CEBC · California Existing Building Code

Where are the Guidelines on Fire Ratings of Archaic Materials and Assemblies (Resource A)?

Resource A in the California Existing Building Code is an informational guideline (not a mandatory code section) that provides tables, histograms, and methods to estimate fire‑resistance for archaic materials and assemblies; use it to compare the existing assembly’s recommended hours to the project’s required rating or to justify testing/theoretical evaluation when no table match exists.

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Last reviewed: July 6, 2026

What the code requires — 2–4 sentences

The CEBC includes Resource A — “Guidelines on Fire Ratings of Archaic Materials and Assemblies” as an informational guideline to help evaluate the fire resistance, flame spread, smoke production, and combustibility of older (generally prior to 1950) construction. Resource A is a guidance document — not a prescriptive code section adopted verbatim — and is intended to be used to estimate fire performance and support upgrade decisions during repair, alteration, or rehabilitation projects. See Resource A (Guidelines on Fire Ratings of Archaic Materials and Assemblies) in the CEBC for the full guidance .

The single most important rule: Use Resource A to estimate an existing element’s fire performance (via the Appendix tables, histograms, Harmathy’s Rules, or testing). If the estimated performance meets or exceeds the project’s required rating, the element may remain; otherwise you must upgrade or use other accepted compensating measures .

Requirements in detail

Scope and purpose

Resource A is a guideline included in the CEBC to aid architects, engineers and code officials in assigning or estimating fire-resistance and related fire-performance values to archaic materials and assemblies (construction generally built before 1950) when modern test data are unavailable .
It is explicitly described as a tool (based on NIBS guidance) and is not formatted as mandatory code language; it is intended to support the local code official’s evaluation and decision-making process .

How to determine a fire-resistance rating (decision steps)

Identify the building element (wall, column, floor/ceiling assembly, beam, door). Resource A organizes its Appendix by element type (Section I–V) and then by construction type and minimum dimension/thickness .
Measure the decision‑relevant dimension(s) (for example, thickness, area of solid material, encasement depth) and identify the construction details (materials, facings, reinforcement).
Locate the matching table or histogram entry in Resource A Appendix and read the recommended fire‑resistance hours (REC. HOURS) and any Notes/Failure‑modes that apply .
If the assembly is not listed, use one of the accepted approaches in Resource A:
- Experimental approach: full‑scale or reduced test(s) with documented specimen procurement and witnessed testing .
- Theoretical approach: apply Harmathy’s Ten Rules and established heat‑flow / structural analysis methods, using the Appendix tables as data where appropriate .
Compare the estimated (or tested) rating to the project’s required fire resistance (as required by local code or the CEBC rehabilitation path). If the existing performance is less than required, select an upgrading method (repair/replace, add protection, or use compensating measures such as sprinklers) and re‑evaluate .

Decision‑relevant dimensions / quick reference table

Decision dimension	Typical values / thresholds	What it changes	Code Reference
Element type	Walls, Columns, Floor/Ceiling, Beams, Doors	Determines which Appendix section to use (I–V)	Resource A Appendix (Sections I–V)
Minimum thickness or dimension	e.g., 4 in., 6 in., 10 in., 12 in. — tables are grouped by these ranges	Selects the specific table/histogram row (different thickness ranges produce different REC. HOURS)	See tables (e.g., Masonry 4"–6", 6"–8", 10"–12") in Resource A Appendix
Construction detail	masonry type, hollow vs. solid units, brick facings, encasement material, plaster thickness	Alters the recommended hours and failure mode entries in the table	See table notes and item codes in Appendix tables (e.g., W‑12‑M‑23 etc.)
Required fire‑resistance for project	Determined by local CEBC rehab/repair/alteration requirements	Sets the target rating to compare against the estimated value	Project code requirement (local application of CEBC) — see CEBC chapters for compliance method references
Test vs. theory	Experimental (lab test) or theoretical (Harmathy rules)	Experimental gives direct evidence; theoretical relies on accepted calculation/methods	Resource A §3.1 (experimental) and §3.2 (theoretical)

Notes:

Each table row in the Appendix includes an Item Code, construction details, performance (load/time), notes, and a REC. HOURS value (recommended rating) — use the row that best matches the actual assembly .
Resource A tables include failure‑mode notes (collapse, flame‑through, hose stream performance) — read the notes for limitations and applicability .

Exceptions & special cases

Resource A is a guidance document and may not contain an exact match for every existing or unusual archaic assembly. If a specific assembly is not listed, Resource A explicitly directs users to either perform testing (experimental approach) or apply theoretical methods (Harmathy’s rules and calculations) .
Resource A tables assume the material and fastening are mechanically sound and representative of original construction. If age, corrosion, or degradation has significantly altered the material properties, Resource A emphasizes the need for further evaluation or testing before accepting the table value .
Some tables include entries marked by historical test standards (pre‑BMS‑92, BMS‑92, post‑BMS‑92) and notes on hose‑stream or reload performance; these historical distinctions may affect whether a rating is acceptable for current code enforcement — read the table notes carefully .

Common mistakes

Treating Resource A as mandatory prescriptive code instead of as a guideline — Resource A is guidance, not an enforceable “section” of the CEBC; local officials decide how to use it .
Using the wrong table because the wall/beam/column was mis‑classified (e.g., treating a cavity masonry as solid) — always verify construction details and minimum dimensions before selecting a table row .
Ignoring table Notes and failure‑mode remarks. Notes often control when the REC. HOURS value applies (e.g., only if plaster of a certain thickness is present) .
Assuming a tabulated REC. HOURS applies despite documented material deterioration — Resource A presumes sound mechanical condition; deterioration requires testing or conservative engineering judgment .
Skipping involvement of the AHJ (authority having jurisdiction) during test planning or when using nonstandard/small‑scale tests — Resource A advises local officials be involved in the testing process .

Worked example — concrete scenario with numbers

Scenario: You are rehabilitating a 1915 brick interior bearing wall that measures 12 in. total thickness (8 in. hollow structural tile core + 4 in. brick facing on one side). The local rehabilitation path requires 3‑hour fire resistance for this wall.

Identify element and measurement: interior bearing masonry wall, 12 in. thick (core + facing) — go to Section I (Walls) in Resource A Appendix and find the 10"–12" / 12" groups that describe clay tile cores with brick facings .
Locate matching table row: Resource A contains entries for 12" masonry assemblies with core and facing descriptions. For example, some 12" clay‑tile cores with 4" brick facings show REC. HOURS = 10 or 11 for heavy constructions, while other 12" cored concrete masonry may show REC. HOURS = 2 depending on the core and fill details — so the exact construction detail matters (unit solidity, fill, plaster, etc.) .
Compare: If your wall matches an entry with REC. HOURS ≥ 3, then Resource A indicates the existing wall meets the required 3‑hour rating and may remain. If the closest matching entry shows REC. HOURS < 3 (for example, a cored concrete masonry entry showing 2 hours), you must either upgrade the wall (add protection, plaster, or replace), or consider compensating measures like sprinklers and obtain AHJ approval .
If the wall is not an exact match (e.g., unusual hollow‑unit percentage or unknown fill), the guideline instructs either: (a) perform full‑scale or small‑scale testing representative of the assembly (witnessed and documented), or (b) apply Harmathy’s rules and heat‑flow/structural calculations to establish a defensible rating; involve the AHJ in the chosen approach .

Key point: Resource A contains specific numeric REC. HOURS entries for many 12" masonry variants — you must pick the row that matches your actual construction details and use the REC. HOURS for the comparison .

Related provisions

(The CEBC locates Resource A as an informational resource and cross‑references it in the Table of Contents and appendices. The CEBC chapters that commonly interact with Resource A are listed below. Resource A itself is published as a guideline in the CEBC Appendix/Resource section — it does not appear as a traditional numbered “§” code provision in the retrieved material; therefore no § numbers for Resource A are available in the retrieved files. See the file references below for the CEBC locations.)

Chapter 1 — Administration (context for applicability and AHJ authority)
Chapter 2 — Definitions (useful for defined terms like “existing building” and other code language)
Chapter 3 — Provisions for all compliance methods (determines how Resource A is used within the chosen compliance path)
Chapter 4 — Repairs (when repairs use original materials or must meet code upgrades; Resource A is referenced for evaluating existing assemblies)
Chapter 16 — Referenced Standards (shows which standards are enforceable as referenced; Resource A references testing standards and historical test protocols)
Appendix A–E and Resource A — Appendix A (seismic retrofit), Appendix C (wind retrofit), Appendix E (temporary uses), and Resource A (the fire‑ratings guideline itself) — see CEBC’s Table of Contents for placement of Resource A in the CEBC materials list .

If you need an exact CEBC “§” reference number for a mandatory requirement (for example, the code-mandated required fire resistance for a particular rehabilitation method), that requirement is in the code chapters listed above. Resource A itself is a guideline and the retrieved CEBC files do not provide a § number for Resource A; consult the AHJ or the CEBC printed book’s Table of Contents/Index for precise page or resource references .

Code references

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

CEBC § 1.11. High relevance — show source text
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.

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RESOURCE A-2 2025 CALIFORNIA EXISTING BUILDING CODE

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A GUIDELINES ON FIRE RATINGS OF ARCHAIC MATERIALS AND

ASSEMBLIES

User note:

About this resource: In the process of repair and alteration of existing buildings, based on the nature and the extent of the work, this code might require certain upgrades in the fire-resistance rating of building elements, at which time it becomes critical for the designers and the code officials to be able to determine the fire-resistance rating of the existing building elements as part of the overall evaluation for the assessment of the need for improvements. This resource document provides a guideline for such an evaluation for fire-resistance rating of archaic materials that is not typically found in the modern model building codes.

INTRODUCTION

The International Existing Building Code ® (IEBC®) is a comprehensive code with the goal of addressing all aspects of work taking place in existing buildings and providing user-friendly methods and tools for regulation and improvement of such buildings. This resource document is included within the cover of the IEBC with that goal in mind and as a step towards accomplishing that goal.

In the process of repair and alteration of existing buildings, based on the nature and the extent of the work, the IEBC might require certain upgrades in the fire-resistance rating of building elements, at which time it becomes critical for the designers and the code officials to be able to determine the fire-resistance rating of the existing building elements as part of the overall evaluation for the assessment of the need for improvements. This resource document provides a guideline for such an evaluation for fire-resistance ratings of archaic materials that are not typically found in the modern model building codes.

Resource A is only a guideline and is not intended to be a document for specific adoption as it is not written in the format or language of ICC’s International Codes and is not subject to the code development process.

PURPOSE

The Guidelines on Fire Ratings of Archaic Materials and Assemblies focuses upon the fire-related performance of archaic construction. “Archaic” encompasses construction typical of an earlier time, generally prior to 1950. “Fire-related performance” includes fire resistance, flame spread, smoke production and degree of combustibility.

The purpose of this guideline is to update the information which was available at the time of original construction, for use by architects, engineers and code officials when evaluating the fire safety of a rehabilitation project. In addition, information relevant to the evaluation of general classes of materials and types of construction is presented for those cases when documentation of the fire performance of a particular archaic material or assembly cannot be found.
CBC § 1950 High relevance — show source text
The International Existing Building Code ® (IEBC®) is a comprehensive code with the goal of addressing all aspects of work taking place in existing buildings and providing user-friendly methods and tools for regulation and improvement of such buildings. This resource document is included within the cover of the IEBC with that goal in mind and as a step towards accomplishing that goal.

In the process of repair and alteration of existing buildings, based on the nature and the extent of the work, the IEBC might require certain upgrades in the fire-resistance rating of building elements, at which time it becomes critical for the designers and the code officials to be able to determine the fire-resistance rating of the existing building elements as part of the overall evaluation for the assessment of the need for improvements. This resource document provides a guideline for such an evaluation for fire-resistance ratings of archaic materials that are not typically found in the modern model building codes.

Resource A is only a guideline and is not intended to be a document for specific adoption as it is not written in the format or language of ICC’s International Codes and is not subject to the code development process.

PURPOSE

The Guidelines on Fire Ratings of Archaic Materials and Assemblies focuses upon the fire-related performance of archaic construction. “Archaic” encompasses construction typical of an earlier time, generally prior to 1950. “Fire-related performance” includes fire resistance, flame spread, smoke production and degree of combustibility.

The purpose of this guideline is to update the information which was available at the time of original construction, for use by architects, engineers and code officials when evaluating the fire safety of a rehabilitation project. In addition, information relevant to the evaluation of general classes of materials and types of construction is presented for those cases when documentation of the fire performance of a particular archaic material or assembly cannot be found.

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.
CBC § 107 High relevance — show source text
E108 Referenced Standards . . . . . . . . . . . . . . . . APPENDIX E-5

RESOURCE A GUIDELINES ON FIRE RATINGS OF

ARCHAIC MATERIALS AND ASSEMBLIES. . . . RESOURCE A-3

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .RESOURCE A-3

Purpose. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .RESOURCE A-3

1—Fire-Related Performance of Archaic Materials and

Assemblies . . . . . . . . . . . . . . . . . . . . . . . .RESOURCE A-4

2—Building Evaluation . . . . . . . . . . . . . . . . . . . . . .RESOURCE A-5

3—Final Evaluation and Design Solution . . . . . .RESOURCE A-8

4—Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RESOURCE A-14

APPENDIX. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RESOURCE A-17

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RESOURCE A-17

Table of Contents. . . . . . . . . . . . . . . . . . . . . . . . . RESOURCE A-17

Purpose and Procedure . . . . . . . . . . . . . . . . . . . RESOURCE A-19

Section I—Walls . . . . . . . . . . . . . . . . . . . . . . . . . . RESOURCE A-20

Section II—Columns. . . . . . . . . . . . . . . . . . . . . . . RESOURCE A-67

Section III—Floor/Ceiling Assemblies . . . . . . . RESOURCE A-91

Section IV—Beams . . . . . . . . . . . . . . . . . . . . . . . RESOURCE A-107

Section V—Doors . . . . . . . . . . . . . . . . . . . . . . . . RESOURCE A-112

Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . RESOURCE A-115

INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . INDEX-1

HISTORY NOTE APPENDIX . . . . . . . . . . . . . . . . . . . . . . . . HIST-1

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CALIFORNIA EXISTING BUILDING CODE – MATRIX ADOPTION TABLE

CHAPTER 1 – ADMINISTRATION

(Matrix Adoption Tables are nonregulatory, intended only as an aid to the code user. See Chapter 1 for state agency authority and building applications.)

|Adopting
California Existing Building Code High relevance — show source text
C301 Referenced Standards . . . . . . . . . . . . . . . APPENDIX C-31

APPENDIX D BOARD OF APPEALS . . . . . . . . . . . APPENDIX D-3

D101 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . APPENDIX D-3

APPENDIX E TEMPORARY EMERGENCY

USES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . APPENDIX E-3

E101 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . APPENDIX E-3

E102 Definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . APPENDIX E-3

E103 Submittal Documents . . . . . . . . . . . . . . . . APPENDIX E-3

E104 Conformance . . . . . . . . . . . . . . . . . . . . . . . . APPENDIX E-3

E105 Permits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . APPENDIX E-3

E106 General Standards for

Emergency Uses. . . . . . . . . . . . . . . . . . . . APPENDIX E-3

E107 Use of Specific Standards . . . . . . . . . . . . . APPENDIX E-4

E108 Referenced Standards . . . . . . . . . . . . . . . . APPENDIX E-5

RESOURCE A GUIDELINES ON FIRE RATINGS OF

ARCHAIC MATERIALS AND ASSEMBLIES. . . . RESOURCE A-3

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .RESOURCE A-3

Purpose. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .RESOURCE A-3

1—Fire-Related Performance of Archaic Materials and

Assemblies . . . . . . . . . . . . . . . . . . . . . . . .RESOURCE A-4

2—Building Evaluation . . . . . . . . . . . . . . . . . . . . . .RESOURCE A-5

3—Final Evaluation and Design Solution . . . . . .RESOURCE A-8

4—Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RESOURCE A-14

APPENDIX. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RESOURCE A-17

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RESOURCE A-17

Table of Contents. . . . . . . . . . . . . . . . . . . . . . . . . RESOURCE A-17
CEBC § 4.3 High relevance — show source text
The “thickness design” concept is essentially a special case of Harmathy’s Rules (specifically Rules 1 and 2). It should be recognized that the only source of data is the Appendix tables. If other data are used, it must be in connection with the approach below.

4.3 The fire resistance of building elements can be established by applying Harmathy’s Ten Rules of Fire Resistance Ratings as set forth in Section 3.2 of the guideline. This is subject to the following limitations:

The data from the tables can be utilized subject to the limitations in Section 4.2.

Test reports from recognized journals or published papers can be used to support data utilized in applying Harmathy’s Rules.

Calculations utilizing recognized and well established computational techniques can be used in applying Harmathy’s Rules. These include, but are not limited to, analysis of heat flow, mechanical properties, deflections and load bearing capacity.

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RESOURCE A-16 2025 CALIFORNIA EXISTING BUILDING CODE

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APPENDIX

INTRODUCTION

The fire-resistance tables that follow are a part of Resource A and provide a tabular form of assigning fire-resistance ratings to various archaic building elements and assemblies.

These tables for archaic materials and assemblies do for archaic materials what Tables 721.1(1) through 721.1(3) of the California Building Code [®] do for more modern building elements and assemblies. The fire-resistance tables of Resource A should be used as described in the “Purpose and Procedure” that follows the table of contents for these tables.

TABLE OF CONTENTS

Purpose and Procedure RESOURCE A-19

Section I—Walls

1.1.1 Masonry 0 in. to less than 4 in. thick RESOURCE A-20

1.1.2 Masonry 4 in. to less than 6 in. thick RESOURCE A-23

1.1.3 Masonry 6 in. to less than 8 in. thick RESOURCE A-29

1.1.4 Masonry 8 in. to less than 10 in. thick RESOURCE A-33

1.1.5 Masonry 10 in. to less than 12 in. thick RESOURCE A-40

1.1.6 Masonry 12 in. to less than 14 in. thick RESOURCE A-43

1.1.7 Masonry 14 in. or more thick RESOURCE A-48

1.2.1 Metal Frame 0 in. to less than 4 in. thick RESOURCE A-51

1.2.2 Metal Frame 4 in. to less than 6 in. thick RESOURCE A-54

1.2.3 Metal Frame 6 in. to less than 8 in. thick RESOURCE A-55

1.2.4 Metal Frame 8 in. to less than 10 in. thick RESOURCE A-56

1.3.1 Wood Frame 0 in. to less than 4 in. thick RESOURCE A-56

1.3.2 Wood Frame 4 in. to less than 6 in. thick RESOURCE A-57

1.3.3 Wood Frame 6 in. to less than 8 in. thick RESOURCE A-63

1.4.1 Miscellaneous Materials 0 in. to less than 4 in. thick RESOURCE A-64

CEBC § 2.1 High relevance — show source text

horizontal exitway|b)
Enclosed horizontal exitway||||| |c)
Other|c)
Other|||||

The required fire resistance and flame spread for each building element are normally established by the local building or rehabilitation code. The fire performance of the existing materials and assemblies should then be estimated, using one of the techniques described below. If the fire performance of the existing building element(s) is equal to or greater than that required, the materials and assemblies may remain. If the fire performance is less than required, then corrective measures must be taken.

The most common methods of upgrading the level of protection are to either remove and replace the existing building element(s) or to repair and upgrade the existing materials and assemblies. Other fire protection measures, such as automatic sprinklers or detection and alarm systems, also could be considered, though they are beyond the scope of this guideline. If the upgraded protection is still less than that required or deemed to be acceptable, additional corrective measures must be taken. This process must continue until an acceptable level of performance is obtained. TABLE 2.1(2) PRELIMINARY EVALUATION WORKSHEET

BUILDING ELEMENT	Col2	REQUIRED FIRE RESISTANCE	REQUIRED FLAME SPREAD	ESTIMATED FIRE RESISTANCE	ESTIMATED FLAME SPREAD	METHOD OF UPGRADING	ESTIMATED UPGRADED PROTECTION	NOTES
Exterior Bearing Walls	Exterior Bearing Walls
Interior Bearing Walls	Interior Bearing Walls
Exterior Nonbearing Walls	Exterior Nonbearing Walls
Interior Nonbearing Walls or Partitions	A
Interior Nonbearing Walls or Partitions	B
Structural Frame: Columns	Structural Frame: Columns
Beams	Beams
Other	Other
Floor/Ceiling Structural System: Spanning	Floor/Ceiling Structural System: Spanning
Roofs	Roofs
Doors (including frame and hardware): a) Enclosed vertical exitway	Doors (including frame and hardware): a) Enclosed vertical exitway
b) Enclosed horizontal exitway	b) Enclosed horizontal exitway
c) Others	c) Others

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

2.2 FIRE RESISTANCE OF EXISTING BUILDING ELEMENTS

The fire resistance of the existing building elements can be estimated from the tables and histograms contained in the Appendix. The Appendix is organized first by type of building element: walls, columns, floor/ceiling assemblies, beams and doors. Within each building element, the tables are organized by type of construction (e.g., masonry, metal, wood frame) and then further divided by minimum dimensions or thickness of the building element.

CEBC § 2.5.2.2 High relevance — show source text

TABLE 2.5.2.2 STEEL COLUMNS—BRICK AND BLOCK ENCASEMENTS MINIMUM DIMENSION 12″ TO LESS THAN 14″	Col2	Col3	Col4	Col5	Col6	Col7	Col8	Col9	Col10
ITEM CODE	MINIMUM DIMENSION	CONSTRUCTION DETAILS	PERFORMANCE	PERFORMANCE	REFERENCE NUMBER	REFERENCE NUMBER	REFERENCE NUMBER	NOTES	REC. HOURS
ITEM CODE	MINIMUM DIMENSION	CONSTRUCTION DETAILS	LOAD	TIME	PRE-BMS-92	BMS-92	POST-BMS-92	POST-BMS-92	POST-BMS-92
C-12-SB-1	12″	12″ × 15″ brick encased steel columns; 8″ × 6″ × 35 lbs “H” beam; protection: 25/8″ thick brick; joints broken in alternate courses; cement-sand grout; fill of broken brick and mortar.	90 tons	1 hr 49 min			7	1	13/4

For SI: 1 inch = 25.4 mm, 1 pound = 0.004448 kN, 1 ton = 8.896 kN.

Notes:

Failure mode—collapse.

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

TABLE 2.5.2.3 STEEL COLUMNS—BRICK AND BLOCK ENCASEMENTS MINIMUM DIMENSION 14″ TO LESS THAN 16″	Col2	Col3	Col4	Col5	Col6	Col7	Col8	Col9	Col10
ITEM CODE	MINIMUM DIMENSION	CONSTRUCTION DETAILS	PERFORMANCE	PERFORMANCE	REFERENCE NUMBER	REFERENCE NUMBER	REFERENCE NUMBER	NOTES	REC. HOURS
ITEM CODE	MINIMUM DIMENSION	CONSTRUCTION DETAILS	LOAD	TIME	PRE-BMS-92	BMS-92	POST-BMS-92	POST-BMS-92	POST-BMS-92
C-15-SB-1	15″	15″ × 17″ brick encased steel columns; 8″ × 6″ × 35 lbs “H” beam; protection: 41/2″ thick brick; joints broken in alternate courses; cement-sand grout; fill of broken brick and mortar.	45 tons	6 hrs			7	1	6
C-15-SB-2	15″	15″ × 17″ brick encased steel columns;

CEBC § 1.1.2 High relevance — show source text
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RESOURCE A—GUIDELINES ON FIRE RATINGS OF ARCHAIC MATERIALS AND ASSEMBLIES

TABLE 1.1.2—continued

MASONRY WALLS 4 ″ TO LESS THAN 6 ″ THICK
1. See appendix for construction and design details for clay tile walls.
2. Failure mode—flame thru or crack formation showing flames.
3. Hole formed at 25 minutes; partition collapsed at 42 minutes on removal from furnace.
4. Failure mode—collapse.
5. Hose stream pass.
6. Hose stream hole formed in specimen.
7. Load: 80 psi for gross wall cross-sectional area.
8. One cell in wall thickness.
9. Two cells in wall thickness.
10. Double cells plus one cell in wall thickness.
11. One cell in wall thickness, cells filled with broken tile, crushed stone, slag, cinders or sand mixed with mortar.
12. Dense hard-burned clay or shale tile.
13. Medium-burned clay tile.
14. Not less than [5] / 8 inch thickness of 1:3 sanded gypsum plaster.
15. Units of not less than 30 percent solid material.
16. Units of not less than 40 percent solid material.
17. Units of not less than 50 percent solid material.
18. Units of not less than 45 percent solid material.
19. Units of not less than 60 percent solid material.
20. All tiles laid in Portland cement-lime mortar.
21. Minimum [1] / 2 inch—1:3 sanded gypsum plaster.
22. Laid in 1:3 sanded gypsum mortar. Voids in hollow units not to exceed 30 percent.
23. Units of expanded slag or pumice aggregate.
24. Units of crushed limestone, blast furnace slag, cinders and expanded clay or shale.
25. Units of calcareous sand and gravel. Coarse aggregate, 60 percent or more calcite and dolomite.
26. Units of siliceous sand and gravel. Ninety percent or more quartz, chert or flint.
27. Unit at least 49 percent solid.
28. Unit at least 62 percent solid.
29. Unit at least 65 percent solid.
30. Unit at least 73 percent solid.
31. Ratings based on one unit and one cell in wall thickness.
32. See clay tile partition design construction drawings below.
RESOURCE A-28 2025 CALIFORNIA EXISTING BUILDING CODE

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NUMBER OF ASSEMBLIES

10

5

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

FIGURE 1.1.3

MASONRY WALLS 6 ″ TO LESS THAN 8 ″ THICK

|Col1|66
65 64 The number in each box is
keyed to the last number in the
Item Code column in the table.
58 62
For example:
26 48 53 54 55 W-6-M-63
25 41 49 50 52
21 29 39 43 44 36
12 28 31 42 16 35 61 63
10 22 27 30 40 15

CEBC § 25.4 High relevance — show source text

For SI: 1 inch = 25.4 mm, 1 pound = 0.004448 kN, 1 ton = 8.896 kN.

Notes:

Passed 2-hour fire exposure test.
Collapsed during hose stream test.

2025 CALIFORNIA EXISTING BUILDING CODE RESOURCE A-89

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

TABLE 2.5.4.3 STEEL COLUMNS—MISCELLANEOUS ENCASEMENTS MINIMUM DIMENSION 10″ TO LESS THAN 12″	Col2	Col3	Col4	Col5	Col6	Col7	Col8	Col9	Col10
ITEM CODE	MINIMUM DIMENSION	CONSTRUCTION DETAILS	PERFORMANCE	PERFORMANCE	REFERENCE NUMBER	REFERENCE NUMBER	REFERENCE NUMBER	NOTES	REC. HOURS
ITEM CODE	MINIMUM DIMENSION	CONSTRUCTION DETAILS	LOAD	TIME	PRE-BMS-92	BMS-92	POST-BMS-92	POST-BMS-92	POST-BMS-92
C-11-SM-1	111/2″	111/2″ × 131/2″ wood, wool and plaster- protected steel columns; 8″ × 6″ × 35 lbs “H” beam; protection: wood-wool-cement paste as fill and to 2″ cover over beam;3/4″ gypsum plaster finish.	90 tons	2 hrs			7	1–3	2
C-10-SM-2	10″	10″ × 12″ asbestos-protected steel columns; 8″ × 6″ × 35 lbs “H” beam; protection: sprayed on asbestos paste to 2″ cover over column.	90 tons	4 hrs			7	2–4	4

For SI: 1 inch = 25.4 mm, 1 pound = 0.004448 kN, 1 ton = 8.896 kN.

Notes:

Passed 2-hour fire exposure (Grade “C,” British).
Passed hose stream test.
Passed reload test.
Passed 4-hour fire exposure test.

TABLE 2.5.4.4 STEEL COLUMNS—MISCELLANEOUS ENCASEMENTS MINIMUM DIMENSION 12″ TO LESS THAN 14″	Col2	Col3	Col4	Col5	Col6	Col7	Col8	Col9	Col10
ITEM CODE	MINIMUM DIMENSION	CONSTRUCTION DETAILS	PERFORMANCE	PERFORMANCE	REFERENCE NUMBER	REFERENCE NUMBER	REFERENCE NUMBER	NOTES	**REC.

CEBC § 2.5.4.2 High relevance — show source text

Failure mode—collapse.

TABLE 2.5.4.2 STEEL COLUMNS—MISCELLANEOUS ENCASEMENTS MINIMUM DIMENSION 8″ TO LESS THAN 10″	Col2	Col3	Col4	Col5	Col6	Col7	Col8	Col9	Col10
ITEM CODE	MINIMUM DIMENSION	CONSTRUCTION DETAILS	PERFORMANCE	PERFORMANCE	REFERENCE NUMBER	REFERENCE NUMBER	REFERENCE NUMBER	NOTES	REC. HOURS
ITEM CODE	MINIMUM DIMENSION	CONSTRUCTION DETAILS	LOAD	TIME	PRE-BMS-92	BMS-92	POST-BMS-92	POST-BMS-92	POST-BMS-92
C-9-SM-1	95/8″	95/8″ × 113/8″ asbestos slab and cement plaster- protected columns; 8″ × 6″ × 35 lbs “H” beam; protection: 1″ asbestos slab; wire wound;5/8″ plaster.	90 tons	2 hrs			7	1, 2	2

For SI: 1 inch = 25.4 mm, 1 pound = 0.004448 kN, 1 ton = 8.896 kN.

Notes:

Passed 2-hour fire exposure test.
Collapsed during hose stream test.

2025 CALIFORNIA EXISTING BUILDING CODE RESOURCE A-89

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

TABLE 2.5.4.3 STEEL COLUMNS—MISCELLANEOUS ENCASEMENTS MINIMUM DIMENSION 10″ TO LESS THAN 12″	Col2	Col3	Col4	Col5	Col6	Col7	Col8	Col9	Col10
ITEM CODE	MINIMUM DIMENSION	CONSTRUCTION DETAILS	PERFORMANCE	PERFORMANCE	REFERENCE NUMBER	REFERENCE NUMBER	REFERENCE NUMBER	NOTES	**REC.

California Existing Building Code High relevance — show source text
see
Notes 2, 6, 14, 18; no facings.|80 psi|2 hrs
30 min||1||1, 20|21/2| |W-12-M-15|12″|Core: clay or shale structural tile; see
Notes 2, 4, 13, 18; no facings.|80 psi|3 hrs
30 min||1||1, 20|31/2| |W-12-M-16|12″|Core: clay or shale structural tile; see
Notes 2, 4, 13, 19; no facings.|80 psi|3 hrs||1||1, 20|3| |W-12-M-17|12″|Core: clay or shale structural tile; see
Notes 3, 6, 9, 18; no facings.|80 psi|3 hrs
30 min||1||1, 20|31/2| |W-12-M-18|12″|Core: clay or shale structural tile; see
Notes 3, 6, 9, 19; no facings.|80 psi|2 hrs||1||1, 20|2| |W-12-M-19|12″|Core: clay or shale structural tile; see
Notes 3, 6, 14, 18; no facings.|80 psi|4 hrs||1||1, 20|4| |W-12-M-20|12″|Core: clay or shale structural tile; see
Notes 3, 6, 14, 19; no facings.|80 psi|2 hrs
30 min||1||1, 20|21/2| |W-12-M-21|12″|Core: clay or shale structural tile; see
Notes 3, 6, 16, 18; no facings.|80 psi|5 hrs||1||1, 20|5| |W-12-M-22|12″|Core: clay or shale structural tile; see
Notes 3, 6, 16, 19; no facings.|80 psi|3 hrs||1||1, 20|3| |W-12-M-23|12″|Core: 8″, 70% solid clay or shale struc-
tural tile; 4″ brick facings on one side.|80 psi|10 hrs||1||1, 20|10| |W-12-M-24|12″|Core: 8″, 70% solid clay or shale struc-
tural tile; 4″ brick facings on one side.|N/A|11 hrs||1||1|11| |W-12-M-25|12″|Core: 8″, 40% solid clay or shale struc-
tural tile; 4″ brick facings on one side.|80 psi|6 hrs||1||1, 20|6| |W-12-M-26|12″|Cored concrete masonry; see Notes 1, 9,
15, 16, 20; no facings.|80 psi|2 hrs||1||1, 20|2| |W-12-M-27|12″|Cored concrete masonry; see Notes 2,
18, 26, 34, 41; no facings.|80 psi|5 hrs||1||1,
CEBC § 1-3 High relevance — show source text
Appendix C Guidelines for the Wind Retrofit of Existing Buildings.

The purpose of Appendix C is to provide voluntary prescriptive alternatives for addressing the retrofit of buildings in high-wind areas. Currently, there are two chapters which deal with the retrofit of gable ends and the fastening of roof decks, Appendix Chapters C1 and C2, respectively. This appendix includes its own referenced standards.

Appendix D Board of Appeals.

Appendix D contains the provisions for appeal and the establishment of a board of appeals. The provisions include the application for an appeal, the makeup of the board of appeals and the conduct of the appeal process.

Appendix E Temporary Emergency Uses.

Appendix E is intended to provide guidance for designers, engineers, architects and fire and building officials on allowing temporary emergency uses of existing buildings with respect to the minimum code requirements. This appendix is a template or checklist that references the relevant code requirement of concerns.

Resource A Guidelines on Fire Ratings of Archaic Materials and Assemblies.

In the process of repair and alteration of existing buildings, based on the nature and the extent of the work, the CEBC might require certain upgrades in the fire-resistance rating of building elements, at which time it becomes critical for the designers and the code

xiv 2025 CALIFORNIA EXISTING BUILDING CODE

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officials to be able to determine the fire-resistance rating of the existing building elements as part of the overall evaluation for the assessment of the need for improvements. These guidelines are based upon the Guideline on Fire Ratings of Archaic Materials published by the National Institute of Building Sciences (NIBS).

2025 CALIFORNIA EXISTING BUILDING CODE xv

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xvi 2025 CALIFORNIA EXISTING BUILDING CODE

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CONTENTS

CHAPTER 1 ADMINISTRATION . . . . . . . . . . . . . . . . . . . . . . . 1-3

DIVISION I – CALIFORNIA ADMINISTRATION . . . . . . . . . . . . . . . . . . . 1-3

1.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

1.2 Building Standards Commission. . . . . . . . . . . . . . . . . . . 1-5

1.3 Board of State and Community Corrections. . . . . . . . . 1-7

1.4 Department of Consumer Affairs. . . . . . . . . . . . . . . . . . . 1-7

1.5 California Energy Commission. . . . . . . . . . . . . . . . . . . . . 1-7

1.6 Department of Food and Agriculture . . . . . . . . . . . . . . . 1-7

1.7 Department of Public Health . . . . . . . . . . . . . . . . . . . . . . 1-7

Frequently asked questions

What exactly is Resource A — mandatory code or guidance?

Resource A is guidance only — a CEBC Resource (Guideline on Fire Ratings of Archaic Materials and Assemblies). It is not written in mandatory code language for adoption; local officials use it to estimate fire performance and to support decisions .

If an assembly is not listed in Resource A, what should I do?

Use Resource A’s recommended paths: (1) perform experimental testing (full‑scale or small specimens with AHJ involvement) or (2) apply theoretical methods (Harmathy’s Rules and accepted calculations), using Appendix tables and peer‑reviewed data where possible .

Do Resource A table ratings apply if the element is degraded by age?

Not automatically. Resource A assumes materials and fastening are mechanically sound; if significant deterioration exists, the guideline recommends additional evaluation or testing before accepting the tabulated ratings .

Can I use Resource A instead of local code requirements?

No. Resource A provides a method to estimate an assembly’s fire performance. The governing required fire‑resistance (the target rating) is set by the applicable CEBC chapters and the AHJ. Use Resource A to see if the existing assembly meets that required rating; it does not replace mandatory requirements .

Where in the CEBC is Resource A located?

Resource A appears in the CEBC as Resource A — Guidelines on Fire Ratings of Archaic Materials and Assemblies in the Appendix/Resources section and is called out in the Table of Contents. The retrieved CEBC files show Resource A content and Appendix tables (Sections I–V) but do not supply a § number for Resource A itself — it is listed as Resource A in the CEBC materials list .

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Related in the CEBC

Where are referenced standards for temporary emergency uses listed?

Where are supplementary accessibility requirements for existing buildings?

How does Appendix D establish the Board of Appeals?

Appendices B, D, E and Resource A — accessibility, appeals, emergency uses and fire ratings

California Existing Building Code