alkalines (as Na2O) equivalent 1.0 max. Physical Requirements Percent Particle size distribution
Less than 45 microns95 Strength Activity Index with portland cement
7 days
28 days100 (minimum % of control)
100 (minimum % of control)CHBC § 8-706.3 Medium 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.
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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 § 92.0 Medium relevance — show source text
- Metakaolin conforming to ASTM C618, Specification for Coal Fly Ash and Raw or Calcined Natural Pozzolan for Use in Concrete, and the following chemical and physical requirements:
Chemical Requirements Percent Silicon Dioxide (SiO2) + Aluminum Oxide (Al2O3) 92.0 min. Calcium Oxide (CaO) 1.0 max. Sulfur Trioxide (SO3) 1.0 max. Loss on ignition 1.2 max. Available Alkalines (as Na2O) equivalent 1.0 max. Physical Requirements Percent Particle size distribution
Less than 45 microns95 Strength Activity Index with portland cement
7 days
28 days100 (minimum % of control)
100 (minimum % of control)- Ground-glass pozzolan per ASTM C1866/C1866M.
- Other materials with comparable or superior environmental benefits, as approved by the Engineer of Record.
A5.405.5.2.1.1 Mix design equation. Use any combination of one or more SCM, satisfying Equation A5.4-14. When ASTM C595 or ASTM C1157 cement is used, the amount of SCM in these cements shall be used in calculating Equation A5.4-14.
Exception: Minimums in mix designs approved by the Engineer of Record may be lower where high early strength is needed for concrete products or to meet an accelerated project schedule. High early strength shall be defined as outlined in ACI CT.
(Equation A5.4-14) F/ 25 + SL/ 50 + UF /12 ≥ 1
where:
F = Fly ash, natural pozzolan or other approved SCM, or blended SCM, as a percent of total cementitious material for concrete on the project.
APPENDIX A5-28 2025 CALIFORNIA GREEN BUILDING STANDARDS CODE
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APPENDIX A5 — NONRESIDENTIAL VOLUNTARY MEASURES
SL = GGBFS, as a percent of total cementitious material for concrete on the project.
UF = Silica fume, metakaolin or UFFA, as a percent of total cementitious material for concrete on the project.
A5.405.5.3 Concrete manufacture. The following measures shall be permitted in the manufacture of concrete, as approved by the Engineer of Record.
A5.405.5.3.1 Recycled aggregates. Concrete made with one or more of the following materials:
- Blast furnace slag as a lightweight aggregate in unreinforced concrete.
- Recycled concrete aggregate (RCA) or crushed concrete aggregate (CCA) that meets grading requirements of ASTM C33, Standard Specification for Concrete Aggregates. a. Recycled concrete aggregate (RCA) is created from existing concrete structures, including building foundations, parking areas, and sidewalks. It has been processed to create a recycled concrete aggregate usable in many applications. b. Crushed concrete aggregate (CCA) is created by taking concrete that was batched but not used in initial construction and is returned in the mixer truck to the concrete batch plant. As a recent mix and unplaced, it is a clean product with known properties.
- Other materials with comparable or superior environmental benefits.
CHBC § 8-706.1.3 Medium relevance — show source text
Exceptions:
- 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.
- 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.
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8-8 ARCHAIC MATERIALS AND METHODS OF CONSTRUCTION
SECTION 8-801 — PURPOSE, INTENT AND SCOPE
CHBC § 405.4.5 Medium relevance — show source text
Note: If the manufacturer does not separately identify the preconsumer and postconsumer recycled content of a material but reports it as a total single percentage, the total amount shall be considered preconsumer recycled material.
A5.405.4.5 Alternate method for concrete. When Supplementary Cementitious Materials (SCMs), such as fly ash or ground blast furnace slag cement, are used in concrete, an alternate method of calculating and reporting recycled content in concrete products shall be permitted. When determining the recycled content value, the percent recycled content shall be multiplied by the cost of the cementitious materials only, not the total cost of the concrete.
A5.405.5 Cement and concrete. Cement and concrete made with recycled products shall comply with Section A5.405.
A5.405.5.1 Cement. Cement shall comply with one of the following standards:
- Portland cement shall meet ASTM C150, Standard Specification for Portland Cement.
2025 CALIFORNIA GREEN BUILDING STANDARDS CODE APPENDIX A5-27
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APPENDIX A5 — NONRESIDENTIAL VOLUNTARY MEASURES
- Blended cement shall meet ASTM C595, Standard Specification for Blended Hydraulic Cement or ASTM C1157, Standard Performance Specification for Hydraulic Cement.
- Other Hydraulic Cements shall meet ASTM C1157, Standard Performance Specification for Hydraulic Cement.
A5.405.5.2 Concrete. Use concrete manufactured with cementitious materials in accordance with Section A5.405.2, as approved by the Engineer of Record.
A5.405.5.2.1 Supplementary cementitious materials (SCM). Use concrete made with one or more supplementary cementitious materials (SCM) conforming to the following standards:
Fly ash conforming to ASTM C618, Specification for Coal Fly Ash and Raw or Calcined Natural Pozzolan for Use in Concrete.
Slag cement (GGBFS) conforming to ASTM C989, Specification for Use in Concrete and Mortars.
Silica fume conforming to ASTM C1240, Specification for Silica Fume Used in Cementitious Mixtures.
Natural pozzolan conforming to ASTM C618, Specification for Coal Fly Ash and Raw or Calcined Natural Pozzolan for Use in Concrete.
Blended supplementary cementitious materials conforming to ASTM C1697, Standard Specification for Blended Supplementary Cementitious Materials. The amount of each SCM in the blend will be used separately in calculating Equation A5.4-1. Class C fly ash, if used in the blend, will be considered SL for the purpose of satisfying the equation.
Ultra-fine fly ash (UFFA) conforming to ASTM C618, Specification for Coal Fly Ash and Raw or Calcined Natural Pozzolan for Use in Concrete, and the following chemical and physical requirements:
CHBC § 2512.8.2 Medium relevance — show source text
2512.8.2 Curing. Curing of the first coat is permitted to be omitted and the second coat shall be cured as set forth in ASTM C926 and Table 2512.6.
2512.9 Finish coats. Cement plaster finish coats shall be applied over base coats that have been in place for the time periods set forth in ASTM C926. The third or finish coat shall be applied with sufficient material and pressure to bond and to cover the brown coat and shall be of sufficient thickness to conceal the brown coat.
SECTION 2513—EXPOSED AGGREGATE PLASTER
2513.1 General. Exposed natural or integrally colored aggregate is permitted to be partially embedded in a natural or colored bedding coat of cement plaster or gypsum plaster, subject to the provisions of this section.
2513.2 Aggregate. The aggregate shall be applied manually or mechanically and shall consist of marble chips, pebbles or similar durable, moderately hard (three or more on the Mohs hardness scale), nonreactive materials.
2513.3 Bedding coat proportions. The bedding coat for interior or exterior surfaces shall be composed of one part Portland cement and one part Type S lime; or one part blended cement and one part Type S lime; or masonry cement; or plastic cement and not more than three parts of graded white or natural sand by volume. The bedding coat for interior surfaces shall be composed of 100 pounds (45.4 kg) of neat gypsum plaster and not more than 200 pounds (90.8 kg) of graded white sand. A factory-prepared bedding coat for interior or exterior use is permitted. The bedding coat for exterior surfaces shall have a minimum compressive strength of 1,000 pounds per square inch (6895 kPa).
2513.4 Application. The bedding coat is permitted to be applied directly over the first (scratch) coat of plaster, provided that the ultimate overall thickness is not less than [7] / 8 inch (22 mm), including lath. Over concrete or masonry surfaces, the overall thickness shall be not less than [1] / 2 inch (12.7 mm).
2513.5 Bases. Exposed aggregate plaster is permitted to be applied over concrete, masonry, cement plaster base coats or gypsum plaster base coats installed in accordance with Section 2511 or 2512.
2513.6 Preparation of masonry and concrete. Masonry and concrete surfaces shall be prepared in accordance with the provisions of Section 2510.7.
2513.7 Curing of base coats. Cement plaster base coats shall be cured in accordance with ASTM C926. Cement plaster bedding coats shall retain sufficient moisture for hydration (hardening) for 24 hours minimum or, where necessary, shall be kept damp for 24 hours by light water spraying.
SECTION 2514—REINFORCED GYPSUM CONCRETE
2514.1 General. Reinforced gypsum concrete shall comply with the requirements of ASTM C317 and ASTM C956.
Exception: [DSA-SS and OSHPD 1, 1R, 2, 4 & 5] Reinforced gypsum concrete shall be considered as an alternative system, except for
[OSHPD 2] single-story Type V skilled nursing or intermediate care facilities utilizing wood-frame or light-steel-frame construction.
CHBC § 5.2.3.4 Medium relevance — show source text
5.2.3.4_|||X||||X|||||||||||||||||| |907.5.2.4|||X|||||||||||||||||||||| |907.5.2.5|||X|||||||||||||||||||||| |907.6|||X|||||||||||||||||||||| |907.6.1||||X|X|||||||||||||||||||| |907.6.1.1|||X|||||||||||||||||||||| |907.6.4|||X|||||||||||||||||||||| |907.6.4.1|||X|||||||||||||||||||||| |907.6.4.1.1|||X|||||||||||||||||||||| |907.6.4.2|||X|||||||||||||||||||||| |907.6.4.3|||X|||||||||||||||||||||| |907.6.4.4|||X|||||||||||||||||||||| |907.6.6|||X|||||||||||||||||||||| |907.6.6.4|||X|||||||||||||||||||||| |908.2|||X|||||||||||||||||||||| |909.5.3|||X|||||||||||||||||||||| |909.5.3.1|||X|||||||||||||||||||||| |909.12.1|||X|||||||||||||||||||||| |909.13.1|||X|||||||||||||||||||||| |909.16|||X|||||||||||||||||||||| |909.16.1|||X|||||||||||||||||||||| |909.18.9|||X|||||||||||||||||||||| |909.20|||X||||||||||||||||||||||
9-4 2025 CALIFORNIA BUILDING CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
CALIFORNIA BUILDING CODE – MATRIX ADOPTION TABLE
CHAPTER 9 – FIRE PROTECTION AND LIFE SAFETY SYSTEMS—continued
CHBC § 12.1 Medium relevance — show source text
12.1|||X|||||||||||||||||||||| |1705.12.2|||X|||||||||||||||||||||| |1705.13.1.1|||||||||||X|X|||X|||||||||| |1705.13.1.2|||||||||||X|X|||X|||||||||| |1705.13.2|||X|||||||||||||||||||||| |1705.13.3|||X|||||||||||||||||||||| |1705.14.1.1|||||||||||X|X|||X|||||||||| |1705.14.1.2|||||||||||X|X|||X|||||||||| |1705.14.2|||||||||||X|X|||X|||||||||| |1705.14.3.1|||||||||||X|X|||X|||||||||| |1705.15|||X|||||||||||||||||||||| |1705.16|||X|||||||||||||||||||||| |1705.18|||X||||||||X|X|||X|||||||||| |1705.19_ –_1705.20|||X|||||||||||||||||||||| |1707.1|X|||X|X|||||||||||||||||||| |1710|||||||||||X|X|||X||||||||||
The state agency does not adopt sections identified with the following symbol: The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.
17-2 2025 CALIFORNIA BUILDING CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
17 SPECIAL INSPECTIONS AND TESTS
User notes:
About this chapter: Chapter 17 provides a variety of procedures and criteria for testing materials and assemblies, and labeling materials and assemblies. Its key purposes are to establish where additional inspections/observations and testing must be provided, and the submittals and verifications that must be provided to the building official. This chapter expands on the inspections of Chapter 1 by requiring special inspection by a qualified individual where indicated and, in some cases, structural observation by a registered design professional. Quality assurance measures that verify proper assembly of structural components and the suitability of the installed materials are intended to provide a building that, once constructed, complies with the minimum structural and fire-resistance code requirements as well as the approved design. To determine this compliance often requires frequent inspections and testing at specific stages of construction.
ICC code development note: Code change proposals to sections preceded by the designation [BF] will be considered by the IBC—Fire Safety Code Development Committee during the 2024 (Group A) Code Development Cycle. Sections preceded by the designation [F] will be considered by the International Fire Code Development Committee during the 2024 (Group A) Code Development Cycle. All other code change proposals will be considered by the IBC—Structural Code Development Committee during the Group B cycle.
SECTION 1701—GENERAL
1701.1 Scope. The provisions of this chapter shall govern the quality, workmanship and requirements for materials covered. Materials of construction and tests shall conform to the applicable standards listed in this code.
1701.1.1 Application. [OSHPD] The scope of application of Chapter 17 is as follows:
CHBC § 73.4 Medium relevance — show source text
Moist cure the specimens for seven days at 73.4°F (40.8°C) plus or minus 3°F_ (1.7°C). At the age of seven days, remove the specimens from the moist condition and store in a temperature of 73.4°F (40.8°C) plus or minus 3°F (1.7°C) and a relative humidity of 50 plus or minus 10 percent for 21 days; remove and air dry until the time of test at 28 days. The compressive strength test shall be in accordance with ASTM C39, Compressive Strength of Cylindrical Concrete Specimens. Determine the air-dry-unit weight at 28 days. 2. Regardless of the provisions of Subsections 4.1 and 4.2 in Section 4 of Bulletin No. 65, relating to placing, finishing and curing, the following shall apply to these regulations. 2.1. The concrete shall be placed, finished and cured to produce a level, smooth surface. The concrete shall be placed in a single layer to a minimum thickness of 1 [1] / 2 inches (38 mm). The deviation from a plan shall not exceed [1] / 4 inch (6 mm) in any 10 feet (3048 mm). The final finish of the concrete shall be suitable for the applica- tion of the specified wear- resistant covering. Cracks wider than [1] / 8 inch (3 mm) shall be repaired. 2.2. Install a water-resistant membrane between wood or plywood subfloors and the cellular concrete to prevent leakage of the concrete and wetting of the subfloor. The membrane shall consist of waterproof paper or plastic sheets conforming to ASTM C171, Sheet Materials for Curing Concrete, or Type 15 roofing felt conform- ing to ASTM D226, D250 or D227, or Federal Specification UUB790, Building Paper Vegetable Fiber: (Kraft, Waterproofed, Water Repellent and Fire-resistant) Type 1, Grade B. The sheets shall be securely fastened to the subfloor.
2025 CALIFORNIA BUILDING CODE 7-65
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
FIRE AND SMOKE PROTECTION FEATURES
3. Regardless of the provisions of Subsections 6.1 and 6.2 in Section 6, of Bulletin No. 65, relating to applicator qualifica- tions and warranty, these subsections are omitted from this chapter.
SECTION 722—CALCULATED FIRE RESISTANCE
722.1 General. The provisions of this section contain procedures by which the fire resistance of specific materials or combinations of materials is established by calculations. These procedures apply only to the information contained in this section and shall not be otherwise used. The calculated fire resistance of specific materials or combinations of materials shall be established by one of the following:
- Concrete, concrete masonry and clay masonry assemblies shall be permitted in accordance with ACI 216.1/TMS 0216.
- Precast and precast, prestressed concrete assemblies shall be permitted in accordance with PCI 124.
- Steel assemblies shall be permitted in accordance with Chapter 5 of ASCE 29.
- Exposed wood members and wood decking shall be permitted in accordance with Chapter 16 of ANSI/AWC NDS.
Frequently asked questions
Can any piece of historic concrete stay in place without testing?
No. The CHBC requires the project’s architect or engineer to assign appropriate strength values based on testing or historical data and to document their findings (§ 8-808.1) .
Does the CHBC give numeric minimum strengths for low‑strength concrete?
No. § 8-808.1 does not set numeric thresholds — it requires testing or historical documentation and that the design professional assign allowable values based on those tests or comparisons (§ 8-808.1) .
Who decides whether historic concrete detailing is acceptable?
The architect or engineer in responsible charge evaluates deviations from regular-code detailing, considering ductility and reserve strength, and decides if the element may remain or needs strengthening (§ 8-808.2) .
If reinforcement or bond is inadequate, what does the CHBC require?
Bond and development lengths “shall be determined based on historical information or tests,” and inadequate detailing must be evaluated for consequences to ultimate performance; strengthening or supplemental anchorage should be designed where necessary (§ 8-808.1, § 8-808.2) .
Is the enforcing agency involved?
Yes — assigned strength values and departures from regular code are subject to the enforcing agency’s concurrence under the CHBC general engineering approach (§ 8-802) .
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