CHBC · California Historical Building Code

What documentation and survey requirements establish allowable conditions for archaic materials?

Q: Who must sign/stamp the survey report?

An architect or engineer knowledgeable in historical structures must prepare and sign/stamp the structural survey report as required by § 8-703.1 .

Q: Is material testing always required before assigning allowable stresses?

No — testing is required “when applicable.” The architect/engineer may assign values based on similarity to codified materials or tests; assigned values cannot exceed CHBC-prescribed limits without adequate testing and agency concurrence ( § 8-802 , § 8-804 ).

Q: What specific items must the survey document for vaults/veneers?

The survey must document anchorage , reinforcement , and any deterioration affecting seismic lateral resistance or falling hazards; CHBC calls out veneers/anchors specifically in Chapter 8-8 and related veneer sections (see § 8-804 and § 8-811.1 ).

Before you can keep or reuse historic (archaic) materials in a California historic building, a qualified architect or structural engineer must perform a detailed structural survey and produce a stamped report documenting existing condition, anchorage, reinforcement, deterioration and load paths; those findings are the basis for any allowable stress or strength values (CHBC **§ 8-703** and **§ 8-804**).

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Last reviewed: July 6, 2026

What the code requires — 2–4 sentences

The CHBC requires a thorough structural survey performed by an architect or engineer knowledgeable in historical structures and a written record of the survey before assigning allowable stresses or permitting archaic materials to remain. Specifically, § 8-703 mandates the scope and content of the structural survey and § 8-804 requires that the survey document the conditions used to establish allowable stresses, strength levels and adequacy of archaic materials. § 8-703 and § 8-804 .

A qualified professional must survey and document existing conditions — including reinforcement, anchorage, deterioration and load paths — before any allowable stress or strength level for archaic materials is established (see § 8-703 and § 8-804).

Key defined terms (first use)

structural survey — the site evaluation and documentation required by § 8-703.
archaic materials — materials historically used in the building fabric that are dealt with under CHBC (see Chapter 8-8 and § 8-804).
architect or engineer knowledgeable in historical structures — the professional required to carry out the survey per § 8-703.1.

Requirements in detail

Who must do the work

The survey must be carried out by an architect or engineer knowledgeable in historical structures (see § 8-703.1). The professional must evaluate deterioration, signs of distress, and the details of framing and lateral- and gravity-resisting systems. § 8-703.1

What the survey must document

The survey results are used to evaluate capacity and design modifications (§ 8-703.2).
§ 8-804 explicitly requires that the structural survey document: existing conditions, reinforcement, anchorage, deterioration, and other factors pertinent to establishing allowable stresses and strength levels for archaic materials. § 8-804

When testing is needed and who assigns strength values

Testing is required “when applicable”; strength values for archaic materials are assigned by the architect or structural engineer in responsible charge, based on similarity to codified materials or on tests. Assigned values are subject to the enforcing agency’s concurrence and cannot exceed the limits in the CHBC without adequate testing. See § 8-802 and cross-reference in § 8-804. § 8-802 § 8-804

Decision-relevant dimensions and values (quick reference)

Decision factor	What to measure / document	Typical thresholds / values	Code reference
Responsible professional	Confirm the surveyor is an architect or engineer knowledgeable in historical structures	Professional stamp / report prepared by qualified A/E	§ 8-703.1
Survey content	Existing conditions, reinforcement, anchorage, deterioration, framing details, lateral-resisting system, veneers	Full documentary report used for capacity evaluation	§ 8-703.1, § 8-703.2, § 8-804
Trigger for testing	Non‑conforming details, unknown material properties, or when assigned strengths would exceed CHBC limits	“Testing shall be performed when applicable” — use representative sampling / test methods	§ 8-802
Example allowable value (solid masonry shear)	Visual verification of mortar and brick quality, full joints, and height/thickness ratio ≤ 13	Max ultimate shear = 9 psi (62.1 kPa) without testing (for solid masonry, except adobe)	§ 8-805.1
Example allowable value (adobe shear)	Existing adobe evaluated and documented	Max shear = 12 psi (82.7 kPa) per CHBC	§ 8-806.7

(Notes: the CHBC’s Chapter 8-8 contains additional material-specific values and conditions; the survey must record whatever factors are called out for the specific material in Chapter 8-8.)

Required deliverables from the survey (practical checklist)

Written report signed and stamped by the responsible A/E. § 8-703.1
Photographs and sketches showing reinforcement, anchorage, and deterioration locations. § 8-804
Measured framing and veneer details that demonstrate load paths for gravity and lateral forces. § 8-703.1
Test reports where sampling/testing was performed (material tests, pull-out tests, shear tests), if required per § 8-802.

Exceptions & special cases

The CHBC allows the use of historical materials where they present no public health or life-safety hazard; nonstructural archaic materials can remain if hazards are mitigated with enforcing-agency concurrence (see § 8-803).
Where code text in Chapter 8-8 provides material-specific alternate numeric allowances (for example, masonry or adobe limits), those specific provisions apply, but only after the survey documents compliance with the listed conditions (see § 8-805.1, § 8-806.7).
Historical records of the structure and similar structures may be used to inform the evaluation (e.g., original drawings, previous test data), per § 8-703.3.

Common mistakes

Relying on a non‑qualified inspector or un‑stamped reports — the CHBC requires a qualified architect or engineer for the structural survey (§ 8-703.1).
Failing to document anchorage and load path: CHBC places special emphasis on anchorage and details relied on for seismic lateral resistance — omission undermines allowable assignments (§ 8-703.1, § 8-804).
Assigning strength values without testing when the material or configuration exceeds CHBC presumptive limits (e.g., masonry ratios or stated psi limits) — testing is required “when applicable” and assigned values are subject to enforcing-agency concurrence (§ 8-802, § 8-804).
Ignoring veneer anchorage or deterioration in stone/terra cotta veneers — CHBC specifically requires investigation of anchors and corrosion for veneers (§ 8-811.1, cross-referenced by § 8-804).

Worked example — masonry wall left in place

Scenario: A qualified historical building has an existing unreinforced solid brick bearing wall that will remain. The wall is 13 feet unsupported height and 12 inches (1.0 ft) thick; mortar joints appear full and material is in reasonable condition.

Steps tied to CHBC:

Commission an architect or engineer knowledgeable in historical structures to perform the structural survey per § 8-703.1 and document reinforcement, anchorage, deterioration and framing details. § 8-703.1
The survey records: unsupported height = 13 ft, thickness = 1.0 ft → ratio = 13 (meets the CHBC ratio limit in the masonry provision). § 8-805.1
Visual inspection confirms full mortar joints and “reasonably good” brick and mortar. The A/E may then assign the unreinforced solid masonry a maximum ultimate shear strength of 9 psi without additional testing, documenting the basis in the report. § 8-805.1
If any of those conditions were not met (e.g., ratio >13, poorly filled joints, corroded anchors), the engineer would either (a) require representative testing and then assign strength based on tests, or (b) design strengthening measures — consistent with § 8-802 and § 8-804. § 8-802 § 8-804

Related provisions

§ 8-703 — Structural survey scope and use (survey by qualified A/E).
§ 8-804 — Allowable conditions for specific archaic materials; ties survey to allowable stresses.
§ 8-802 — Strength-value assignment and testing guidance for archaic materials.
§ 8-803 — Nonstructural archaic materials and life-safety mitigation.
§ 8-805.1 — Existing solid masonry allowable shear (9 psi) conditions.
§ 8-806.7 — Existing adobe shear value (12 psi) and related adobe provisions.
§ 8-807.1 — Existing wood diaphragm/wall shear values and survey requirements.
§ 8-706.3 — Load-path verification (relevant when documenting load paths during the survey).

If you want, I can:

Draft a one-page survey checklist template aligned to the CHBC items above, or
Convert the “Worked example” into a sample stamped report excerpt that would meet typical enforcing-agency expectations.

Code references

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

CHBC § 8-801 High 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 § 8-804 High relevance — show source text
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. Higher-quality mortar may provide a greater shear value and shall be tested in accordance with Appendix A, Chapter A1 of the California Existing Building Code (CEBC) 2010 edition, and as modified by the CHBC.

8-805.2 Stone masonry.

8-805.2.1 Solid-backed stone masonry. Stone masonry solidly backed with brick masonry shall be treated as solid brick masonry as described in Section 8-805.1 and in the 2009 International Existing Building Code [®] (IEBC [®] ), provided representative testing and inspection verifies solid collar joints between stone and brick and that a reasonable number of stones lap with the brick wythes as headers or that steel anchors are present. Solid stone masonry where the wythes of stone effectively overlap to provide the equivalent header courses may also be treated as solid brick masonry.

8-805.2.2 Independent wythe stone masonry. Stone masonry with independent face wythes may be treated as solid brick masonry as described in Section 8-805.1 and the CEBC, provided representative testing and inspection verify that the core is essentially solid in the masonry wall and that steel ties are epoxied in drilled holes between outer stone wythes at floors, roof and not to exceed 4 feet (1219 mm) on center in each direction, between floors and roof. A reinforcing element shall exist or be provided at or near the top of all stone masonry walls.

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ARCHAIC MATERIALS AND METHODS OF CONSTRUCTION

8-805.2.3 Testing of stone masonry. Testing of stone masonry shall be similar to the 2010 CEBC requirements for brick masonry, except that representative stones which are not interlocked shall be pulled outward from the wall and shear area appropriately calculated after the test.
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 § 8-8 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 § 8-6 High relevance — show source text
CHAPTER 8-6 ACCESSIBILITY . . . . . . . . . . . . . . . . . . . . . . . . 11

Section

8-601 Purpose, Intent and Scope . . . . . . . . . . . . . . . . . . . . . . 11

8-602 Basic Provisions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

8-603 Alternatives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

8-604 Equivalent Facilitation. . . . . . . . . . . . . . . . . . . . . . . . . . 12

CHAPTER 8-7 STRUCTURAL REGULATIONS. . . . . . . . . . . . . 13

Section

8-701 Purpose, Intent and Scope . . . . . . . . . . . . . . . . . . . . . . 13 8-702 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

8-703 Structural Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 8-704 Nonhistorical Additions and

Nonhistorical Alterations . . . . . . . . . . . . . . . . . . . . . . . 13

8-705 Structural Regulations . . . . . . . . . . . . . . . . . . . . . . . . . . 13 8-706 Lateral Load Regulations. . . . . . . . . . . . . . . . . . . . . . . . 14

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
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.

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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 § 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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SECTION 8-809 — STEEL AND IRON
CHBC § 1.1 High relevance — show source text
It has been assumed that the building materials and their fastening, joining and incorporation into the building structure are sound mechanically. Therefore, some determination must be made that the original manufacture, the original construction practice and the rigors of aging and use have not weakened the building. This assessment can often be difficult because process and quality control was not good in many industries, and variations among locally available raw materials and manufacturing techniques often resulted in a product which varied widely in its strength and durability. The properties of iron and steel, for example, varied widely, depending on the mill and the process used.

There is nothing inherently inferior about archaic materials or construction techniques. The pressures that promote fundamental change are most often economic or technological matters not necessarily related to concerns for safety. The high cost of labor made wood lath and plaster uneconomical. The high cost of land and the congestion of the cities provided the impetus for high-rise construction. Improved technology made it possible. The difficulty with archaic materials is not a question of suitability, but familiarity.

Code requirements for the fire performance of key building elements (e.g., walls, floor/ceiling assemblies, doors, shaft enclosures) are stated in performance terms: hours of fire resistance. It matters not whether these elements were built in 1908 or 1980, only that they provide the required degree of fire resistance. The level of performance will be defined by the local community, primarily through the enactment of a building or rehabilitation code. This guideline is only a tool to help evaluate the various building elements, regardless of what the level of performance is required to be.

The problem with archaic materials is simply that documentation of their fire performance is not readily available. The application of engineering judgment is more difficult because building officials may not be familiar with the materials or construction method involved. As a result, either a full-scale fire test is required or the archaic construction in question removed and replaced. Both alternatives are time consuming and wasteful.

This guideline and the accompanying appendix are designed to help fill this information void. By providing the necessary documentation, there will be a firm basis for the continued acceptance of archaic materials and assemblies.

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RESOURCE A—GUIDELINES ON FIRE RATINGS OF ARCHAIC MATERIALS AND ASSEMBLIES

1—FIRE-RELATED PERFORMANCE OF ARCHAIC MATERIALS AND ASSEMBLIES

1.1 FIRE PERFORMANCE MEASURES

This guideline does not specify the level of performance required for the various building components. These requirements are controlled by the building occupancy and use and are set forth in the local building or rehabilitation code.

The fire resistance of a given building element is established by subjecting a sample of the assembly to a “standard” fire test which follows a “standard” time-temperature curve. This test method has changed little since the 1920s. The test results tabulated in the Appendix have been adjusted to reflect current test methods.

The current model building codes cite other fire-related properties not always tested for in earlier years: flame spread, smoke production and degree of combustibility. However, they can generally be assumed to fall within well-defined values because the principal combustible component of archaic materials is cellulose. Smoke production is more important today because of the increased use of plastics. However, the early flame spread tests, developed in the early 1940s, also included a test for smoke production.
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.

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8-8 ARCHAIC MATERIALS AND METHODS OF CONSTRUCTION

SECTION 8-801 — PURPOSE, INTENT AND SCOPE
CHBC § 4.00 High relevance — show source text
10
wood screw|1|24|4.00|0.90|DR|DR|2.85|DR|DR|DR| |Minimum 1x
Wood Furringd|Minimum 2x
Wood Stud|1/4" lag screw|11/2|12|4.00|2.65|1.50|0.90|4.00|1.65|0.80|DR| |Minimum 1x
Wood Furringd|Minimum 2x
Wood Stud|1/4" lag screw|11/2|16|4.00|1.95|0.95|0.50|4.00|1.10|DR|DR| |Minimum 1x
Wood Furringd|Minimum 2x
Wood Stud|1/4" lag screw|11/2|24|4.00|1.10|DR|DR|3.25|0.50|DR|DR| |For SI: 1 inch = 25.4 mm, 1 pound per square foot (psf) = 0.0479 kPa, 1 pound per square inch = 0.00689 MPa.
DR = Design Required, o.c. = on center.
a. Wood framing and furring shall be spruce-pine-fir or any wood species with a specific gravity of 0.42 or greater in accordance with ANSI/AWC NDS.
b. Nail fasteners shall comply with ASTM F1667, except nail length shall be permitted to exceed ASTM F1667 standard lengths.
c. The thickness of wood structural panels complying with the specific gravity requirements of Note a shall be permitted to be included in satisfying the minimum required
penetration into framing.
d. Where the required cladding fastener penetration into wood material exceeds3/4 inch and is not more than 11/2 inches, a minimum 2-inch nominal wood furring or an
approved design shall be used.
e. Foam sheathing shall have a minimum compressive strength of 15 psi in accordance with ASTM C578 or ASTM C1289.
f. Furring shall be spaced not greater than 24 inches on center in a vertical or horizontal orientation. In a vertical orientation, furring shall be located over wall studs and attached with
the required fastener spacing. In a horizontal orientation, the indicated 8-inch and 12-inch fastener spacing in furring shall be achieved by use of two fasteners into studs at 16 inches
and 24 inches on center, respectively.|For SI: 1 inch = 25.4 mm, 1 pound per square foot (psf) = 0.0479 kPa, 1 pound per square inch = 0.00689 MPa.
DR = Design Required, o.c. = on center.
a. Wood framing and furring shall be spruce-pine-fir or any wood species with a specific gravity of 0.42 or greater in accordance with ANSI/AWC NDS.
b. Nail fasteners shall comply with ASTM F1667, except nail length shall be permitted to exceed ASTM F1667 standard lengths.
c. The thickness of wood structural panels complying with the specific gravity requirements of Note a shall be permitted to be included in satisfying the minimum required
penetration into framing.
d. Where the required cladding fastener penetration into wood material exceeds3/4 inch and is not more than 11/2 inches, a minimum 2-inch nominal wood furring or an
approved design shall be used.
e.
CHBC § 14.5939 Medium relevance — show source text
4 mm, 1 pound per foot = 14.5939 N/m.
a. Plasters shall conform to Sections BJ104.4.3 through BJ104.4.9, BJ106.7 and BJ106.10.
b. Any metal mesh allowed by this appendix and installed in accordance with Section BJ106.9.
c. In accordance with Section BJ106.9.2, except as required to transfer roof loads to the plaster skins in accordance with Section BJ106.11.
d. For walls with a different plaster on each side, the lower value shall be used. For walls with plaster on only one side, half of the tabular value shall be used.
e. Shall use hydraulic or natural hydraulic lime.|For SI: 1 inch = 25.4 mm, 1 pound per foot = 14.5939 N/m.
a. Plasters shall conform to Sections BJ104.4.3 through BJ104.4.9, BJ106.7 and BJ106.10.
b. Any metal mesh allowed by this appendix and installed in accordance with Section BJ106.9.
c. In accordance with Section BJ106.9.2, except as required to transfer roof loads to the plaster skins in accordance with Section BJ106.11.
d. For walls with a different plaster on each side, the lower value shall be used. For walls with plaster on only one side, half of the tabular value shall be used.
e. Shall use hydraulic or natural hydraulic lime.|For SI: 1 inch = 25.4 mm, 1 pound per foot = 14.5939 N/m.
a. Plasters shall conform to Sections BJ104.4.3 through BJ104.4.9, BJ106.7 and BJ106.10.
b. Any metal mesh allowed by this appendix and installed in accordance with Section BJ106.9.
c. In accordance with Section BJ106.9.2, except as required to transfer roof loads to the plaster skins in accordance with Section BJ106.11.
d. For walls with a different plaster on each side, the lower value shall be used. For walls with plaster on only one side, half of the tabular value shall be used.
e. Shall use hydraulic or natural hydraulic lime.|For SI: 1 inch = 25.4 mm, 1 pound per foot = 14.5939 N/m.
a. Plasters shall conform to Sections BJ104.4.3 through BJ104.4.9, BJ106.7 and BJ106.10.
b. Any metal mesh allowed by this appendix and installed in accordance with Section BJ106.9.
c. In accordance with Section BJ106.9.2, except as required to transfer roof loads to the plaster skins in accordance with Section BJ106.11.
d. For walls with a different plaster on each side, the lower value shall be used. For walls with plaster on only one side, half of the tabular value shall be used.
e. Shall use hydraulic or natural hydraulic lime.|For SI: 1 inch = 25.4 mm, 1 pound per foot = 14.5939 N/m.
a. Plasters shall conform to Sections BJ104.4.3 through BJ104.4.9, BJ106.7 and BJ106.10.
b. Any metal mesh allowed by this appendix and installed in accordance with Section BJ106.9.
c. In accordance with Section BJ106.9.2, except as required to transfer roof loads to the plaster skins in accordance with Section BJ106.11.
d.
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

Frequently asked questions

Who must sign/stamp the survey report?

An architect or engineer knowledgeable in historical structures must prepare and sign/stamp the structural survey report as required by § 8-703.1.

Is material testing always required before assigning allowable stresses?

No — testing is required “when applicable.” The architect/engineer may assign values based on similarity to codified materials or tests; assigned values cannot exceed CHBC-prescribed limits without adequate testing and agency concurrence (§ 8-802, § 8-804).

What specific items must the survey document for vaults/veneers?

The survey must document anchorage, reinforcement, and any deterioration affecting seismic lateral resistance or falling hazards; CHBC calls out veneers/anchors specifically in Chapter 8-8 and related veneer sections (see § 8-804 and § 8-811.1).

Can historical records substitute for a physical survey?

Historical records may be used as part of the evaluation, but the CHBC still requires a physical survey by the qualified A/E and documentation of current condition for establishing allowable stresses (§ 8-703.3).

If the survey finds life-safety hazards, what then?

Nonconforming or unsafe conditions in the lateral-load-resisting system must be corrected or alternate resistance provided; nonstructural hazards must be mitigated, sometimes by strengthening or protective systems, per the CHBC structural chapters. See § 8-705.2.1 and Chapter 8-8 guidance.

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Related in the CHBC

What is the CHBC purpose, intent and scope for archaic materials?

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California Historical Building Code