Masonry Heaters & Exterior Air Supply

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

• 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

  10-12 2025 CALIFORNIA RESIDENTIAL CODE

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

  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.

  2025 CALIFORNIA RESIDENTIAL CODE 10-13

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

  10-14 2025 CALIFORNIA RESIDENTIAL CODE

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

  Part IV—Energy Conservation

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

  2025 CALIFORNIA RESIDENTIAL CODE 11-1

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

  11-2 2025 CALIFORNIA RESIDENTIAL CODE

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

  Part V—Mechanical

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

• CRC § 0.52 Medium relevance — show source text

  R1005.6 Medium-heat appliances. Factory-built chimneys for medium-heat appliances producing flue gases having a temperature above 1,000°F (538°C), measured at the entrance to the chimney, shall comply with UL 959.

  R1005.7 Factory-built chimney offsets. Where a factory-built chimney assembly incorporates offsets, no part of the chimney shall be at an angle of more than 30 degrees (0.52 rad) from vertical at any point in the assembly and the chimney assembly shall not include more than four elbows.

  R1005.8 Insulation shield. Where factory-built chimneys pass through insulated assemblies, an insulation shield constructed of steel having a thickness of not less than 0.0187 inch (0.4712 mm) (No. 26 gage) shall be installed to provide clearance between the chimney and the insulation material. The clearance shall be not less than the clearance to combustibles specified by the chimney manufacturer’s installation instructions. Where chimneys pass through attic space, the shield shall terminate not less than 2 inches (51 mm) above the insulation materials and shall be secured in place to prevent displacement. Insulation shields provided as part of a listed chimney system shall be installed in accordance with the manufacturer’s installation instructions.

  R1005.9 Factory-built chimney offsets. Where a fireplace manufacturer’s instructions do not address factory-built chimney offsets, no part of the chimney shall be at an angle of more than 30 degrees (0.52 rad) from vertical at any point in the assembly and the chimney assembly shall not include more than four elbows.

  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

  10-12 2025 CALIFORNIA RESIDENTIAL CODE

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

  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.

• CRC § 14.3 Medium relevance — show source text

  2111 A .14.3 Exterior air intake. The exterior air intake shall be capable of providing all combustion air from the exterior of the dwelling. The exterior air intake shall not be located within a garage, attic, basement or crawl space of the dwelling nor shall the air intake 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.

  2111 A .14.4 Clearance. Unlisted combustion 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. 2111 A .14.5 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 or for fireplaces tested for emissions shall be constructed according to the fireplace manufacturer’s instructions.

  2111 A .14.6 Outlet. The exterior air outlet is permitted to be located in the back or sides of the firebox chamber or within 24 inches (610 mm) of the firebox opening on or near the floor. The outlet shall be closable and designed to prevent burning material from dropping into concealed combustible spaces.

  SECTION 2112 A —MASONRY HEATERS

  2112 A .1 Definition. A masonry heater is a heating appliance constructed of concrete or solid masonry, hereinafter referred to as “masonry,” which is designed to absorb and store heat from a solid fuel fire built in the firebox by routing the exhaust gases through internal heat exchange channels in which the flow path downstream of the firebox includes flow in either a horizontal or downward direction before entering the chimney and which delivers heat by radiation from the masonry surface of the heater.

  2112 A .2 Installation. Masonry heaters shall be installed in accordance with this section and comply with one of the following:

  1. Masonry heaters shall comply with the requirements of ASTM E1602.
  2. Masonry heaters shall be listed and labeled in accordance with UL 1482 or EN 15250 and installed in accordance with the manufacturer’s instructions.

  2112 A .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 2113 A .2.

  2112 A .4 Seismic reinforcing. In structures assigned to Seismic Design Category D, E or F, masonry heaters shall be anchored to the masonry foundation in accordance with Section 2113 A .3. Seismic reinforcing shall not be required within the body of a masonry heater with a height that 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 2113 A .

• CRC § 25.4 Medium relevance — show source text

  WOOD MANTEL

  MASONRY COMBUSTIBL EDGE ABUTTI 12″ MIN FROM 2″ CLEAR TO COMB FRAME W	COMBUSTIBL EDGE ABUTTI 12″ MIN FROM 2″ CLEAR TO COMB	Col3
  COMBUSTIBL EDGE ABUTTI 12″ MIN FROM MASONRY 2″ CLEAR TO COMB FRAME W

  For SI: 1 inch = 25.4 mm

  2111 A .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 A .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 A .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.

  21A-12 2025 CALIFORNIA BUILDING CODE

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

  MASONRY

  2111 A .14.2 Masonry fireplaces. Listed combustion air ducts for masonry fireplaces shall be installed according to the terms of their listing and manufacturer’s instructions.

  2111 A .14.3 Exterior air intake. The exterior air intake shall be capable of providing all combustion air from the exterior of the dwelling. The exterior air intake shall not be located within a garage, attic, basement or crawl space of the dwelling nor shall the air intake 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.

  2111 A .14.4 Clearance. Unlisted combustion 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. 2111 A .14.5 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 or for fireplaces tested for emissions shall be constructed according to the fireplace manufacturer’s instructions.

  2111 A .14.6 Outlet. The exterior air outlet is permitted to be located in the back or sides of the firebox chamber or within 24 inches (610 mm) of the firebox opening on or near the floor. The outlet shall be closable and designed to prevent burning material from dropping into concealed combustible spaces.

  SECTION 2112 A —MASONRY HEATERS

• CRC § 9-4 Medium 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 § 2111.14.2 Medium relevance — show source text

  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
  MASONRY
  2″ CLEAR
  TO COMB
  FRAME W
  WOOD MANT|||

  2111.14.2 Masonry fireplaces. Listed combustion air ducts for masonry fireplaces shall be installed according to the terms of their listing and manufacturer’s instructions.

  2111.14.3 Exterior air intake. The exterior air intake shall be capable of providing all combustion air from the exterior of the dwelling. The exterior air intake shall not be located within a garage, attic, basement or crawl space of the dwelling nor shall the air intake 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.

  2111.14.4 Clearance. Unlisted combustion 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. 2111.14.5 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 or for fireplaces tested for emissions shall be constructed according to the fireplace manufacturer’s instructions.

  2111.14.6 Outlet. The exterior air outlet is permitted to be located in the back or sides of the firebox chamber or within 24 inches (610 mm) of the firebox opening on or near the floor. The outlet shall be closable and designed to prevent burning material from dropping into concealed combustible spaces.

  SECTION 2112—MASONRY HEATERS

  2112.1 Definition. A masonry heater is a heating appliance constructed of concrete or solid masonry, hereinafter referred to as “masonry,” which is designed to absorb and store heat from a solid fuel fire built in the firebox by routing the exhaust gases through internal heat exchange channels in which the flow path downstream of the firebox includes flow in either a horizontal or downward direction before entering the chimney and which delivers heat by radiation from the masonry surface of the heater.

  2112.2 Installation. Masonry heaters shall be installed in accordance with this section and comply with one of the following:

  1. Masonry heaters shall comply with the requirements of ASTM E1602.
  2. Masonry heaters shall be listed and labeled in accordance with UL 1482 or EN 15250 and installed in accordance with the manufacturer’s instructions.

  2112.3 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 2113.2.

  2112.4 Seismic reinforcing. In structures assigned to Seismic Design Category D, E or F, masonry heaters shall be anchored to the masonry foundation in accordance with Section 2113.3. Seismic reinforcing shall not be required within the body of a masonry heater with a height that is equal to or less than 3.5 times its body width and where the masonry chimney serving the heater is not

• CRC § 25.4 Medium relevance — show source text

  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. 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 MASONRY 2″ CLEAR TO COMB FRAME W WOOD MANT

  2111.14.2 Masonry fireplaces. Listed combustion air ducts for masonry fireplaces shall be installed according to the terms of their listing and manufacturer’s instructions.

  2111.14.3 Exterior air intake. The exterior air intake shall be capable of providing all combustion air from the exterior of the dwelling. The exterior air intake shall not be located within a garage, attic, basement or crawl space of the dwelling nor shall the air intake 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.

  2111.14.4 Clearance. Unlisted combustion 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. 2111.14.5 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 or for fireplaces tested for emissions shall be constructed according to the fireplace manufacturer’s instructions.

• CRC § 2025 Medium 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.

• California Residential Code Medium relevance — show source text

  ** Firepl
  ories. Listed
  r’s instructio
  onry heater
  
  WOO||a
  a
  n
  is
  
  |c
  n
  s.
  a
  
  D|e f
  d
  F
  
  
  M|ir
  la
  ir
  he
  
  A|e
  b
  e
  S
  a
  
  N|bl
  e
  pl
  E
  ti
  
  T|o
  le
  a
  C
  n
  
  E|c
  d
  ce
  TI
  g
  
  L|ki
  f
  
  O
  a
  
  |n
  ir
  ac
  N
  p
  |g
  ep
  c
  
  pl
  |||||||||||||| |cking. Firepl
  ories. Listed
  r’s instructio
  onry heater
  
  WOO||a
  a
  n
  is
  
  |c
  n
  s.
  a
  
  D|e f
  d
  F
  
  
  M|ir
  la
  ir
  he
  
  A|e
  b
  e
  S
  a
  
  N|bl
  e
  pl
  E
  ti
  
  T|o
  le
  a
  C
  n
  
  E|c
  d
  ce
  TI
  g
  
  L|ki
  f
  
  O
  a
  
  |n
  ir
  ac
  N
  p
  |g
  ep
  c
  
  pl
  |sh
  l
  e
  R1
  ia
  |a
  ac
  ss
  0
  n
  |ll
  e
  o
  0
  c
  |co
  a
  rie
  2
  e c
  |co
  a
  rie
  2
  e c
  |co
  a
  rie
  2
  e c
  |co
  a
  rie
  2
  e c
  |co
  a
  rie
  2
  e c
  |co
  a
  rie
  2
  e c
  |co
  a
  rie
  2
  e c
  |co
  a
  rie
  2
  e c
  |co
  a
  rie
  2
  e c
  |co
  a
  rie
  2
  e c
  |

  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:

  1. Masonry heaters shall comply with the requirements of ASTM E1602.
  2. Masonry heaters shall be listed and labeled in accordance with UL 1482 or CEN 15250 and installed in accordance with the manufacturer’s instructions.
• CRC § 10-6 Medium 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:

  1. Masonry heaters shall comply with the requirements of ASTM E1602.
  2. 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:

  1. 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.
  2. 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 Medium 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 § 2112.1 Medium relevance — show source text

  SECTION 2112—MASONRY HEATERS

  2112.1 Definition. A masonry heater is a heating appliance constructed of concrete or solid masonry, hereinafter referred to as “masonry,” which is designed to absorb and store heat from a solid fuel fire built in the firebox by routing the exhaust gases through internal heat exchange channels in which the flow path downstream of the firebox includes flow in either a horizontal or downward direction before entering the chimney and which delivers heat by radiation from the masonry surface of the heater.

  2112.2 Installation. Masonry heaters shall be installed in accordance with this section and comply with one of the following:

  1. Masonry heaters shall comply with the requirements of ASTM E1602.
  2. Masonry heaters shall be listed and labeled in accordance with UL 1482 or EN 15250 and installed in accordance with the manufacturer’s instructions.

  2112.3 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 2113.2.

  2112.4 Seismic reinforcing. In structures assigned to Seismic Design Category D, E or F, masonry heaters shall be anchored to the masonry foundation in accordance with Section 2113.3. Seismic reinforcing shall not be required within the body of a masonry heater with a height that is equal to or less than 3.5 times its body width and where the masonry chimney serving the heater is not

  2025 CALIFORNIA BUILDING CODE 21-13

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

  MASONRY

  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 2113.

  2112.5 Masonry heater clearance. Combustible materials shall not be placed within 36 inches (914 mm) or the distance of the allowed reduction method from the outside surface of a masonry heater in accordance with NFPA 211, Section 12.6, 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:

  1. Where the masonry heater wall thickness is not less than 8 inches (203 mm) of solid masonry and the wall thickness of the heat exchange channels is not less than 5 inches (127 mm) 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.
  2. Masonry heaters listed and labeled in accordance with UL 1482 or EN 15250 and installed in accordance with the manufacturer’s instructions.

  SECTION 2113—MASONRY CHIMNEYS

  2113.1 General. The construction of masonry chimneys consisting of solid masonry units, hollow masonry units grouted solid, stone or concrete shall be in accordance with this section.