CRC · California Residential Code
Chimneys and Fireplaces
Chapter 10 of the CRC governs masonry and factory‑built fireplaces and chimneys — prescribing construction, flue‑lining, clearances, listing/installation rules, and seismic anchorage.
Last reviewed: July 6, 2026
Overview
Chapter 10 of the California Residential Code covers the design, construction and installation requirements for masonry fireplaces and chimneys, masonry heaters, and factory‑built (listed) fireplaces and chimneys, and it includes provisions for seismic reinforcing and anchorage of masonrywork. See the chapter introduction for the scope and purpose of Chapter 10.
Key mandatory provisions you’ll use most often include the masonry‑fireplace rules in §R1001, masonry‑chimney requirements in §R1003, the factory‑built fireplace and chimney rules in §R1004 and §R1005, and exterior combustion‑air requirements in §R1006. These sections address footings and hearth construction, smoke‑chamber and flue‑lining requirements, clearances to combustibles, listing/labeling for factory units, and seismic anchorage.
The chapter mixes prescriptive masonry details (e.g., footings, hearth thickness, smoke‑chamber geometry and reinforcement) with a listing/labeling approach for factory‑built systems; for example, masonry chimneys must be lined and use materials appropriate for the connected appliance, while factory units must be installed per their listing and UL test standards. Consult the specific sections for dimensions, reinforcement and installation conditions before design or permitting.
In this section
Code references
Grounded in the retrieved California Residential Code — click a citation to read the verbatim passage:
CRC § 2025 High relevance — show source text
Chapter 9 Roof Assemblies.
Chapter 9 regulates the design and construction of roof assemblies. A roof assembly includes the roof deck, vapor retarder, substrate or thermal barrier, insulation, vapor retarder and roof covering. This chapter provides the requirement for wind resistance of roof coverings.
The types of roof covering materials and installation regulated by Chapter 9 are: asphalt shingles, clay and concrete tile, metal roof shingles, mineral-surfaced roll roofing, slate and slate-type shingles, wood shakes and shingles, built-up roofs, metal roof panels, modified bitumen roofing, thermoset and thermoplastic single-ply roofing, sprayed polyurethane foam roofing, liquid applied coatings and photovoltaic shingles. Chapter 9 also provides requirements for roof drainage, flashing, above deck thermal insulation, rooftop-mounted photovoltaic systems and recovering or replacing an existing roof covering.
Chapter 10 Chimneys and Fireplaces.
Chapter 10 contains requirements for the safe construction of masonry chimneys and fireplaces and establishes the standards for the use and installation of factory-built chimneys, fireplaces and masonry heaters. Chimneys and fireplaces constructed of masonry rely on prescriptive requirements for the details of their construction; the factory-built type relies on the listing and labeling method of approval. Chapter 10 provides the requirements for seismic reinforcing and anchorage of masonry fireplaces and chimneys.
Chapter 11 [RE] Energy Efficiency.
Chapter 11 is not adopted in California. See California Energy Code, Title 24, Part 6.
Chapter 12 Mechanical Administration.
Chapter 12 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
Chapter 13 General Mechanical System Requirements.
Chapter 13 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
Chapter 14 Heating and Cooling Equipment and Appliances.
Chapter 14 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
Chapter 15 Exhaust Systems.
Chapter 15 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
Chapter 16 Duct Systems.
Chapter 16 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
Chapter 17 Combustion Air.
Chapter 17 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
Chapter 18 Chimneys and Vents.
Chapter 18 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
Chapter 19 Special Appliances, Equipment and Systems.
Chapter 19 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
Chapter 20 Boilers and Water Heaters.
Chapter 20 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
xvi 2025 CALIFORNIA RESIDENTIAL CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
Chapter 21 Hydronic Piping.
Chapter 21 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
Chapter 22 Special Piping and Storage Systems.
Chapter 22 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
Chapter 23 Solar Thermal Energy Systems.
CRC § 25.4 High relevance — show source text
Not required in Seismic Design Category A or B.|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 square foot = 0.0929 m2.
Note: This table provides a summary of major requirements for the construction of masonry chimneys and fireplaces. Letter references are to Figure R1001.1, which shows
examples of typical construction. This table does not cover all requirements, nor does it cover all aspects of the indicated requirements. For the actual mandatory require-
ments of the code, see the indicated section of text.
a. The letters refer to Figure R1001.1.
b. Not required in Seismic Design Category A or B.|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 square foot = 0.0929 m2.
Note: This table provides a summary of major requirements for the construction of masonry chimneys and fireplaces. Letter references are to Figure R1001.1, which shows
examples of typical construction. This table does not cover all requirements, nor does it cover all aspects of the indicated requirements. For the actual mandatory require-
ments of the code, see the indicated section of text.
a. The letters refer to Figure R1001.1.
b. Not required in Seismic Design Category A or B.|2025 CALIFORNIA RESIDENTIAL CODE 10-3
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
CHIMNEYS AND FIREPLACES
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm.
FIGURE R1001.1—FIREPLACE AND CHIMNEY DETAILS
R1001.2 Footings and foundations. Footings for masonry fireplaces and their chimneys shall be constructed of concrete or solid masonry not less than 12 inches (305 mm) thick and shall extend not less than 6 inches (152 mm) beyond the face of the fireplace or foundation wall on all sides. Footings shall be founded on natural, undisturbed earth or engineered fill below frost depth. In areas not subjected to freezing, footings shall be not less than 12 inches (305 mm) below finished grade.
R1001.2.1 Ash dump cleanout. Cleanout openings located within foundation walls below fireboxes, where provided, shall be equipped with ferrous metal or masonry doors and frames constructed to remain tightly closed except when in use. Cleanouts shall be located to allow access so that ash removal will not create a hazard to combustible materials.
R1001.3 Seismic reinforcing. Masonry or concrete chimneys in all structures regulated by this code assigned to Seismic Design Category C, D 0, D 1 or D 2 shall be reinforced. Reinforcing shall conform to the requirements set forth in Table R1001.1 and Section R606.
R1001.3.1 Vertical reinforcing. For chimneys up to 40 inches (1016 mm) wide, four No. 4 continuous vertical bars shall be placed between wythes of solid masonry or within the cells of hollow unit masonry and grouted in accordance with Section R606. Grout
10-4 2025 CALIFORNIA RESIDENTIAL CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
CHIMNEYS AND FIREPLACES
CRC § 1001.11 High relevance — show source text
3||||X|||||||||||||||||||| |R1001.4||||X|||||||||||||||||||| |Table R1001.1, Footnote (b)||||X|||||||||||||||||||| |R1001.11|||X||||||||||||||||||||| |Figure 1001.11|||X||||||||||||||||||||| |R1001.12|||X||||||||||||||||||||| |R1003.3||||X|||||||||||||||||||| |R1003.4||||X|||||||||||||||||||| |R1003.9.1|||X||||||||||||||||||||| |R1003.9.2|||X||||||||||||||||||||| |R1003.11.3||||X|||||||||||||||||||| |R1003.14||||X|||||||||||||||||||| |R1003.18|||X||||||||||||||||||||| |Figure R1003.18|||X||||||||||||||||||||| |R1003.19|||X||||||||||||||||||||| |R1004.1.1||||X|||||||||||||||||||| |R1004.4||||†||||||||||||||||||||
The state agency does not adopt sections identified with the following symbol: †
2025 CALIFORNIA RESIDENTIAL CODE 10-1
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
10-2 2025 CALIFORNIA RESIDENTIAL CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
10 CHIMNEYS AND FIREPLACES
User notes:
About this chapter: Chapter 10 contains requirements for the construction, seismic reinforcing and anchorage of masonry chimneys and fireplaces; and establishes standards for the use and installation of factory-built chimneys, fireplaces and masonry heaters. Chimneys and fireplaces constructed of masonry rely on prescriptive requirements for the details of their construction; factory-built versions rely on the listing and labeling method of approval.
SECTION R1001—MASONRY FIREPLACES
R1001.1 General. Masonry fireplaces shall be constructed in accordance with this section and the applicable provisions of Chapters 3 and 4.
TABLE R1001.1—SUMMARY OF REQUIREMENTS FOR MASONRY FIREPLACES AND CHIMNEYS Col2 Col3 ** ITEM** ** LETTERa** ** REQUIREMENTS** Hearth slab thickness A 4 inches Hearth extension (each side of opening) B 8-inch fireplace opening < 6 square feet.
12-inch fireplace opening ≥ 6 square feet.Hearth extension (front of opening) C 16-inch fireplace opening < 6 square feet.
20-inch fireplace opening ≥ 6 square feet.Hearth slab reinforcing D Reinforced to carry its own weight and all imposed loads. Thickness of wall of firebox E 10-inch solid brick or 8 inches where a firebrick lining is used.
Joints in firebrick1/4-inch maximum.Distance from top of opening to throat F 8 inches Smoke chamber wall thickness
Unlined wallsG 6 inches
8 inchesChimney
Vertical reinforcingbH Four No. 4 full-length bars for chimney up to 40 inches wide.
Add two No. 4 bars for each additional 40 inches or fraction of
width or each additional flue.CRC § 2.1 High relevance — show source text
R1001.2 Footings and foundations. Footings for masonry fireplaces and their chimneys shall be constructed of concrete or solid masonry not less than 12 inches (305 mm) thick and shall extend not less than 6 inches (152 mm) beyond the face of the fireplace or foundation wall on all sides. Footings shall be founded on natural, undisturbed earth or engineered fill below frost depth. In areas not subjected to freezing, footings shall be not less than 12 inches (305 mm) below finished grade.
R1001.2.1 Ash dump cleanout. Cleanout openings located within foundation walls below fireboxes, where provided, shall be equipped with ferrous metal or masonry doors and frames constructed to remain tightly closed except when in use. Cleanouts shall be located to allow access so that ash removal will not create a hazard to combustible materials.
R1001.3 Seismic reinforcing. Masonry or concrete chimneys in all structures regulated by this code assigned to Seismic Design Category C, D 0, D 1 or D 2 shall be reinforced. Reinforcing shall conform to the requirements set forth in Table R1001.1 and Section R606.
R1001.3.1 Vertical reinforcing. For chimneys up to 40 inches (1016 mm) wide, four No. 4 continuous vertical bars shall be placed between wythes of solid masonry or within the cells of hollow unit masonry and grouted in accordance with Section R606. Grout
10-4 2025 CALIFORNIA RESIDENTIAL CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
CHIMNEYS AND FIREPLACES
shall be prevented from bonding with the flue liner so that the flue liner is free to move with thermal expansion. For chimneys more than 40 inches (1016 mm) wide, two additional No. 4 vertical bars shall be provided for each additional flue incorporated into the chimney or for each additional 40 inches (1016 mm) in width or fraction thereof. R1001.3.2 Horizontal reinforcing. Vertical reinforcement shall be placed within [1] / 4 -inch (6.4 mm) ties, or other reinforcing of equivalent net cross-sectional area, placed in the bed joints in accordance with Section R606 at not less than every 18 inches (457 mm) of vertical height. Two such ties shall be installed at each bend in the vertical bars.
R1001.4 Seismic anchorage. Masonry or concrete chimneys in all structures regulated by this code assigned to Seismic Design Category C, D 0, D 1 or D 2 shall be anchored at each floor, ceiling or roof line more than 6 feet (1829 mm) above grade, except where constructed completely within the exterior walls. Anchorage shall conform to the requirements of Section R1001.4.1. R1001.4.1 Anchorage. Two [3] / 16 -inch by 1-inch (5 mm by 25 mm) straps shall be embedded not less than 12 inches (305 mm) into the chimney. Straps shall be hooked around the outer bars and extend 6 inches (152 mm) beyond the bend. Each strap shall be fastened to not less than four floor ceiling or floor joists or rafters with two [1] / 2 -inch (12.7 mm) bolts. **R1001.4.1.1 Cold-formed steel framing.
CRC § 10-6 High relevance — show source text
internal heat exchange channels in which the flow path downstream of the firebox includes flow in a horizontal or downward direction before entering the chimney and that delivers heat by radiation from the masonry surface of the heater.
R1002.2 Installation. Masonry heaters shall be installed in accordance with this section and comply with one of the following:
- Masonry heaters shall comply with the requirements of ASTM E1602.
- Masonry heaters shall be listed and labeled in accordance with UL 1482 or CEN 15250 and installed in accordance with the manufacturer’s instructions.
R1002.3 Footings and foundation. The firebox floor of a masonry heater shall be a minimum thickness of 4 inches (102 mm) of noncombustible material and be supported on a noncombustible footing and foundation in accordance with Section R1003.2.
10-6 2025 CALIFORNIA RESIDENTIAL CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
CHIMNEYS AND FIREPLACES
R1002.4 Seismic reinforcing. In Seismic Design Categories D 0, D 1 and D 2, masonry heaters shall be anchored to the masonry foundation in accordance with Section R1003.3. Seismic reinforcing shall not be required within the body of a masonry heater whose height is equal to or less than 3.5 times its body width and where the masonry chimney serving the heater is not supported by the body of the heater. Where the masonry chimney shares a common wall with the facing of the masonry heater, the chimney portion of the structure shall be reinforced in accordance with Section R1003.
R1002.5 Masonry heater clearance. Combustible materials shall not be placed within 36 inches (914 mm) of the outside surface of a masonry heater in accordance with NFPA 211 Section 8-7 (clearances for solid-fuel-burning appliances), and the required space between the heater and combustible material shall be fully vented to permit the free flow of air around all heater surfaces.
Exceptions:
- Where the masonry heater wall is not less than 8 inches (203 mm) thick of solid masonry and the wall of the heat exchange channels is not less than 5 inches (127 mm) thick of solid masonry, combustible materials shall not be placed within 4 inches (102 mm) of the outside surface of a masonry heater. A clearance of not less than 8 inches (203 mm) shall be provided between the gas-tight capping slab of the heater and a combustible ceiling.
- Masonry heaters listed and labeled in accordance with UL 1482 or CEN 15250 shall be installed in accordance with the listing specifications and the manufacturer’s written instructions.
SECTION R1003—MASONRY CHIMNEYS
R1003.1 Definition. A masonry chimney is a chimney constructed of solid masonry units, hollow masonry units grouted solid, stone or concrete, hereinafter referred to as masonry. Masonry chimneys shall be constructed, anchored, supported and reinforced as required in this chapter.
CRC § 2025 High relevance — show source text
Chapter 6 also regulates exterior windows and doors installed in walls. This chapter contains criteria for the performance of exterior windows and doors and includes provisions for testing and labeling, garage doors, windborne debris protection and anchorage details.
Chapter 7 Wall Covering.
Chapter 7 contains provisions for the design and construction of interior and exterior wall coverings. This chapter establishes the various types of materials, materials standards and methods of application permitted for use as interior coverings, including interior plaster, gypsum board, ceramic tile, wood veneer paneling, hardboard paneling, wood shakes and wood shingles. Chapter 7 also contains requirements for the use of vapor retarders for moisture control in walls.
2025 CALIFORNIA RESIDENTIAL CODE xv
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
Exterior wall coverings provide the weather-resistant exterior envelope that protects the building’s interior from the elements. Chapter 7 provides the requirements for wind resistance and water-resistive barrier for exterior wall coverings. This chapter prescribes the exterior wall coverings as well as the water-resistive barrier required beneath the exterior materials. Exterior wall coverings regulated by this section include aluminum, stone and masonry veneer, wood, hardboard, particleboard, wood structural panel siding, wood shakes and shingles, exterior plaster, steel, vinyl, fiber cement and exterior insulation finish systems.
Chapter 8 Roof-Ceiling Construction.
Chapter 8 regulates the design and construction of roof-ceiling systems. This chapter contains two roof-ceiling framing systems: wood framing and cold-formed steel framing. Allowable span tables are provided to simplify the selection of rafter and ceiling joist size for wood roof framing and cold-formed steel framing. Chapter 8 also provides requirements for the application of ceiling finishes, the proper ventilation of concealed spaces in roofs (e.g., enclosed attics and rafter spaces), unvented attic assemblies and attic access.
Chapter 9 Roof Assemblies.
Chapter 9 regulates the design and construction of roof assemblies. A roof assembly includes the roof deck, vapor retarder, substrate or thermal barrier, insulation, vapor retarder and roof covering. This chapter provides the requirement for wind resistance of roof coverings.
The types of roof covering materials and installation regulated by Chapter 9 are: asphalt shingles, clay and concrete tile, metal roof shingles, mineral-surfaced roll roofing, slate and slate-type shingles, wood shakes and shingles, built-up roofs, metal roof panels, modified bitumen roofing, thermoset and thermoplastic single-ply roofing, sprayed polyurethane foam roofing, liquid applied coatings and photovoltaic shingles. Chapter 9 also provides requirements for roof drainage, flashing, above deck thermal insulation, rooftop-mounted photovoltaic systems and recovering or replacing an existing roof covering.
Chapter 10 Chimneys and Fireplaces.
Chapter 10 contains requirements for the safe construction of masonry chimneys and fireplaces and establishes the standards for the use and installation of factory-built chimneys, fireplaces and masonry heaters. Chimneys and fireplaces constructed of masonry rely on prescriptive requirements for the details of their construction; the factory-built type relies on the listing and labeling method of approval. Chapter 10 provides the requirements for seismic reinforcing and anchorage of masonry fireplaces and chimneys.
Chapter 11 [RE] Energy Efficiency.
Chapter 11 is not adopted in California. See California Energy Code, Title 24, Part 6.
Chapter 12 Mechanical Administration.
CRC § 25.4 High relevance — show source text
FIGURE R1003.20—CHIMNEY CRICKET
AIRSPACE
ROOF LINE
For SI: 1 inch = 25.4 mm.
FLUE LINER Col2 Col3 Col4 Col5 1 IN.
AIRS1 IN.
AIRS1 IN.
AIRS1 IN.
AIRS1 IN.
AIRSW W W W W 2025 CALIFORNIA RESIDENTIAL CODE 10-11
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
�
CHIMNEYS AND FIREPLACES
SECTION R1004—FACTORY-BUILT FIREPLACES
R1004.1 General. Factory-built fireplaces shall be listed and labeled and shall be installed in accordance with the conditions of the listing. Factory-built fireplaces shall be tested in accordance with UL 127.
R1004.1.1 Factory-built wood burning fireplaces. Factory-built wood burning fireplaces shall be qualified at the U.S. EPA’s Volun- tary Fireplace Program Phase 2 emissions level and be in accordance with the California Green Building Standards Code, Chapter 4, Division 4.5.
R1004.2 Hearth extensions. Hearth extensions of approved factory-built fireplaces shall be installed in accordance with the listing of the fireplace. The hearth extension shall be readily distinguishable from the surrounding floor area. Listed and labeled hearth extensions shall comply with UL 1618.
R1004.3 Decorative shrouds. Decorative shrouds shall not be installed at the termination of chimneys for factory-built fireplaces except where the shrouds are listed and labeled for use with the specific factory-built fireplace system and installed in accordance with the manufacturer’s instructions.
R1004.5 Gasketed fireplace doors. A gasketed fireplace door shall not be installed on a factory-built fireplace except where the fireplace system has been specifically tested, listed and labeled for such use in accordance with UL 127.
SECTION R1005—FACTORY-BUILT CHIMNEYS
R1005.1 Listing. Factory-built chimneys shall be listed and labeled and shall be installed and terminated in accordance with the manufacturer’s installation instructions.
R1005.2 Decorative shrouds. Decorative shrouds shall not be installed at the termination of factory-built chimneys except where the shrouds are listed and labeled for use with the specific factory-built chimney system and installed in accordance with the manufacturer’s installation instructions.
R1005.3 Solid-fuel appliances. Factory-built chimneys installed in dwelling units with solid-fuel-burning appliances shall comply with the Type HT requirements of UL 103 and shall be marked “Type HT” and “Residential Type and Building Heating Appliance Chimney.”
Exception: Chimneys for use with open combustion chamber fireplaces shall comply with the requirements of UL 103 and shall be marked “Residential Type and Building Heating Appliance Chimney.”
Chimneys for use with open combustion chamber appliances installed in buildings other than dwelling units shall comply with the requirements of UL 103 and shall be marked “Building Heating Appliance Chimney” or “Residential Type and Building Heating Appliance Chimney.”
R1005.4 Factory-built fireplaces. Chimneys for use with factory-built fireplaces shall comply with the requirements of UL 127.
CRC § 25.4 High relevance — show source text
SECTION R1001—MASONRY FIREPLACES
R1001.1 General. Masonry fireplaces shall be constructed in accordance with this section and the applicable provisions of Chapters 3 and 4.
TABLE R1001.1—SUMMARY OF REQUIREMENTS FOR MASONRY FIREPLACES AND CHIMNEYS Col2 Col3 ** ITEM** ** LETTERa** ** REQUIREMENTS** Hearth slab thickness A 4 inches Hearth extension (each side of opening) B 8-inch fireplace opening < 6 square feet.
12-inch fireplace opening ≥ 6 square feet.Hearth extension (front of opening) C 16-inch fireplace opening < 6 square feet.
20-inch fireplace opening ≥ 6 square feet.Hearth slab reinforcing D Reinforced to carry its own weight and all imposed loads. Thickness of wall of firebox E 10-inch solid brick or 8 inches where a firebrick lining is used.
Joints in firebrick1/4-inch maximum.Distance from top of opening to throat F 8 inches Smoke chamber wall thickness
Unlined wallsG 6 inches
8 inchesChimney
Vertical reinforcingbH Four No. 4 full-length bars for chimney up to 40 inches wide.
Add two No. 4 bars for each additional 40 inches or fraction of
width or each additional flue.Horizontal reinforcing J 1/4-inch ties at 18 inches and two ties at each bend in vertical steel. Bond beams K No specified requirements. Fireplace lintel L Noncombustible material. Chimney walls with flue lining M Solid masonry units or hollow masonry units grouted solid with not
less than 4-inch nominal thickness.Distances between adjacent flues — See Section R1003.13. Effective flue area (based on area of fireplace opening) P See Section R1003.15. Clearances
Combustible material
Mantel and trim
Above roofR See Sections R1001.11 and R1003.18.
See Section R1001.11, Exception 4.
3 feet at roofline and 2 feet at 10 feet.Anchorageb
Strap Number
Embedment into chimney
Fasten to
BoltsS 3/16-inch × 1-inch
Two
12 inches hooked around outer bar with 6-inch extension.
4 joists
Two1/2-inch diameter.Footing
Thickness
WidthT 12 inches min.
6 inches each side of fireplace wall.For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 square foot = 0.0929 m2.
Note: This table provides a summary of major requirements for the construction of masonry chimneys and fireplaces. Letter references are to Figure R1001.1, which shows
examples of typical construction. This table does not cover all requirements, nor does it cover all aspects of the indicated requirements. For the actual mandatory require-
ments of the code, see the indicated section of text.
a. The letters refer to Figure R1001.1.
b.CRC § 9-4 High relevance — show source text
R904 Materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-4
R905 Requirements for Roof Coverings . . . . . . . . . . . . . . . . 9-4
R906 Roof Insulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-19
R907 Rooftop-Mounted Photovoltaic Panel Systems . . . 9-19
R908 Reroofing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-19
R909 Roof Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-20
CHAPTER 10 CHIMNEYS AND FIREPLACES . . . . . . . . . . . .10-3
R1001 Masonry Fireplaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-3
R1002 Masonry Heaters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-6
R1003 Masonry Chimneys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-7
R1004 Factory-Built Fireplaces. . . . . . . . . . . . . . . . . . . . . . . . 10-12
R1005 Factory-Built Chimneys . . . . . . . . . . . . . . . . . . . . . . . . 10-12
R1006 Exterior Air Supply. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-12
Part IV—Energy Conservation. . . . . . . . . . . . . . . . . . . . . . . .11-1
Part V—Mechanical. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12-1
Part VI—Fuel Gas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24-1
Part VII—Plumbing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25-1
Part VIII—Electrical. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34-1
Part IX— Referenced Standards . . . . . . . . . . . . . . . . . . . . . .44-3
CHAPTER 44 REFERENCED STANDARDS . . . . . . . . . . . . . .44-3
CRC § 10.1 Medium relevance — show source text
R1003.10 Wall thickness. Masonry chimney walls shall be constructed of solid masonry units or hollow masonry units grouted solid with not less than a 4-inch (102 mm) nominal thickness.
R1003.10.1 Masonry veneer chimneys. Where masonry is used to veneer a frame chimney, through-flashing and weep holes shall be installed as required by Section R703.
R1003.11 Flue lining (material). Masonry chimneys shall be lined. The lining material shall be appropriate for the type of appliance connected, in accordance with the terms of the appliance listing and manufacturer’s instructions.
R1003.11.1 Residential-type appliances (general). Flue lining systems shall comply with one of the following:
- Clay flue lining complying with the requirements of ASTM C315.
- Listed and labeled chimney lining systems complying with UL 1777.
- Factory-built chimneys or chimney units listed for installation within masonry chimneys.
- Other approved materials that will resist corrosion, erosion, softening or cracking from flue gases and condensate at temperatures up to 1,800°F (982°C).
R1003.11.2 Flue linings for specific appliances. Flue linings other than these covered in Section R1003.11.1, intended for use with specific types of appliances, shall comply with Sections R1003.11.3 through R1003.11.6.
R1003.11.3 Gas appliances. Flue lining systems for gas appliances shall be in accordance with the California Mechanical Code.
R1003.11.4 Pellet fuel-burning appliances. Flue lining and vent systems for use in masonry chimneys with pellet fuel-burning appliances shall be limited to the following:
- Flue lining systems complying with Section R1003.11.1.
- Pellet vents listed for installation within masonry chimneys (see Section R1003.11.6 for marking).
R1003.11.5 Oil-fired appliances approved for use with Type L vent. Flue lining and vent systems for use in masonry chimneys with oil-fired appliances approved for use with Type L vent shall be limited to the following:
- Flue lining systems complying with Section R1003.11.1.
- Listed chimney liners complying with UL 641 (see Section R1003.11.6 for marking).
R1003.11.6 Notice of usage. Where a flue is relined with a material not complying with Section R1003.11.1, the chimney shall be plainly and permanently identified by a label attached to a wall, ceiling or other conspicuous location adjacent to where the connector enters the chimney. The label shall include the following message or equivalent language:
THIS CHIMNEY FLUE IS FOR USE ONLY WITH [TYPE OR CATEGORY OF APPLIANCE] APPLIANCES THAT BURN [TYPE OF FUEL]. DO NOT CONNECT OTHER TYPES OF APPLIANCES.
R1003.12 Clay flue lining (installation). Clay flue liners shall be installed in accordance with ASTM C1283 and extend from a point not less than 8 inches (203 mm) below the lowest inlet or, in the case of fireplaces, from the top of the smoke chamber to a point above the enclosing walls. The lining shall be carried up vertically, with a slope not greater than 30 degrees (0.52 rad) from the vertical.
CRC § 25.4 Medium relevance — show source text
| |Fireplace lintel|L|Noncombustible material.| |Chimney walls with flue lining|M|Solid masonry units or hollow masonry units grouted solid with not
less than 4-inch nominal thickness.| |Distances between adjacent flues|—|See Section R1003.13.| |Effective flue area (based on area of fireplace opening)|P|See Section R1003.15.| |Clearances
Combustible material
Mantel and trim
Above roof|R|See Sections R1001.11 and R1003.18.
See Section R1001.11, Exception 4.
3 feet at roofline and 2 feet at 10 feet.| |Anchorageb
Strap Number
Embedment into chimney
Fasten to
Bolts|S|3/16-inch × 1-inch
Two
12 inches hooked around outer bar with 6-inch extension.
4 joists
Two1/2-inch diameter.| |Footing
Thickness
Width|T|12 inches min.
6 inches each side of fireplace wall.| |For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 square foot = 0.0929 m2.
Note: This table provides a summary of major requirements for the construction of masonry chimneys and fireplaces. Letter references are to Figure R1001.1, which shows
examples of typical construction. This table does not cover all requirements, nor does it cover all aspects of the indicated requirements. For the actual mandatory require-
ments of the code, see the indicated section of text.
a. The letters refer to Figure R1001.1.
b. Not required in Seismic Design Category A or B.|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 square foot = 0.0929 m2.
Note: This table provides a summary of major requirements for the construction of masonry chimneys and fireplaces. Letter references are to Figure R1001.1, which shows
examples of typical construction. This table does not cover all requirements, nor does it cover all aspects of the indicated requirements. For the actual mandatory require-
ments of the code, see the indicated section of text.
a. The letters refer to Figure R1001.1.
b. Not required in Seismic Design Category A or B.|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 square foot = 0.0929 m2.
Note: This table provides a summary of major requirements for the construction of masonry chimneys and fireplaces. Letter references are to Figure R1001.1, which shows
examples of typical construction. This table does not cover all requirements, nor does it cover all aspects of the indicated requirements. For the actual mandatory require-
ments of the code, see the indicated section of text.
a. The letters refer to Figure R1001.1.
b. Not required in Seismic Design Category A or B.|2025 CALIFORNIA RESIDENTIAL CODE 10-3
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
CHIMNEYS AND FIREPLACES
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm.
CRC § 8-3 Medium relevance — show source text
R802 Wood Roof Framing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3
R803 Roof Sheathing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-30
R804 Cold-Formed Steel Roof Framing . . . . . . . . . . . . . . . 8-31
R805 Ceiling Finishes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-44
R806 Roof Ventilation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-44
R807 Attic Access. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-46
CHAPTER 9 ROOF ASSEMBLIES . . . . . . . . . . . . . . . . . . . . . .9-3
R901 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-3
R902 Fire Classification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-3
R903 Weather Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-4
R904 Materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-4
R905 Requirements for Roof Coverings . . . . . . . . . . . . . . . . 9-4
R906 Roof Insulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-19
R907 Rooftop-Mounted Photovoltaic Panel Systems . . . 9-19
R908 Reroofing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-19
R909 Roof Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-20
CHAPTER 10 CHIMNEYS AND FIREPLACES . . . . . . . . . . . .10-3
R1001 Masonry Fireplaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-3
R1002 Masonry Heaters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-6
R1003 Masonry Chimneys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-7
Frequently asked questions
Are masonry chimneys required to be seismically reinforced?
Yes. Masonry and concrete chimneys must be reinforced and anchored where the structure is in Seismic Design Category C, D0, D1 or D2; reinforcement and anchorage details are in §R1003.3 (and related subsections).
Can I use a factory‑built fireplace or chimney?
Yes — factory‑built fireplaces and chimneys are permitted but must be listed and labeled and installed in accordance with their listing and manufacturer instructions. Factory‑built fireplaces are addressed in §R1004 and factory chimneys in §R1005; wood‑burning factory units have additional emissions and listing requirements.
What flue‑lining options does the CRC allow for masonry chimneys?
Masonry chimneys must be lined. Acceptable lining systems include clay flue liners meeting ASTM C315, listed chimney‑lining systems complying with UL 1777, listed factory‑built chimney units installed within masonry, or other approved materials rated for the appliance’s flue gas temperatures; see §R1003.11 for details.
More in California Residential Code
Ask about the CRC
Get cited, plain-English answers on the California Residential Code for your project — any code section, any scenario.
Start Free Trial