CHBC · California Historical Building Code
How are historic steel/iron, hollow clay tile, veneers and glazing handled under CHBC?
Under the CHBC, historic steel/iron, hollow clay tile, veneers and original glazing can usually be kept if a qualified architect/engineer inspects them, documents condition, and designs needed strengthening, anchorage or protective measures (see §§ 8-809, 8-810, 8-811, 8-812).
Last reviewed: July 6, 2026
What the code requires — 2-4 sentences
The CHBC permits the retention or reuse of historical steel/iron, hollow clay tile, veneers and original glazing when they are investigated, documented and, where necessary, evaluated and strengthened rather than replaced. Key requirements are: evaluate historic materials for continued capacity (including uplift and lateral resistance), investigate and repair or supplement anchorage, and provide protective measures for glazing in areas subject to human impact — see § 8-809, § 8-810, § 8-811, and § 8-812.
Historic materials may remain when a qualified architect/engineer documents condition and provides strengthening, anchorage, or protective measures as appropriate under the CHBC.
Requirements in detail
Steel and iron (what to check and what you may do)
- The CHBC allows the use or retention of wrought, black, cast or grey iron and historic joining methods where they have proven satisfactory historically. Uplift capacity and conditions that could cause failure (for example fixed conditions or midheight lateral loads on cast-iron columns) must be evaluated and strengthened where necessary. Existing structural wrought, forged steel or grey iron may be assigned the maximum working stress prevalent at the time of original construction. § 8-809.
- Who does it: the evaluation is performed by the project architect or structural engineer familiar with historic structures and documented per the CHBC survey requirements. § 8-703.
Hollow clay tile (bearing walls and egress safety)
- The historic seismic performance of hollow clay tile must be considered; bearing walls of hollow clay tile require evaluation for lateral loads and the ability to maintain support of gravity loads. Strengthening is required “as appropriate.” Also provide protective measures to prevent earthquake-induced blockage of exit stairs, stairway enclosures, exit ways and public ways. § 8-810.
Veneers (anchorage and corrosion)
- Terra cotta, cast stone and natural stone veneers must be investigated for presence of suitable anchorage; steel anchors must be checked for deterioration or corrosion and new or supplemental anchorage provided as appropriate. § 8-811.1.
- Brick veneer with mechanical anchorage at spacings greater than required by the regular code may remain provided the anchorages have not corroded; nail withdrawal strength in wood sheathing may be used per code values. § 8-811.2.
Glass and glazing (human impact and fire-rated systems)
- Historical glazing located where it can be subject to human impact may be approved with the enforcing agency’s concurrence provided alternative protective measures are used (examples listed: additional glazing panels, protective film, guards, systems, devices or signs). § 8-812.1.
- For glazing that is part of fire-rated systems, the CHBC refers to the regular-code provision § 8-402.3 (follow that section for fire-rated glazing requirements). § 8-812.2.
Decision table — at-a-glance (what to ask / measure)
| Material | Decision-relevant dimension(s) | Typical required action(s) | Code Reference |
|---|---|---|---|
| Steel / Iron | Uplift capacity, fixed or midheight lateral loads, evidence of historic working stress | Evaluate; strengthen uplift/anchorage; assign historic working stress where appropriate | § 8-809 |
| Hollow clay tile | Bearing-wall lateral capacity; ability to support gravity loads; risk of blocking exits | Structural evaluation; strengthen as appropriate; provide egress-protective measures | § 8-810 |
| Veneers (terra cotta/stone) | Presence/condition of anchors; corrosion/deterioration of steel anchors | Investigate anchorage; repair or add supplemental anchors | § 8-811.1 |
| Brick veneer | Anchor spacing vs. regular code; corrosion | May remain if anchors not corroded; use nail-withdrawal capacity where applicable | § 8-811.2 |
| Glazing (human impact areas) | Occupant exposure / human-impact risk | Approve only with enforcing-agency concurrence and protective measures (film, guards, signs) | § 8-812.1 |
| Glazing (fire-rated) | Fire-rated assembly requirement | Follow fire-rated glazing provisions — see § 8-402.3 | § 8-812.2 |
Exceptions & special cases
- Brick veneer installed with anchors at spacings greater than regular code may remain if anchors are not corroded — this is an explicit CHBC allowance (see § 8-811.2) rather than a blanket waiver.
- Historic joinery and archaic materials (e.g., hand-built wrought or black iron, cast iron) may be used when they have “proven their worth” historically, but structural weaknesses such as uplift or midheight loads that could cause failure must be addressed — § 8-809.
- Historical glazing in locations subject to human impact can be retained if an enforcing agency concurs and alternative protective measures are provided — approval is discretionary and conditional. § 8-812.1.
Common mistakes
- Assuming historic anchors or iron components are acceptable without checking for corrosion or uplift vulnerability (CHBC requires investigation and strength/anchorage fixes where appropriate). § 8-811.1, § 8-809.
- Treating hollow clay tile bearing walls as nonstructural — the CHBC explicitly requires evaluation for lateral and gravity support and actions to prevent stairway blockage. § 8-810.
- Replacing original glazing without first seeking enforcing-agency concurrence or considering protective alternatives for human-impact locations. § 8-812.1.
- Skipping the required historic-structure survey and documentation; CHBC requires a structural survey by an architect or engineer knowledgeable in historic structures to inform these decisions. § 8-703.
Worked example — concrete scenario with numbers
Scenario: A 1910 3-story commercial building has:
- Cast-iron columns supporting 2nd- and 3rd-floor timber framing.
- Exterior 8" hollow clay tile bearing walls.
- Terra cotta veneer anchored to backup masonry with original steel anchors.
- Original single-pane glazing at an interior stair landing (where people pass).
Apply CHBC rules:
Steel/iron: Evaluate the uplift capacity of the cast-iron columns and check for conditions that could create midheight lateral loads (e.g., infill that restrains lateral movement). If analysis shows insufficient uplift resistance (calculated uplift > available capacity), provide supplemental anchorage or tie-downs. Assign allowable stresses in calculations consistent with the maximum working stress prevalent at time of construction if supported by documentation. See § 8-809.
Hollow clay tile: Perform lateral-load evaluation (seismic shear and overturning capacity) for the 8-inch bearing walls. If analysis indicates lateral capacity is inadequate, design and install appropriate strengthening (e.g., grout/shotcrete infill, steel frames, or discreet anchors) to restore gravity-support continuity and lateral resistance. Also, add measures (for example, anchored barriers or reinforced spandrels) so a post-earthquake collapse of tile cannot block the stairway; this is required for egress safety by § 8-810.
Veneer anchors: Inspect each terra cotta anchor for corrosion. If more than a negligible percentage show section loss or movement, design supplemental anchors spaced to meet the practical anchorage needs while minimizing damage to historic material. If existing mechanical anchors are spaced wider than the regular code would allow but are found uncorroded and engaged, they may remain per § 8-811.2; otherwise replace/supplement per § 8-811.1.
Stair landing glazing: Because the original single-pane glazing is in a human-impact location, obtain the enforcing agency’s concurrence. Propose a protective solution — e.g., apply a clear safety protective film that provides impact resistance or install a discreet guard — and document how the measure preserves appearance. If the enforcing agency accepts the alternative, original glazing may be retained per § 8-812.1.
Document all inspections, analyses and chosen remediation methods in the structural survey report required by § 8-703 (which the CHBC requires for evaluating and designing modifications).
Related provisions
- § 8-703 — Structural survey requirements for historic structures (survey by architect/engineer).
- § 8-802 — General engineering approaches: assign strength values based on similar materials or testing.
- § 8-706.4 / 8-706.5 — Parapets and nonstructural features (evaluation and anchorage of exterior decoration).
- § 8-402.3 — Fire-rated glazing provisions (referenced by § 8-812.2).
Code references
Grounded in the retrieved California Historical Building Code — click a citation to read the verbatim passage:
CHBC § 8-810 High relevance — show source text
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
8-812.1 Glazing subject to human impact. Historical glazing material located in areas subject to human impact may be approved subject to the concurrence of the enforcing agency when alternative protective measures are provided. These measures may include, but not be limited to, additional glazing panels, protective film, protective guards or systems, and devices or signs which would provide adequate public safety.
8-812.2 Glazing in fire-rated systems. See Section 8-402.3.
TABLE8-8A—STRENGTH VALUES FOR EXISTING MATERIALS Col2 EXISTING MATERIALS OR CONFIGURATIONS OF MATERIALS1 STRENGTH LEVEL CAPACITY
x14.594 for N/m1. Horizontal diaphragms2
1.1. Roofs with straight sheathing and roofing applied directly to the sheathing
1.2. Roofs with diagonal sheathing and roofing applied directly to the sheathing
1.3. Floors with straight tongue-and-groove sheathing
1.4. Floors with straight sheathing and finished wood flooring with board edges
offset or perpendicular
1.5. Floors with diagonal sheathing and finished300 lbs per foot for seismic shear
750 lbs per foot for seismic shear
300 lbs per foot for seismic shear
1,500 lbs per foot for seismic shear
1,800 lbs per foot for seismic shear2. Crosswalls2,3
2.1. Plaster on wood or metal lath
2.2. Plaster on gypsum lath
2.3. Gypsum wallboard, unblocked edges
2.4.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 § 1-1.5 High relevance — show source text
Steel columns
and all of
primary
trusses|1-1.5|Siliceous aggregate concrete and concrete excluded in Item
1-1.1, members 8" × 8" or greater.a|21/2|2|1|1| |1. Steel columns
and all of
primary
trusses|1-1.6|Siliceous aggregate concrete and concrete excluded in Item
1-1.1, members 12" × 12" or greater.a|2|1|1|1| |1. Steel columns
and all of
primary
trusses|1-2.1|Clay or shale brick with brick and mortar fill.a|33/4|—|—|21/4| |1. Steel columns
and all of
primary
trusses|1-3.1|4" hollow clay tile in two 2" layers;1/2" mortar between tile
and column;3/ 8" metal mesh 0.046" wire diameter in hori-
zontal joints; tile fill.a|4|—|—|—| |1. Steel columns
and all of
primary
trusses|1-3.2|2" hollow clay tile;3/4" mortar between tile and column;3/8"
metal mesh 0.046" wire diameter in horizontal joints; lime-
stone concrete filla; plastered with3/4" gypsum plaster.|3|—|—|—| |1. Steel columns
and all of
primary
trusses|1-3.3|2" hollow clay tile with outside wire ties 0.08" diameter at
each course of tile or3/8" metal mesh 0.046" diameter wire in
horizontal joints; limestone or trap-rock concrete filla extend-
ing 1" outside column on all sides.|—|—|3|—| |1. Steel columns
and all of
primary
trusses|1-3.4|2" hollow clay tile with outside wire ties 0.08" diameter at
each course of tile with or without concrete fill;3/4" mortar
between tile and column.|—|—|—|2| |1. Steel columns
and all of
primary
trusses|1-4.1|Cement plaster over metal lath wire tied to3/4" cold-rolled
vertical channels with 0.049" (No. 18 B.W. gage) wire ties
spaced 3" to 6" on center. Plaster mixed 1: 21/2 by volume,
cement to sand.|—|—|21/2
b|7/8| |1. Steel columns
and all of
primary
trusses|1-5.1|Vermiculite concrete, 1:4 mix by volume over paper-backed
wire fabric lath wrapped directly around column with addi-
tional 2" × 2" 0.065"/0.065" (No. 16/16 B.W. gage) wire fabric
placed3/4" from outer concrete surface. Wire fabric tied with
0.049" (No. 18B.W. gage) wire spaced 6" on center for inner
layer and 2" on center for outer layer.|2|—|—|—|CHBC § 1-1.1 High relevance — show source text
OF INSULATING MATERIAL**
FOR THE FOLLOWING FIRE-RESISTANCE PERIODS
(inches)| |** STRUCTURAL**
PARTS TO BE
PROTECTED|** ITEM**
NUMBER|** INSULATING MATERIAL USED**|** 4 hours**|** 3 hours**|** 2 hours**|** 1 hour**| |1. Steel columns
and all of
primary
trusses|1-1.1|Carbonate, lightweight and sand-lightweight aggregate
concrete, members 6" × 6" or greater (not including sand-
stone, granite and siliceous gravel).a|21/2|2|11/2|1| |1. Steel columns
and all of
primary
trusses|1-1.2|Carbonate, lightweight and sand-lightweight aggregate
concrete, members 8" × 8" or greater (not including sand-
stone, granite and siliceous gravel).a|2|11/2|1|1| |1. Steel columns
and all of
primary
trusses|1-1.3|Carbonate, lightweight and sand-lightweight aggregate
concrete, members 12" × 12" or greater (not including sand-
stone, granite and siliceous gravel).a|11/2|1|1|1| |1. Steel columns
and all of
primary
trusses|1-1.4|Siliceous aggregate concrete and concrete excluded in Item
1-1.1, members 6" × 6" or greater.a|3|2|11/2|1| |1. Steel columns
and all of
primary
trusses|1-1.5|Siliceous aggregate concrete and concrete excluded in Item
1-1.1, members 8" × 8" or greater.a|21/2|2|1|1| |1. Steel columns
and all of
primary
trusses|1-1.6|Siliceous aggregate concrete and concrete excluded in Item
1-1.1, members 12" × 12" or greater.a|2|1|1|1| |1. Steel columns
and all of
primary
trusses|1-2.1|Clay or shale brick with brick and mortar fill.a|33/4|—|—|21/4| |1. Steel columns
and all of
primary
trusses|1-3.1|4" hollow clay tile in two 2" layers;1/2" mortar between tile
and column;3/ 8" metal mesh 0.046" wire diameter in hori-
zontal joints; tile fill.a|4|—|—|—| |1. Steel columns
and all of
primary
trusses|1-3.2|2" hollow clay tile;3/4" mortar between tile and column;3/8"
metal mesh 0.046" wire diameter in horizontal joints; lime-
stone concrete filla; plastered with3/4" gypsum plaster.|3|—|—|—| |1.CHBC § 8-8 High relevance — show source text
CHAPTER 8-8 ARCHAIC MATERIALS AND METHODS OF
CONSTRUCTION . . . . . . . . . . . . . . . . . . . . . . . 15
Section
8-801 Purpose, Intent and Scope . . . . . . . . . . . . . . . . . . . . . . 15 8-802 General Engineering Approaches. . . . . . . . . . . . . . . . . 15 8-803 Nonstructural Archaic Materials. . . . . . . . . . . . . . . . . . 15
8-804 Allowable Conditions for Specific Materials . . . . . . . 15 8-805 Masonry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 8-806 Adobe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
8-807 Wood . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
8-808 Concrete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
8-809 Steel and Iron . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
8-810 Hollow Clay Tile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
8-811 Veneers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
8-812 Glass and Glazing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
CHAPTER 8-9 MECHANICAL, PLUMBING AND ELECTRICAL REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . 19
Section
8-901 Purpose, Intent and Scope . . . . . . . . . . . . . . . . . . . . . . 19 8-902 Mechanical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
8-903 Plumbing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 8-904 Electrical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
CHAPTER 8-10 QUALIFIED HISTORICAL DISTRICTS,
SITES AND OPEN SPACES . . . . . . . . . . . . . . . 23
Section
CHBC § 0.76 Medium relevance — show source text
The point of uplift shall be taken at 0.76 L from the head of the tile and the middle of the exposed width. For roof tiles with nails or screws (with or without a tail clip), the axis of rotation shall be taken as the head of the tile for direct deck application or as the top edge of the batten for battened applications. For roof tiles fastened only by a nail or screw along the side of the tile, the axis of rotation shall be determined by testing. For roof tiles installed with battens and fastened only by a clip near the tail of the tile, the moment arm shall be determined about the top edge of the batten with consideration given for the point of rotation of the tiles based on straight bond or broken bond and the tile profile.
M a = Aerodynamic uplift moment, feet-pounds (N-mm) acting to raise the tail of the tile. q h = Wind velocity pressure, psf (kN/m [2] ) determined from Section 26.10.2 of ASCE 7.
Concrete and clay roof tiles complying with the following limitations shall be designed to withstand the aerodynamic uplift moment as determined by this section.
- The roof tiles shall be either loose laid on battens, mechanically fastened, mortar set or adhesive set.
- The roof tiles shall be installed on solid sheathing that has been designed as components and cladding.
- An underlayment shall be installed in accordance with Chapter 15.
- The tile shall be single lapped interlocking with a minimum head lap of not less than 2 inches (51 mm).
- The length of the tile shall be between 1.0 and 1.75 feet (305 mm and 533 mm).
- The exposed width of the tile shall be between 0.67 and 1.25 feet (204 mm and 381 mm).
- The maximum thickness of the tail of the tile shall not exceed 1.3 inches (33 mm).
- Roof tiles using mortar set or adhesive set systems shall have not less than two-thirds of the tile’s area free of mortar or adhesive contact.
1609.6.3.2 Tornado loads. Tornado loads on rigid tile roof coverings shall be determined in accordance with Section 1609.6.3.1, replacing q h with q hT and ( GC p ) with K vT ( GC p ) in Equation 16-19, where: q hT = tornado velocity pressure, pounds per square foot (kN/m [2] ) determined in accordance with Section 32.10 of ASCE 7.
K vT = tornado pressure coefficient adjustment factor for vertical winds, determined in accordance with Section 32.14 of ASCE 7.
1609.7 Elevators, escalators and other conveying systems. Elevators, escalators and other conveying systems and their components exposed to outdoor environments shall satisfy the wind design requirements of ASCE 7.
SECTION 1610—SOIL LOADS AND HYDROSTATIC PRESSURE
CHBC § 8-702.2 Medium relevance — show source text
8-702.2 Nothing in these regulations shall prevent voluntary and partial seismic upgrades when it is demonstrated that such upgrades will improve life safety and when a full upgrade would not otherwise be required.
SECTION 8-703 — STRUCTURAL SURVEY
8-703.1 Scope. When a structure or portion of a structure is to be evaluated for structural capacity under the CHBC, it shall be surveyed for structural conditions by an architect or engineer knowledgeable in historical structures. The survey shall evaluate deterioration or signs of distress. The survey shall determine the details of the structural framing and the system for resistance of gravity and lateral loads. Details, reinforcement and anchorage of structural systems and veneers shall be determined and documented where these members are relied on for seismic lateral resistance.
8-703.2 The results of the survey shall be utilized for evaluating the structural capacity and for designing modifications to the structural system to reach compliance with this code.
8-703.3 Historical records. Past historical records of the structure or similar structures may be used in the evaluation, including the effects of subsequent alterations.
SECTION 8-704 — NONHISTORICAL ADDITIONS AND NONHISTORICAL ALTERATIONS
8-704.1 New nonhistorical additions and nonhistorical alterations which are structurally separated from an existing historical building or structure shall comply with regular code requirements.
8-704.2 New nonhistorical additions which impose vertical or lateral loads on an existing structure shall not be permitted unless the affected part of the supporting structure is evaluated and strengthened, if necessary, to meet regular code requirements.
Note: For use of archaic materials, see Chapter 8-8.
SECTION 8-705 — STRUCTURAL REGULATIONS
8-705.1 Gravity loads. The capacity of the structure to resist gravity loads shall be evaluated and the structure strengthened as necessary. The evaluation shall include all parts of the load path. Where no distress is evident, and a complete load path is present, the structure may be assumed adequate by having withstood the test of time if anticipated dead and live loads will not exceed those historically present.
8-705.2 Wind and seismic loads. The ability of the structure to resist wind and seismic loads shall be evaluated. Wind loads shall be considered when appropriate, but need not exceed 75 percent of the wind loads prescribed by the regular code. The evaluation shall be based on the requirements of Section 8-706.
8.705.2.1 Any unsafe conditions in the lateral-load-resisting system shall be corrected, or alternative resistance shall be provided. When strengthening is required, additional resistance shall be provided to meet the minimum requirements of the CHBC. The strengthening measures shall be selected with the intent of meeting the performance objectives set forth in Section 8-701.2. The evaluation of structural members and structural systems for seismic loads shall consider the inelastic performance of structural members and their ability to maintain load-carrying capacity during the seismic loadings prescribed by the regular code.
8.705.2.2 The architect or engineer shall consider additional measures with minimal loss of, and impact to, historical materials which will reduce damage and needed repairs in future earthquakes to better preserve the historical structure in perpetuity. These additional measures shall be presented to the owner for consideration as part of the rehabilitation or restoration.
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STRUCTURAL REGULATIONS
CHBC § 8-810 Medium relevance — show source text
8-810 Hollow Clay Tile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
8-811 Veneers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
8-812 Glass and Glazing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
CHAPTER 8-9 MECHANICAL, PLUMBING AND ELECTRICAL REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . 19
Section
8-901 Purpose, Intent and Scope . . . . . . . . . . . . . . . . . . . . . . 19 8-902 Mechanical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
8-903 Plumbing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 8-904 Electrical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
CHAPTER 8-10 QUALIFIED HISTORICAL DISTRICTS,
SITES AND OPEN SPACES . . . . . . . . . . . . . . . 23
Section
8-1001 Purpose and Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 8-1002 Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 8-1003 Site Relations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
APPENDIX A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
HISTORY NOTE APPENDIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
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8-1 ADMINISTRATION
Note: The California Historical Building Code, Part 8 of Title 24, governs for all qualified historical buildings or properties in the State of California.
SECTION 8-101 — TITLE, PURPOSE AND INTENT
8-101.1 Title. These regulations shall be known as the California Historical Building Code and will be referred to herein as “the CHBC.”
CHBC § 8-7 Medium relevance — show source text
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8-7 STRUCTURAL REGULATIONS
SECTION 8-701 — PURPOSE, INTENT AND SCOPE
8-701.1 Purpose. The purpose of the CHBC is to provide alternative regulations to the regular code for the structural safety of buildings designated as qualified historical buildings or properties. The CHBC requires enforcing agencies to accept any reasonably equivalent alternatives to the regular code when dealing with qualified historical buildings or properties.
8-701.2 Intent. The intent of this chapter is to encourage the preservation of qualified historical buildings or structures while providing standards for a minimum level of building performance with the objective of preventing partial or total structural collapse such that the overall risk of life-threatening injury as a result of structural collapse is low.
8-701.3 Application. The alternative structural regulations provided by Section 8-705 are to be applied in conjunction with the regular code whenever a structural upgrade or reconstruction is undertaken for qualified historical buildings or properties.
SECTION 8-702 — GENERAL
8-702.1 The CHBC shall not be construed to allow the enforcing agency to approve or permit a lower level of safety of structural design and construction than that which is reasonably equivalent to the regular code provisions in occupancies which are critical to the safety and welfare of the public at large, including, but not limited to, public and private schools, hospitals, municipal police and fire stations and essential services facilities.
8-702.2 Nothing in these regulations shall prevent voluntary and partial seismic upgrades when it is demonstrated that such upgrades will improve life safety and when a full upgrade would not otherwise be required.
SECTION 8-703 — STRUCTURAL SURVEY
8-703.1 Scope. When a structure or portion of a structure is to be evaluated for structural capacity under the CHBC, it shall be surveyed for structural conditions by an architect or engineer knowledgeable in historical structures. The survey shall evaluate deterioration or signs of distress. The survey shall determine the details of the structural framing and the system for resistance of gravity and lateral loads. Details, reinforcement and anchorage of structural systems and veneers shall be determined and documented where these members are relied on for seismic lateral resistance.
8-703.2 The results of the survey shall be utilized for evaluating the structural capacity and for designing modifications to the structural system to reach compliance with this code.
8-703.3 Historical records. Past historical records of the structure or similar structures may be used in the evaluation, including the effects of subsequent alterations.
SECTION 8-704 — NONHISTORICAL ADDITIONS AND NONHISTORICAL ALTERATIONS
8-704.1 New nonhistorical additions and nonhistorical alterations which are structurally separated from an existing historical building or structure shall comply with regular code requirements.
8-704.2 New nonhistorical additions which impose vertical or lateral loads on an existing structure shall not be permitted unless the affected part of the supporting structure is evaluated and strengthened, if necessary, to meet regular code requirements.
Note: For use of archaic materials, see Chapter 8-8.
SECTION 8-705 — STRUCTURAL REGULATIONS
CHBC § 323-9843 Medium relevance — show source text
State Librarian [SL]
library.ca.gov csllaw@library.ca.gov (916) 323-9843 Public Library Construction & Renovation
2025 CALIFORNIA HISTORICAL BUILDING CODE v
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
HOW TO DETERMINE WHERE CHANGES HAVE BEEN MADE
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vi 2025 CALIFORNIA HISTORICAL BUILDING CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
PART 8 CONTAINS ALTERNATIVE REGULATIONS
FOR QUALIFIED HISTORICAL BUILDINGS
The California Historical Building Code (CHBC) is unique among state regulations. The authoring of the original CHBC required state agencies promulgating regulations for building construction to work in harmony with representatives of other design and construction disciplines. The result was a totally new approach to building codes for historical structures, which maintains currently acceptable life safety standards. These regulations are also unique in that they are performance oriented rather than prescriptive. The provisions of the CHBC are to be applied by the enforcing authority of every city, county, city and county, or state agency in permitting repairs, alterations and additions necessary for the preservation, rehabilitation, relocation, related construction, change of use or continued use of a qualified historical building. The authority for use of the CHBC is vested in Sections 18950 through 18961 of the Health and Safety Code. Section 18954 states, “The building department of every city or county or other local agency that has jurisdiction over the enforcement of code within its legal authority shall apply the alternative standards and regulations adopted pursuant to Section 18959.5 in permitting repairs, alterations, and additions necessary for the preservation, restoration, rehabilitation, safety, moving, or continued use of a qualified historical building or structure. A state agency shall apply the alternative regulations adopted pursuant to Section 18959.5 in permitting repairs, alterations, and additions necessary for the preservation, restoration, rehabilitation, safety, moving, or continued use of a qualified historical building or structure.” However, be aware that in order to use the CHBC, the structure under consideration must be qualified by being designated as an historical building or structure. Section 18955 states, “For the purposes of this part, a qualified historical building or structure is any structure or property, collection of structures, and their related sites deemed of importance to the history, architecture, or culture of an area by an appropriate local or state governmental jurisdiction. This shall include historical buildings or structures on existing or future national, state or local historical registers or official inventories, such as the National Register of Historic Places, State Historical Landmarks, State Points of Historical Interest, and city or county registers or inventories of historical or architecturally significant sites, places, historic districts, or landmarks. This shall also include places, locations, or sites identified on these historical registers or official inventories and deemed of importance to the history, architecture, or culture of an area by an appropriate local or state governmental jurisdiction.” The regulations of the CHBC have the same authority as state law and are to be considered as such. Liability is the same as for prevailing law. The intent of the CHBC is to save California’s architectural heritage by recognizing the unique construction problems inherent in historical buildings and by providing a code to deal with these problems.
California Historical Building Code Medium relevance — show source text
31/4″ concrete between tiles, including
two1/2″ rebars each with1/2″ concrete cover
and5/8″ filler tiles, between hollow tiles;1/2″
plaster cover, lower.|61 psf|3 hrs
23 min|||7|3, 4, 6|31/3| |F/C-HT-3|6″|Cover: 11/2″ concrete (6280 psi); three-cell
hollow clay tiles, 12″ × 12″ × 4″; 31/4″ concrete
between tiles, including two1/2″ rebars with1/2″
cover;1/2″ plaster cover, lower.|122 psf|2 hrs|||7|1, 3, 5,
8|2| |F/C-HT-4|6″|Cover: 11/2″ concrete (6280 psi); three-cell
hollow clay tiles, 12″ × 12″ × 4″; 31/4″ concrete
between tiles, including two1/2″ rebars with3/4″
cover;1/2″ plaster cover, lower.|115 psf|2 hrs
23 min|||7|1, 3, 7|21/3| |F/C-HT-5|6″|Cover: 11/2″ concrete (6470 psi); three-cell
hollow clay tiles, 12″ × 12″ × 4″; 31/4″ concrete
between tiles, including two1/2″ rebars with1/2″
cover;1/2″ plaster cover, lower.|122 psf|2 hrs|||7|1, 3, 5,
8|2| |F/C-HT-6|8″|Floor cover: 11/2″ gravel cement (4300 psi);
three-cell hollow clay tiles, 12″ × 12″ × 6″; 31/2″
space between tiles, including two1/2″ rebars
with 1″ cover from concrete bottom;1/2″ plaster
cover, lower.|165 psf|4 hrs|||7|1, 3, 9,
10|4| |F/C-HT-7|9″ (nom.)|Deck:7/8″ T&G on 2″ × 11/2″ bottoms (18″ o.c.),
11/2″ concrete cover (4600 psi); three-cell
hollow clay tiles, 12″ × 12″ × 4″; 3″ concrete
between tiles, including one3/4″ rebar3/4″ from
tile bottom;3/4″ plaster cover.|95 psf|2 hrs
26 min|||7|4,
11–13|21/3| |F/C-HT-8|9″ (nom.)|Deck:7/8″ T&G on 2″ × 11/2″ bottoms (18″ o.c.),
11/2″ concrete cover (3850 psi); three-cell
hollow clay tiles, 12″ × 12″ × 4″; 3″ concrete
between tiles, including one3/4″ rebar3/4″ from
tile bottoms;1/2″ plaster cover.|95 psf|3 hrs
28 min|||7|4,
11–13|| |F/C-HT-9|9″ (nom.CHBC § 25.4 Medium relevance — show source text
5,
8|2| |F/C-HT-6|8″|Floor cover: 11/2″ gravel cement (4300 psi);
three-cell hollow clay tiles, 12″ × 12″ × 6″; 31/2″
space between tiles, including two1/2″ rebars
with 1″ cover from concrete bottom;1/2″ plaster
cover, lower.|165 psf|4 hrs|||7|1, 3, 9,
10|4| |F/C-HT-7|9″ (nom.)|Deck:7/8″ T&G on 2″ × 11/2″ bottoms (18″ o.c.),
11/2″ concrete cover (4600 psi); three-cell
hollow clay tiles, 12″ × 12″ × 4″; 3″ concrete
between tiles, including one3/4″ rebar3/4″ from
tile bottom;3/4″ plaster cover.|95 psf|2 hrs
26 min|||7|4,
11–13|21/3| |F/C-HT-8|9″ (nom.)|Deck:7/8″ T&G on 2″ × 11/2″ bottoms (18″ o.c.),
11/2″ concrete cover (3850 psi); three-cell
hollow clay tiles, 12″ × 12″ × 4″; 3″ concrete
between tiles, including one3/4″ rebar3/4″ from
tile bottoms;1/2″ plaster cover.|95 psf|3 hrs
28 min|||7|4,
11–13|| |F/C-HT-9|9″ (nom.)|Deck:7/8″ T&G on 2″ × 11/2″ bottoms (18″ o.c.),
11/2″ concrete cover (4200 psi); three-cell
hollow clay tiles, 12″ × 12″ × 4″; 3″ concrete
between tiles, including one3/4″ rebar3/4″ from
tile bottoms;1/2″ plaster cover.|95 psf|2 hrs
14 min|||7|3, 5, 8,
11|| |F/C-HT-10|51/2″|Fire clay tile (4″ thick); 11/2″ concrete cover; for
general details, see Note 15.|See
Note 14|1 hr|||43|15|1| |F/C-HT-11|8″|Fire clay tile (6″ thick); 2″ cover.|See
Note 14|1 hr|||43|15|1| |F/C-HT-12|51/2″|Fire clay tile (4″ thick); 11/2″ cover;
5/8″ gypsum plaster, lower.|See
Note 14|1 hr
30 min|||43|15|11/2| |F/C-HT-13|8″|Fire clay tile (6″ thick); 2″ cover;
5/8″ gypsum plaster, lower.|See
Note 14|2 hrs|||43|15|11/2|For SI: 1 inch = 25.4 mm, 1 foot = 305 mm, 1 pound per square inch = 0.00689 MPa, 1 pound per square foot = 47.9 N/m [2] .
Frequently asked questions
Can I leave original cast-iron columns in place without any work?
Yes — provided a qualified engineer documents they have sufficient capacity (including uplift and resistance to midheight lateral loads) or designs strengthening where needed; CHBC permits original cast or grey iron when proven by historical performance and evaluation. § 8-809.
Do I have to replace terra cotta anchors if they’re rusty?
Not automatically. The anchors must be investigated for deterioration or corrosion; if corrosion compromises anchorage, new or supplemental anchors are required. § 8-811.1.
Is original single-pane glass allowed in a public stair?
Possibly — glazing in areas subject to human impact can be retained only with enforcing-agency concurrence and if alternative protective measures (film, guards, etc.) are provided. § 8-812.1.
Who must perform the evaluations called for by these sections?
A structural architect or engineer knowledgeable in historic structures must survey and evaluate the structure and document needed strengthening per § 8-703.
If brick veneer anchors are spaced wider than current code, must I change them?
Not necessarily — brick veneers with mechanical anchors at spacings greater than regular code may remain provided the anchors have not corroded; otherwise provide supplemental anchorage. § 8-811.2.
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California Historical Building Code