Masonry Fireplaces

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

• CRC § 0.6 High relevance — show source text

  R1001.10 Hearth extension dimensions. Hearth extensions shall extend not less than 16 inches (406 mm) in front of and not less than 8 inches (203 mm) beyond each side of the fireplace opening. Where the fireplace opening is 6 square feet (0.6 m [2] ) or larger, the hearth extension shall extend not less than 20 inches (508 mm) in front of and not less than 12 inches (305 mm) beyond each side of the fireplace opening.

  R1001.11 Fireplace clearance. Wood beams, joists, studs and other combustible material shall have a clearance of not less than 2 inches (51 mm) from the front faces and sides of masonry fireplaces and not less than 4 inches (102 mm) from the back faces of masonry fireplaces. The airspace shall not be filled, except for noncombustible material or to provide fireblocking in accordance with Section R1001.12.

  Exceptions:

  1. Masonry fireplaces listed and labeled for use in contact with combustibles in accordance with UL 127 and installed in accordance with the manufacturer’s instructions are permitted to have combustible material in contact with their exterior surfaces.

  2. Where masonry fireplaces are part of masonry or concrete walls, combustible materials shall not be in contact with the masonry or concrete walls less than 12 inches (306 mm) from the inside surface of the nearest firebox lining.

  3. Exposed combustible trim and the edges of sheathing materials such as wood siding, flooring and gypsum board shall be permitted to abut the masonry fireplace sidewalls and hearth extension in accordance with Figure R1001.11, provided that such combustible trim or sheathing is not less than 8 inches (203 mm) from the inside surface of the nearest firebox

  For SI: 1 inch = 25.4 mm.

  masonry, that is designed to absorb and store heat from a solid-fuel fire built in the firebox by routing the exhaust gases through

  |e fireplace opening is 6 square feet (0.6 m2) or larger, such combustible tri
  masonry fireplace sidewalls and hearth extension provided that such co
  inches (305 mm) from the inside surface of the nearest firebox lining.
  ustible mantels or trim is permitted to be placed directly on the masonry f
  ng providing such combustible materials are not placed within 6 inches (1
  aterial within 12 inches (306 mm) of the fireplace opening shall not projec
  mm) distance from such an opening.
  FIGURE R1001.11—CLEARANCE FROM COMBUSTIBLES
  MASONRY
  COMBUSTIBLE SHEATHING
  EDGE ABUTTING MASONRY
  12 IN. FROM FIREBOX
  FRAME WALL
  2 IN. CLEARANCE (AIRSPA
  TO COMBUSTIBLE FRAMIN
  WOOD MANTEL
  cking. Fireplace fireblocking shall comply with the provisions of Section R
  ories. Listed and labeled fireplace accessories shall be installed in accorda
  r’s instructions.

• 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 walls	G	6 inches 8 inches
  Chimney Vertical reinforcingb	H	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 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.

• 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: †

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  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 walls	G	6 inches 8 inches
  Chimney Vertical reinforcingb	H	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 § 2111.7 High relevance — show source text

  The firebox lining shall be encased with solid masonry to provide a total thickness at the back and sides of not less than 8 inches (203 mm), of which not less than 4 inches (102 mm) shall be of solid masonry or concrete. Circulating air ducts employed with steel fireplace units shall be constructed of metal or masonry.

  2111.7 Firebox dimensions. The firebox of a concrete or masonry fireplace shall have a minimum depth of 20 inches (508 mm). The throat shall be not less than 8 inches (203 mm) above the fireplace opening. The throat opening shall be not less than 4 inches (102 mm) in depth. The cross-sectional area of the passageway above the firebox, including the throat, damper and smoke chamber, shall be not less than the cross-sectional area of the flue.

  Exception: Rumford fireplaces shall be permitted provided that the depth of the fireplace is not less than 12 inches (305 mm) and not less than one-third of the width of the fireplace opening, and the throat is not less than 12 inches (305 mm) above the lintel, and not less than [1] / 20 the cross-sectional area of the fireplace opening.

  2111.8 Lintel and throat. Masonry over a fireplace opening shall be supported by a lintel of noncombustible material. The minimum required bearing length on each end of the fireplace opening shall be 4 inches (102 mm). The fireplace throat or damper shall be located not less than 8 inches (203 mm) above the top of the fireplace opening.

  2111.8.1 Damper. Masonry fireplaces shall be equipped with a ferrous metal damper located not less than 8 inches (203 mm) above the top of the fireplace opening. Dampers shall be installed in the fireplace or at the top of the flue venting the fireplace, and shall be operable from the room containing the fireplace. Damper controls shall be permitted to be located in the fireplace.

  2111.9 Smoke chamber walls. Smoke chamber walls shall be constructed of solid masonry units, hollow masonry units grouted solid, stone or concrete. The total minimum thickness of front, back and sidewalls shall be 8 inches (203 mm) of solid masonry. The inside surface shall be parged smooth with refractory mortar conforming to ASTM C199. Where a lining of firebrick not less than 2 inches (51 mm) thick, or a lining of vitrified clay not less than [5] / 8 inch (15.9 mm) thick, is provided, the total minimum thickness of front, back and sidewalls shall be 6 inches (152 mm) of solid masonry, including the lining. Firebrick shall conform to ASTM C1261 and shall be laid with refractory mortar conforming to ASTM C199. Vitrified clay linings shall conform to ASTM C315.

  2111.9.1 Smoke chamber dimensions. The inside height of the smoke chamber from the fireplace throat to the beginning of the flue shall be not greater than the inside width of the fireplace opening. The inside surface of the smoke chamber shall not be inclined more than 45 degrees (0.76 rad) from vertical where prefabricated smoke chamber linings are used or where the smoke chamber walls are rolled or sloped rather than corbeled. Where the inside surface of the smoke chamber is formed by corbeled masonry, the walls shall not be corbeled more than 30 degrees (0.52 rad) from vertical.

• CRC § 1.1 High relevance — show source text

  SECTION R1006—EXTERIOR AIR SUPPLY

  R1006.1 Exterior air. Factory-built or masonry fireplaces covered in this chapter shall be equipped with an exterior air supply to ensure proper fuel combustion unless the room is mechanically ventilated and controlled so that the indoor pressure is neutral or positive.

  R1006.1.1 Factory-built fireplaces. Exterior combustion air ducts for factory-built fireplaces shall be a listed component of the fireplace and shall be installed in accordance with the fireplace manufacturer’s instructions.

  R1006.1.2 Masonry fireplaces. Listed combustion air ducts for masonry fireplaces shall be installed in accordance with the terms of their listing and the manufacturer’s instructions.

  R1006.2 Exterior air intake. The exterior air intake shall be capable of supplying all combustion air from the exterior of the dwelling unit or from spaces within the dwelling unit ventilated with outdoor air such as nonmechanically ventilated crawl or attic spaces. The

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  CHIMNEYS AND FIREPLACES

  exterior air intake shall not be located within the garage or basement of the dwelling unit. The exterior air intake, for other than listed factory-built fireplaces, shall not be located at an elevation higher than the firebox. The exterior air intake shall be covered with a corrosion-resistant screen of [1] / 4 -inch (6.4 mm) mesh.

  R1006.3 Clearance. Unlisted c ombustion air ducts shall be installed with a minimum 1-inch (25 mm) clearance to combustibles for all parts of the duct within 5 feet (1524 mm) of the duct outlet. R1006.4 Passageway. The combustion air passageway shall be not less than 6 square inches (3870 mm [2] ) and not more than 55 square inches (0.035 m [2] ), except that combustion air systems for listed fireplaces shall be constructed in accordance with the fireplace manufacturer’s instructions.

  R1006.5 Outlet. The exterior air outlet shall be located in the back or side of the firebox chamber or shall be located outside of the firebox, at the level of the hearth and not greater than 24 inches (610 mm) from the firebox opening. The outlet shall be closable and designed to prevent burning material from dropping into concealed combustible spaces.

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  Part IV—Energy Conservation

  (Note: Part IV is not adopted. See California Energy Code, Title 24, Part 6.)

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  Part V—Mechanical

  (Note: Part V is not adopted. See California Mechanical Code, Title 24, Part 4.)

• CRC § 8.1 High relevance — show source text

  R1001.8.1 Smoke chamber dimensions. The inside height of the smoke chamber from the fireplace throat to the beginning of the flue shall not be greater than the inside width of the fireplace opening. The inside surface of the smoke chamber shall not be inclined more than 45 degrees (0.79 rad) from vertical where prefabricated smoke chamber linings are used or where the smoke chamber walls are rolled or sloped rather than corbeled. Where the inside surface of the smoke chamber is formed by corbeled masonry, the walls shall not be corbeled more than 30 degrees (0.52 rad) from vertical.

  R1001.9 Hearth and hearth extension. Masonry fireplace hearths and hearth extensions shall be constructed of concrete or masonry, supported by noncombustible materials, and reinforced to carry their own weight and all imposed loads. Combustible material shall not remain against the underside of hearths and hearth extensions after construction.

  R1001.9.1 Hearth thickness. The minimum thickness of fireplace hearths shall be 4 inches (102 mm).

  R1001.9.2 Hearth extension thickness. The minimum thickness of hearth extensions shall be 2 inches (51 mm).

  Exception: Where the bottom of the firebox opening is raised not less than 8 inches (203 mm) above the top of the hearth extension, a hearth extension of not less than [3] / 8 -inch-thick (10 mm) brick, concrete, stone, tile or other approved noncombustible material is permitted.

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  CHIMNEYS AND FIREPLACES

  R1001.10 Hearth extension dimensions. Hearth extensions shall extend not less than 16 inches (406 mm) in front of and not less than 8 inches (203 mm) beyond each side of the fireplace opening. Where the fireplace opening is 6 square feet (0.6 m [2] ) or larger, the hearth extension shall extend not less than 20 inches (508 mm) in front of and not less than 12 inches (305 mm) beyond each side of the fireplace opening.

  R1001.11 Fireplace clearance. Wood beams, joists, studs and other combustible material shall have a clearance of not less than 2 inches (51 mm) from the front faces and sides of masonry fireplaces and not less than 4 inches (102 mm) from the back faces of masonry fireplaces. The airspace shall not be filled, except for noncombustible material or to provide fireblocking in accordance with Section R1001.12.

  Exceptions:

  1. Masonry fireplaces listed and labeled for use in contact with combustibles in accordance with UL 127 and installed in accordance with the manufacturer’s instructions are permitted to have combustible material in contact with their exterior surfaces.

  2. Where masonry fireplaces are part of masonry or concrete walls, combustible materials shall not be in contact with the masonry or concrete walls less than 12 inches (306 mm) from the inside surface of the nearest firebox lining.

  3. Exposed combustible trim and the edges of sheathing materials such as wood siding, flooring and gypsum board shall be permitted to abut the masonry fireplace sidewalls and hearth extension in accordance with Figure R1001.11, provided that such combustible trim or sheathing is not less than 8 inches (203 mm) from the inside surface of the nearest firebox

• CRC § 2111.10.1 High relevance — show source text

  2111.10.1 Hearth thickness. The minimum thickness of fireplace hearths shall be 4 inches (102 mm).

  2111.10.2 Hearth extension thickness. The minimum thickness of hearth extensions shall be 2 inches (51 mm).

  Exception: Where the bottom of the firebox opening is raised not less than 8 inches (203 mm) above the top of the hearth extension, a hearth extension of not less than [3] / 8 -inch-thick (9.5 mm) brick, concrete, stone, tile or other approved noncombustible material is permitted.

  2111.11 Hearth extension dimensions. Hearth extensions shall extend not less than 16 inches (406 mm) in front of, and not less than 8 inches (203 mm) beyond, each side of the fireplace opening. Where the fireplace opening is 6 square feet (0.557 m [2] ) or larger, the hearth extension shall extend not less than 20 inches (508 mm) in front of, and not less than 12 inches (305 mm) beyond, each side of the fireplace opening.

  2111.12 Fireplace clearance. Any portion of a masonry fireplace located in the interior of a building or within the exterior wall of a building shall have a clearance to combustibles of not less than 2 inches (51 mm) from the front faces and sides of masonry fireplaces and not less than 4 inches (102 mm) from the back faces of masonry fireplaces. The airspace shall not be filled, except to provide fireblocking in accordance with Section 2111.13.

  Exceptions:

  1. Masonry fireplaces listed and labeled for use in contact with combustibles in accordance with UL 127 and installed in accordance with the manufacturer’s instructions are permitted to have combustible material in contact with their exterior surfaces.

  2. Where masonry fireplaces are constructed as part of masonry or concrete walls, combustible materials shall not be in contact with the masonry or concrete walls less than 12 inches (306 mm) from the inside surface of the nearest firebox lining.

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  3. Exposed combustible trim and the edges of sheathing materials, such as wood siding, flooring and drywall, are permitted to abut the masonry fireplace sidewalls and hearth extension, in accordance with Figure 2111.12, provided that such combustible trim or sheathing is not less than 12 inches (306 mm) from the inside surface of the nearest firebox lining.
  4. Exposed combustible mantels or trim is permitted to be placed directly on the masonry fireplace front surrounding the fireplace opening, provided that such combustible materials shall not be placed within 6 inches (153 mm) of a fireplace opening. Combustible material directly above and within 12 inches (305 mm) of the fireplace opening shall not project more than [1] / 8 inch (3.2 mm) for each 1-inch (25 mm) distance from such opening. Combustible materials located along the sides of the fireplace opening that project more than 1 [1] / 2 inches (38 mm) from the face of the fireplace shall have an additional clearance equal to the projection.

  FIGURE 2111.12—ILLUSTRATION OF EXCEPTION TO FIREPLACE CLEARANCE PROVISION

  EDGE ABUTTING MASONRY

  2 ″ CLEARANCE (AIRSPACE) TO COMBUSTIBLE FRAMING

• CRC § 7.1 High relevance — show source text

  R1001.7 Lintel and throat. Masonry over a fireplace opening shall be supported by a lintel of noncombustible material. The minimum required bearing length on each end of the fireplace opening shall be 4 inches (102 mm). The fireplace throat or damper shall be located not less than 8 inches (203 mm) above the lintel.

  R1001.7.1 Damper. Masonry fireplaces shall be equipped with a ferrous metal damper located not less than 8 inches (203 mm) above the top of the fireplace opening. Dampers shall be installed in the fireplace or the chimney venting the fireplace, and shall be operable from the room containing the fireplace.

  R1001.8 Smoke chamber. Smoke chamber walls shall be constructed of solid masonry units, hollow masonry units grouted solid, stone or concrete. The total minimum thickness of front, back and side walls shall be 8 inches (203 mm) of solid masonry. The inside surface shall be parged smooth with refractory mortar conforming to ASTM C199. Where a lining of firebrick not less than 2 inches (51 mm) thick, or a lining of vitrified clay not less than [5] / 8 inch (16 mm) thick, is provided, the total minimum thickness of front, back and side walls shall be 6 inches (152 mm) of solid masonry, including the lining. Firebrick shall conform to ASTM C1261 and shall be laid with medium-duty refractory mortar conforming to ASTM C199. Vitrified clay linings shall conform to ASTM C315.

  R1001.8.1 Smoke chamber dimensions. The inside height of the smoke chamber from the fireplace throat to the beginning of the flue shall not be greater than the inside width of the fireplace opening. The inside surface of the smoke chamber shall not be inclined more than 45 degrees (0.79 rad) from vertical where prefabricated smoke chamber linings are used or where the smoke chamber walls are rolled or sloped rather than corbeled. Where the inside surface of the smoke chamber is formed by corbeled masonry, the walls shall not be corbeled more than 30 degrees (0.52 rad) from vertical.

  R1001.9 Hearth and hearth extension. Masonry fireplace hearths and hearth extensions shall be constructed of concrete or masonry, supported by noncombustible materials, and reinforced to carry their own weight and all imposed loads. Combustible material shall not remain against the underside of hearths and hearth extensions after construction.

  R1001.9.1 Hearth thickness. The minimum thickness of fireplace hearths shall be 4 inches (102 mm).

  R1001.9.2 Hearth extension thickness. The minimum thickness of hearth extensions shall be 2 inches (51 mm).

  Exception: Where the bottom of the firebox opening is raised not less than 8 inches (203 mm) above the top of the hearth extension, a hearth extension of not less than [3] / 8 -inch-thick (10 mm) brick, concrete, stone, tile or other approved noncombustible material is permitted.

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• 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 § 25.4 Medium 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.|

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  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

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• CRC § 21-12 Medium relevance — show source text

  2. Where masonry fireplaces are constructed as part of masonry or concrete walls, combustible materials shall not be in contact with the masonry or concrete walls less than 12 inches (306 mm) from the inside surface of the nearest firebox lining.

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  MASONRY

  3. Exposed combustible trim and the edges of sheathing materials, such as wood siding, flooring and drywall, are permitted to abut the masonry fireplace sidewalls and hearth extension, in accordance with Figure 2111.12, provided that such combustible trim or sheathing is not less than 12 inches (306 mm) from the inside surface of the nearest firebox lining.
  4. Exposed combustible mantels or trim is permitted to be placed directly on the masonry fireplace front surrounding the fireplace opening, provided that such combustible materials shall not be placed within 6 inches (153 mm) of a fireplace opening. Combustible material directly above and within 12 inches (305 mm) of the fireplace opening shall not project more than [1] / 8 inch (3.2 mm) for each 1-inch (25 mm) distance from such opening. Combustible materials located along the sides of the fireplace opening that project more than 1 [1] / 2 inches (38 mm) from the face of the fireplace shall have an additional clearance equal to the projection.

  FIGURE 2111.12—ILLUSTRATION OF EXCEPTION TO FIREPLACE CLEARANCE PROVISION

  EDGE ABUTTING MASONRY

  2 ″ CLEARANCE (AIRSPACE) TO COMBUSTIBLE FRAMING

  For SI: 1 inch = 25.4 mm

  2111.13 Fireplace fireblocking. All spaces between fireplaces and floors and ceilings through which fireplaces pass shall be fireblocked with noncombustible material securely fastened in place. The fireblocking of spaces between wood joists, beams or headers shall be to a depth of 1 inch (25 mm) and shall only be placed on strips of metal or metal lath laid across the spaces between combustible material and the chimney.

  2111.14 Exterior air. Factory-built or masonry fireplaces covered in this section shall be equipped with an exterior air supply to ensure proper fuel combustion unless the room is mechanically ventilated and controlled so that the indoor pressure is neutral or positive.

  2111.14.1 Factory-built fireplaces. Exterior combustion air ducts for factory-built fireplaces shall be listed components of the fireplace, and installed according to the fireplace manufacturer’s instructions.

  MASONRY COMBUSTIBL EDGE ABUTTI 12″ MIN FROM 2″ CLEAR TO COMB FRAME W WOOD MANT spaces between fireplaces and floors and al securely fastened in place. The fireblock nd shall only be placed on strips of metal r masonry fireplaces covered in this sect s the room is mechanically ventilated an es. Exterior combustion air ducts for fact o the fireplace manufacturer’s instruction	COMBUSTIBL EDGE ABUTTI 12″ MIN FROM 2″ CLEAR TO COMB	Col3
  spaces between fireplaces and floors and al securely fastened in place.

• CRC § 21-17 Medium relevance — show source text

  2025 CALIFORNIA BUILDING CODE 21-17

  on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

  MASONRY

  TABLE 2113.16(2)—NET CROSS-SECTIONAL AREA OF SQUARE AND RECTANGULAR FLUE SIZES—continued	Col2
  FLUE SIZE, OUTSIDE NOMINAL DIMENSIONS (inches)	CROSS-SECTIONAL AREA (square inches)
  13 × 18	173
  16 × 16	181
  16 × 20	222
  18 × 18	233
  20 × 20	298
  20 × 24	335
  24 × 24	431
  For SI: 1 inch = 25.4 mm, 1 square inch = 645.16 mm2.	For SI: 1 inch = 25.4 mm, 1 square inch = 645.16 mm2.

  2113.16.1 Minimum area. Round chimney flues shall have a minimum net cross-sectional area of not less than [1] / 12 of the fireplace opening. Square chimney flues shall have a minimum net cross-sectional area of not less than [1] / 10 of the fireplace opening. Rectangular chimney flues with an aspect ratio less than 2 to 1 shall have a minimum net cross-sectional area of not less than [1] / 10 of the fireplace opening. Rectangular chimney flues with an aspect ratio of 2 to 1 or more shall have a minimum net cross-sectional area of not less than [1] / 8 of the fireplace opening.

  2113.16.2 Determination of minimum area. The minimum net cross-sectional area of the flue shall be determined in accordance with Figure 2113.16. A flue size providing not less than the equivalent net cross-sectional area shall be used. Cross-sectional areas of clay flue linings are as provided in Tables 2113.16(1) and 2113.16(2) or as provided by the manufacturer or as measured in the field. The height of the chimney shall be measured from the firebox floor to the top of the chimney flue.

  2113.17 Inlet. Inlets to masonry chimneys shall enter from the side. Inlets shall have a thimble of fireclay, rigid refractory material or metal that will prevent the connector from pulling out of the inlet or from extending beyond the wall of the liner.

  2113.18 Masonry chimney cleanout openings. Cleanout openings shall be provided within 6 inches (152 mm) of the base of each flue within every masonry chimney. The upper edge of the cleanout shall be located not less than 6 inches (152 mm) below the lowest chimney inlet opening. The height of the opening shall be not less than 6 inches (152 mm). The cleanout shall be provided with a noncombustible cover.

  Exception: Chimney flues serving masonry fireplaces, where cleaning is possible through the fireplace opening.

  2113.19 Chimney clearances. Any portion of a masonry chimney located in the interior of the building or within the exterior wall of the building shall have a minimum airspace clearance to combustibles of 2 inches (51 mm). Chimneys located entirely outside the exterior walls of the building, including chimneys that pass through the soffit or cornice, shall have a minimum airspace clearance of 1 inch (25 mm). The airspace shall not be filled, except to provide fireblocking in accordance with Section 2113.20.