CRC · California Residential Code

How high must a chimney extend and what are the rules for caps, rain caps and spark arrestors?

Homes must have chimneys that extend at least **2 ft above any roof surface within 10 ft** and at least **3 ft above the roof penetration** (CRC **§ R1003.9**). Masonry chimneys need a sloped concrete/metal/stone **cap** with drip edge (**§ R1003.9.1**). Chimneys serving solid‑fuel appliances must have an approved **spark arrestor** whose mesh, opening size and **net free area (≥4× the flue outlet)** meet the CRC requirements; **rain caps** must also provide ≥4× net free area (**§ R1003.9.2–R1003.9.3**). Always size caps/screens for net free area, use the specified mesh/gauge, and provide removable access for cleaning.

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Last reviewed: July 6, 2026

What the code requires — 2–4 sentences

In plain English: a chimney must extend high enough to keep smoke and products of combustion away from nearby roof surfaces — specifically at least 2 feet (610 mm) higher than any portion of a building within 10 feet (3048 mm), and at least 3 feet (914 mm) above the highest point where the chimney passes through the roof. This is the termination rule in § R1003.9. Masonry chimneys must also have a sloped chimney cap and drip edge (§ R1003.9.1), chimneys serving solid‑fuel appliances must have an approved spark arrestor with specified mesh/opening and area requirements (§ R1003.9.2), and any masonry/metal rain cap must provide adequate net free area (§ R1003.9.3) .

The single most important rule: make the chimney at least 2 ft taller than any roof surface within 10 ft, but always ensure it is no less than 3 ft above the roof penetration — follow § R1003.9.

Requirements in detail

Termination height (how high the chimney must extend)

  • Required minimums:
    • Minimum: 2 feet (610 mm) higher than any portion of the building within a 10‑foot (3048 mm) horizontal radius. See § R1003.9.
    • Absolute minimum: 3 feet (914 mm) above the highest point where the chimney passes through the roof. See § R1003.9.
  • Practical note: both conditions apply — the chimney must meet whichever produces the greater required height at the termination point.

Decision‑relevant dimensions/values

Item Required value / test Code Reference
Horizontal measurement for the 2 ft rule 10 ft (3048 mm) horizontally from chimney § R1003.9
Vertical clearance for nearby roof surfaces 2 ft (610 mm) above any portion of building within 10 ft § R1003.9
Minimum height above penetration 3 ft (914 mm) above highest point where chimney passes through roof § R1003.9
Chimney cap material and features (masonry chimneys) Concrete, metal or stone cap; sloped to shed water, drip edge, caulked bond break around flue liners per ASTM C1283 § R1003.9.1
Spark arrestor — net free area ≥ 4 × net free area of the chimney flue outlet § R1003.9.2
Spark arrestor — screen resistance Equivalent to 12‑gage wire, 19‑gage galvanized or 24‑gage stainless § R1003.9.2
Spark arrestor — opening size Shall NOT permit passage of spheres > 1/2 in (12.7 mm) and shall NOT block spheres < 3/8 in (9.5 mm) § R1003.9.2
Rain cap — net free area ≥ 4 × net free area of the chimney flue outlet (for masonry or metal rain caps on masonry chimneys) § R1003.9.3
Cleaning access Spark arrestor/screen or cap shall be removable to allow cleaning; spark arrestor shall be accessible for cleaning § R1003.9.2

Chimney caps (§ R1003.9.1)

  • Applies to masonry chimneys: required to have a concrete, metal or stone cap, a drip edge, and a caulked bond break around any flue liners in accordance with ASTM C1283. The cap must be sloped to shed water. See § R1003.9.1 .
  • The code text addresses masonry caps specifically; if you are using a factory‑built or non‑masonry chimney, follow the product listing and manufacturer instructions and relevant CRC/CMC provisions.

Spark arrestors (§ R1003.9.2)

  • Required when the chimney is attached to any appliance or fireplace that burns solid fuel (wood, coal, pellets, etc.) — all such chimneys must have an approved spark arrestor. See § R1003.9.2 .
  • Key dimensional / construction requirements:
    • Net free area of the arrestor: not less than four times the net free area of the flue outlet. § R1003.9.2
    • Screen material / heat & corrosion resistance: equivalent to 12‑gage wire, 19‑gage galvanized steel, or 24‑gage stainless steel. § R1003.9.2
    • Opening size: must not permit spheres > 1/2 in (12.7 mm) to pass, and must not block spheres < 3/8 in (9.5 mm). § R1003.9.2
    • Access: the arrestor and screen or cap must be removable and provide access for cleaning the flue. § R1003.9.2

Rain caps (§ R1003.9.3)

  • When a masonry or metal rain cap is installed on a masonry chimney, the net free area under the cap must be not less than four times the net free area of the outlet of the chimney flue it serves. See § R1003.9.3 .

Exceptions & special cases

  • The code text explicitly limits the spark arrestor requirement to chimneys attached to appliances or fireplaces that burn solid fuel — if the appliance uses gas only and is listed with factory venting, the spark arrestor requirement of § R1003.9.2 does not apply as written (use appliance/manufacturer and California Mechanical Code guidance for gas vents). See § R1003.9.2 .
  • The chimney cap requirements in § R1003.9.1 are stated for masonry chimneys; factory‑built chimneys and other systems are governed by their listing/manufacturer instructions and other CRC/CMC sections (see flue lining and factory‑built chimney rules). See § R1003.9.1 and related sections.
  • No additional exceptions to the termination height (§ R1003.9) are provided in the cited sections; the two‑foot/ten‑foot and three‑foot rules are the controlling limits.
  • If a code provision you need is not present in the retrieved text (for example, appliance‑specific venting details), consult the California Mechanical Code or the appliance listing; those areas are outside the four cited CRC sections above. The CRC text does reference the California Mechanical Code for appliance venting requirements.

Common mistakes

  • Measuring the wrong distance: people often measure the 2‑ft clearance to the nearest roof plane instead of any portion of the building within 10 ft horizontally. Always check the highest nearby roof/massing within 10 ft horizontally. See § R1003.9.
  • Forgetting the 3‑ft roof‑penetration minimum: even if the 2‑ft/10‑ft rule would allow a lower height, the chimney still must be at least 3 ft above the highest point where it passes through the roof. See § R1003.9.
  • Using the wrong mesh/gauge for spark arrestors or rain caps (or failing the net‑free‑area calculation). The code requires mesh and net free‑area criteria — check § R1003.9.2 and § R1003.9.3.
  • Installing caps or screens that are not removable or that obstruct cleaning access; the code requires access for cleaning. See § R1003.9.2.

Worked example — concrete scenario

Scenario: A masonry fireplace chimney penetrates a roof. The highest point of the roof within a 10‑ft horizontal radius is a ridge that is 8 ft horizontally from the chimney termination and is 1.5 ft higher than the chimney's current top; the chimney passes through the roof at a flashing point that is 2 ft lower than the ridge. Determine required termination.

Step 1 — Apply the 2‑ft / 10‑ft rule (§ R1003.9): Because the ridge (a portion of the building) is within 10 ft, the chimney top must be at least 2 ft higher than that ridge. That means the chimney top must be raised by 1.5 ft (difference to ridge) + 2 ft = 3.5 ft above the current chimney top level measured to the ridge level. See § R1003.9.

Step 2 — Apply the 3‑ft above penetration rule (§ R1003.9): The chimney must also be at least 3 ft above the highest point where it passes through the roof (the flashing point). If that flashing point is 2 ft lower than the ridge, then the chimney must be 3 ft above the flashing. Compare which required top is higher:

  • Requirement from Step 1: chimney top must be 3.5 ft higher than current top relative to ridge — this produces a termination height that is greater than the 3 ft above flashing requirement (because the ridge is higher).
  • Therefore the controlling requirement is the 2 ft above the portion within 10 ft, and you must construct the termination to meet that — satisfying § R1003.9.

Also check cap/spark arrestor/rain cap sizing: compute the chimney flue outlet net free area and ensure any arrestor or rain cap has ≥ 4× that area and that mesh/openings and material meet the sizes/gage listed in § R1003.9.2 and § R1003.9.3. Ensure the cap is sloped and includes the drip edge/caulked bond break per § R1003.9.1.

Related provisions (CRC)

  • § R1003.11 — Flue lining requirements for masonry chimneys (lining material, appliance compatibility).
  • § R1003.17 — Chimney cleanouts (location and access) — see the masonry chimney cleanout provisions in Chapter 10 index.
  • § R1003.18 — Clearance from combustibles (chimney clearances are referenced in the index).
  • § R1003.5 — Corbeling limits (chimney projection and corbeling rules).
  • Relevant cross‑codes: California Mechanical Code and California Building Code contain additional chimney, venting, and spark‑arrestor provisions that may apply to factory‑built systems or appliance connections. The CRC text references the Mechanical Code for appliance venting requirements.

Code references

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

  • CRC § 9.1 High relevance — show source text

    R1003.9 Termination. Chimneys shall extend not less than 2 feet (610 mm) higher than any portion of a building within 10 feet (3048 mm), but shall be not less than 3 feet (914 mm) above the highest point where the chimney passes through the roof.

    R1003.9.1 Chimney caps. Masonry chimneys shall have a concrete, metal or stone cap, a drip edge and a caulked bond break around any flue liners in accordance with ASTM C1283. The concrete, metal or stone cap shall be sloped to shed water.

    R1003.9.2 Spark arrestors. All chimneys attached to any appliance or fireplace that burns solid fuel shall be equipped with an approved spark arrester. Where a spark arrestor is installed on a masonry chimney, the spark arrestor shall meet all of the following requirements:

    1. The net free area of the arrestor shall be not less than four times the net free area of the outlet of the chimney flue it

    serves.

    1. The arrestor screen shall have heat and corrosion resistance equivalent to 12 gage wire, 19-gage galvanized steel or 24gage stainless steel.
    2. Openings shall not permit the passage of spheres having a diameter greater than [1] / 2 inch (12.7 mm) nor block the passage of spheres having a diameter less than [3] / 8 inch (9.5 mm).
    3. The spark arrestor shall be located with access for cleaning and the screen or chimney cap shall be removable to allow for cleaning of the chimney flue.

    R1003.9.3 Rain caps. Where a masonry or metal rain cap is installed on a masonry chimney, the net free area under the cap shall be not less than four times the net free area of the outlet of the chimney flue it serves.

    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:

    1. Clay flue lining complying with the requirements of ASTM C315.
    2. Listed and labeled chimney lining systems complying with UL 1777.
    3. Factory-built chimneys or chimney units listed for installation within masonry chimneys.
    4. 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.

  • CRC § 2113.6 High relevance — show source text

    2113.6 Changes in dimension. The chimney wall or chimney flue lining shall not change in size or shape within 6 inches (152 mm) above or below where the chimney passes through floor components, ceiling components or roof components.

    2113.7 Offsets. Where a masonry chimney is constructed with a fireclay flue liner surrounded by one wythe of masonry, the maximum offset shall be such that the centerline of the flue above the offset does not extend beyond the center of the chimney wall below the offset. Where the chimney offset is supported by masonry below the offset in an approved manner, the maximum offset limitations shall not apply. Each individual corbeled masonry course of the offset shall not exceed the projection limitations specified in Section 2113.5.

    2113.8 Additional load. Chimneys shall not support loads other than their own weight unless they are designed and constructed to support the additional load. Masonry chimneys are permitted to be constructed as part of the masonry walls or concrete walls of the building.

    2113.9 Termination. Chimneys shall extend not less than 2 feet (610 mm) higher than any portion of the building within 10 feet (3048 mm), but shall be not less than 3 feet (914 mm) above the highest point where the chimney passes through the roof.

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    MASONRY

    2113.9.1 Chimney caps. Masonry chimneys shall have a concrete, metal or stone cap, sloped to shed water, a drip edge and a caulked bond break around any flue liners in accordance with ASTM C1283.

    2113.9.2 Spark arrestors. [SFM] All chimneys attached to any appliance or fireplace that burns solid fuel shall be equipped with an approved spark arrester. The spark arrestor shall meet all of the following requirements:

    1. The net free area of the spark arrestor shall not be less than four times the net free area of the outlet of the chimney.
    2. The spark arrestor screen shall have heat and corrosion resistance equivalent to 12-gage wire, 19-gage galvanized steel or 24-gage stainless steel.
    3. Openings shall not permit the passage of spheres having a diameter greater than [1] / 2 inch (13 mm) nor block the passage of spheres having a diameter less than [3] / 8 inch (9.5 mm).
    4. The spark arrestor shall be accessible for cleaning and the screen or chimney cap shall be removable to allow for cleaning of the chimney flue.

    2113.9.3 Rain caps. Where a masonry or metal rain cap is installed on a masonry chimney, the net free area under the cap shall be not less than four times the net free area of the outlet of the chimney flue it serves.

    2113.10 Wall thickness. Masonry chimney walls shall be constructed of concrete, solid masonry units or hollow masonry units grouted solid with not less than 4 inches (102 mm) nominal thickness.

    2113.10.1 Masonry veneer chimneys. Where masonry is used as veneer for a framed chimney, through flashing and weep holes shall be provided as required by Chapter 14.

  • CRC § 9.1 High relevance — show source text

    2113 A .7 Offsets. Where a masonry chimney is constructed with a fireclay flue liner surrounded by one wythe of masonry, the maximum offset shall be such that the centerline of the flue above the offset does not extend beyond the center of the chimney wall below the offset. Where the chimney offset is supported by masonry below the offset in an approved manner, the maximum offset limitations shall not apply. Each individual corbeled masonry course of the offset shall not exceed the projection limitations specified in Section 2113 A .5.

    2113 A .8 Additional load. Chimneys shall not support loads other than their own weight unless they are designed and constructed to support the additional load. Masonry chimneys are permitted to be constructed as part of the masonry walls or concrete walls of the building.

    2113 A .9 Termination. Chimneys shall extend not less than 2 feet (610 mm) higher than any portion of the building within 10 feet (3048 mm), but shall be not less than 3 feet (914 mm) above the highest point where the chimney passes through the roof.

    2113 A .9.1 Chimney caps. Masonry chimneys shall have a concrete, metal or stone cap, sloped to shed water, a drip edge and a caulked bond break around any flue liners in accordance with ASTM C1283.

    2113 A .9.2 Spark arrestors. [SFM] All chimneys attached to any appliance or fireplace that burns solid fuel shall be equipped with an approved spark arrester. The spark arrestor shall meet all of the following requirements:

    1. The net free area of the spark arrestor shall not be less than four times the net free area of the outlet of the chimney.
    2. The spark arrestor screen shall have heat and corrosion resistance equivalent to 12-gage wire, 19-gage galvanized steel or 24-gage stainless steel.
    3. Openings shall not permit the passage of spheres having a diameter greater than [1] / 2 inch (13 mm) nor block the passage of spheres having a diameter less than [3] / 8 inch (9.5 mm).
    4. The spark arrestor shall be accessible for cleaning and the screen or chimney cap shall be removable to allow for cleaning of the chimney flue.

    2113 A .9.3 Rain caps. Where a masonry or metal rain cap is installed on a masonry chimney, the net free area under the cap shall be not less than four times the net free area of the outlet of the chimney flue it serves.

    2113 A .10 Wall thickness. Masonry chimney walls shall be constructed of concrete, solid masonry units or hollow masonry units grouted solid with not less than 4 inches (102 mm) nominal thickness.

    2113 A .10.1 Masonry veneer chimneys. Where masonry is used as veneer for a framed chimney, through flashing and weep holes shall be provided as required by Chapter 14.

    2113 A .11 Flue lining (material). Masonry chimneys shall be lined. The lining material shall be appropriate for the type of appliance connected, according to the terms of the appliance listing and the manufacturer’s instructions.

  • CRC § 10-7 High relevance — show source text

    6 screws for each bolt.

    R1003.5 Corbeling. Masonry chimneys shall not be corbeled more than one-half of the chimney’s wall thickness from a wall or foundation, nor shall a chimney be corbeled from a wall or foundation that is less than 12 inches (305 mm) thick unless it projects equally on each side of the wall, except that on the second story of a two-story dwelling, corbeling of chimneys on the exterior of the enclosing walls shall be permitted to be equal to the wall thickness. The projection of a single course shall not exceed one-half the unit height or one-third of the unit bed depth, whichever is less.

    R1003.6 Changes in dimension. The chimney wall or chimney flue lining shall not change in size or shape within 6 inches (152 mm) above or below where the chimney passes through floor components, ceiling components or roof components.

    R1003.7 Offsets. Where a masonry chimney is constructed with a fireclay flue liner surrounded by one wythe of masonry, the maximum offset shall be such that the centerline of the flue above the offset does not extend beyond the center of the chimney wall below the offset. Where the chimney offset is supported by masonry below the offset in an approved manner, the maximum offset limitations shall not apply. Each individual corbeled masonry course of the offset shall not exceed the projection limitations specified in Section R1003.5.

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    CHIMNEYS AND FIREPLACES

    R1003.8 Additional load. Chimneys shall not support loads other than their own weight unless they are designed and constructed to support the additional load. Construction of masonry chimneys as part of the masonry walls or reinforced concrete walls of the building shall be permitted.

    R1003.9 Termination. Chimneys shall extend not less than 2 feet (610 mm) higher than any portion of a building within 10 feet (3048 mm), but shall be not less than 3 feet (914 mm) above the highest point where the chimney passes through the roof.

    R1003.9.1 Chimney caps. Masonry chimneys shall have a concrete, metal or stone cap, a drip edge and a caulked bond break around any flue liners in accordance with ASTM C1283. The concrete, metal or stone cap shall be sloped to shed water.

    R1003.9.2 Spark arrestors. All chimneys attached to any appliance or fireplace that burns solid fuel shall be equipped with an approved spark arrester. Where a spark arrestor is installed on a masonry chimney, the spark arrestor shall meet all of the following requirements:

    1. The net free area of the arrestor shall be not less than four times the net free area of the outlet of the chimney flue it

    serves.

    1. The arrestor screen shall have heat and corrosion resistance equivalent to 12 gage wire, 19-gage galvanized steel or 24gage stainless steel.
    2. Openings shall not permit the passage of spheres having a diameter greater than [1] / 2 inch (12.7 mm) nor block the passage of spheres having a diameter less than [3] / 8 inch (9.5 mm).
    3. The spark arrestor shall be located with access for cleaning and the screen or chimney cap shall be removable to allow for cleaning of the chimney flue.
  • CRC § 9.5 High relevance — show source text

    The net free area of the spark arrestor shall not be less than four times the net free area of the outlet of the chimney. 2. The spark arrestor screen shall have heat and corrosion resistance equivalent to 12-gage wire, 19-gage galvanized steel or 24-gage stainless steel. 3. Openings shall not permit the passage of spheres having a diameter greater than [1] / 2 inch (13 mm) nor block the passage of spheres having a diameter less than [3] / 8 inch (9.5 mm). 4. The spark arrestor shall be accessible for cleaning and the screen or chimney cap shall be removable to allow for cleaning of the chimney flue.

    2113 A .9.3 Rain caps. Where a masonry or metal rain cap is installed on a masonry chimney, the net free area under the cap shall be not less than four times the net free area of the outlet of the chimney flue it serves.

    2113 A .10 Wall thickness. Masonry chimney walls shall be constructed of concrete, solid masonry units or hollow masonry units grouted solid with not less than 4 inches (102 mm) nominal thickness.

    2113 A .10.1 Masonry veneer chimneys. Where masonry is used as veneer for a framed chimney, through flashing and weep holes shall be provided as required by Chapter 14.

    2113 A .11 Flue lining (material). Masonry chimneys shall be lined. The lining material shall be appropriate for the type of appliance connected, according to the terms of the appliance listing and the manufacturer’s instructions.

    2113 A .11.1 Residential-type appliances (general). Flue lining systems shall comply with one of the following:

    1. Clay flue lining complying with the requirements of ASTM C315.
    2. Listed chimney lining systems complying with UL 1777.
    3. Factory-built chimneys or chimney units listed for installation within masonry chimneys.
    4. 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).

    2113 A .11.1.1 Flue linings for specific appliances. Flue linings other than those covered in Section 2113 A .11.1 intended for use with specific appliances shall comply with Sections 2113 A .11.1.2 through 2113 A .11.1.4, 2113 A .11.2 and 2113 A .11.3.

    2113 A .11.1.2 Gas appliances. Flue lining systems for gas appliances shall be in accordance with the California Mechanical Code .

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    MASONRY

    2113 A .11.1.3 Pellet fuel-burning appliances. Flue lining and vent systems for use in masonry chimneys with pellet fuel-burning appliances shall be limited to flue lining systems complying with Section 2113 A .11.1 and pellet vents listed for installation within masonry chimneys (see Section 2113 A .11.1.5 for marking).

  • CRC § 2113.9.2 High relevance — show source text

    2113.9.2 Spark arrestors. [SFM] All chimneys attached to any appliance or fireplace that burns solid fuel shall be equipped with an approved spark arrester. The spark arrestor shall meet all of the following requirements:

    1. The net free area of the spark arrestor shall not be less than four times the net free area of the outlet of the chimney.
    2. The spark arrestor screen shall have heat and corrosion resistance equivalent to 12-gage wire, 19-gage galvanized steel or 24-gage stainless steel.
    3. Openings shall not permit the passage of spheres having a diameter greater than [1] / 2 inch (13 mm) nor block the passage of spheres having a diameter less than [3] / 8 inch (9.5 mm).
    4. The spark arrestor shall be accessible for cleaning and the screen or chimney cap shall be removable to allow for cleaning of the chimney flue.

    2113.9.3 Rain caps. Where a masonry or metal rain cap is installed on a masonry chimney, the net free area under the cap shall be not less than four times the net free area of the outlet of the chimney flue it serves.

    2113.10 Wall thickness. Masonry chimney walls shall be constructed of concrete, solid masonry units or hollow masonry units grouted solid with not less than 4 inches (102 mm) nominal thickness.

    2113.10.1 Masonry veneer chimneys. Where masonry is used as veneer for a framed chimney, through flashing and weep holes shall be provided as required by Chapter 14.

    2113.11 Flue lining (material). Masonry chimneys shall be lined. The lining material shall be appropriate for the type of appliance connected, according to the terms of the appliance listing and the manufacturer’s instructions.

    2113.11.1 Residential-type appliances (general). Flue lining systems shall comply with one of the following:

    1. Clay flue lining complying with the requirements of ASTM C315.
    2. Listed chimney lining systems complying with UL 1777.
    3. Factory-built chimneys or chimney units listed for installation within masonry chimneys.
    4. 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).

    2113.11.1.1 Flue linings for specific appliances. Flue linings other than those covered in Section 2113.11.1 intended for use with specific appliances shall comply with Sections 2113.11.1.2 through 2113.11.1.4, 2113.11.2 and 2113.11.3.

    2113.11.1.2 Gas appliances. Flue lining systems for gas appliances shall be in accordance with the California Mechanical Code .

    2113.11.1.3 Pellet fuel-burning appliances. Flue lining and vent systems for use in masonry chimneys with pellet fuel-burning appliances shall be limited to flue lining systems complying with Section 2113.11.1 and pellet vents listed for installation within masonry chimneys (see Section 2113.11.1.5 for marking).

  • CRC § 9.1 High relevance — show source text

    Defined R202 Chimneys Caps R1003.9.1 Clearance R1003.18 Corbeling R1003.5 Crickets R1003.20 Design (masonry) R1003.1 Factory-built R1005 Fireblocking R1003.19 Fireplaces Chapter 10 Flue area R1003.14, R1003.15 Flue lining R1003.11 Load R1003.8 Multiple flue R1003.14 Rain caps R1003.9.3 Spark arrestors R1003.9.2 Termination R1003.9

    Wall thickness R1003.10

    Clay Tiles R905.3

    Cleanout Masonry chimney R1003.17 Climate Types R301.2 Climate Zones R202, R702.7.3, Table R702.7(5) Columns R407

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    INDEX

    Live load R301.5

    Nominal sizes R301.8

    Roof load R301.6

    Seismic R301.2.2

    Snow loads R301.2.3 Story height R301.3 Sunrooms R301.2.1.1.1

    Wind R301.2.1

    Doors

    Egress R318.2 Exterior R318.3, R609 Glazing R324 Draftstopping R302.12, R502.13 Drainage Foundation R405 Site drainage R300 Ducts

    Defined R202 Dwelling-garage wall and ceiling penetration R302.5.2 System, definition R202 Dwelling Unit Separation R302.2, R302.3 Sprinklers (see Automatic Sprinkler System)

    Electric Vehicle Charging Stations R317.6 Elevator R323.1, R323.3 Emergency Escape and Rescue Openings R319

    Additions R319.6

    Area wells R319.4 Bars, grilles, covers and screens R319.4.4

    Basements, existing R319.7 Dimensions R319.2

    Doors R319.3

    Replacement window R319.5 Under decks and porches R319.2.4 Where required R319.1 Window fall protection R321.2 Emergency Housing Appendix CJ Energy Storage Systems R328 ESS vehicle impact protection Figure R330.8.1 Maximum aggregate ratings of ESS Table R330.5 Protection from impact R330.8 Toxic and highly toxic gas R330.12 Entry 1.8.5, R104.4 Existing Buildings Appendix BO Administrative R101.2, R102.6, R105.1, R105.8, R106.2, R113.1, R113.2 Basements R313.1.2, R319.7 Carbon monoxide alarms R311.2.2, R311.5, R311.6 Flood R104.3.1

  • 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

  • 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 § 28-1 Medium relevance — show source text

    2025 CALIFORNIA BUILDING CODE 28-1

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

    28-2 2025 CALIFORNIA BUILDING CODE

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    28 MECHANICAL SYSTEMS

    User notes:

    About this chapter: Mechanical systems are a key element of any building. Chapter 28 regulates such systems by linking to the California Mechanical Code and California Plumbing Code, where details of mechanical system requirements are provided.

    SECTION 2801—GENERAL

    [M] 2801.1 Scope. The provisions of this chapter, the California Mechanical Code and the California Plumbing Code shall govern the design, construction, erection and installation of mechanical appliances, equipment and systems used in buildings and structures covered by this code. Masonry chimneys, fireplaces and barbecues shall comply with the California Mechanical Code and Chapter 21 of this code. The California Fire Code, the International Property Maintenance Code, the California Mechanical Code and the California Plumbing Code shall govern the use and maintenance of mechanical components, appliances, equipment and systems. The Califor- nia Existing Building Code, the California Mechanical Code and the California Plumbing Code shall govern the alteration, repair, relocation, replacement and addition of mechanical components, appliances, equipment and systems.

    SECTION 2802—SPARK ARRESTOR [SFM]

    2802.1 Spark arrestor. [SFM] All chimneys attached to any appliance or fireplace that burns solid fuel shall be equipped with an approved spark arrester. The spark arrestor shall meet all of the following requirements: 1. The net free area of the spark arrestor shall be not less than four times the net free area of the outlet of the chimney. 2. The spark arrestor screen shall have heat and corrosion resistance equivalent to 19-gage galvanized steel or 24-gage stainless steel.

    3. Openings shall not permit the passage of spheres having a diameter larger than [1] / 2 inch (12.7 mm) nor block the passage of spheres having a diameter of less than [3] / 8 inch (9.5 mm). 4. The spark arrestor shall be accessible for cleaning and the screen or chimney cap shall be removable to allow for cleaning of the chimney flue.

    2025 CALIFORNIA BUILDING CODE 28-3

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    28-4 2025 CALIFORNIA BUILDING CODE

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    29 PLUMBING SYSTEMS

    (Not Adopted By The State Of California) Refer To California Plumbing Code, Title 24, Part 5

    2025 CALIFORNIA BUILDING CODE 29-1

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    29-2 2025 CALIFORNIA BUILDING CODE

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    CALIFORNIA BUILDING CODE – MATRIX ADOPTION TABLE

  • CRC § 1.2 Medium relevance — show source text

    Room, minimum R312 Sleeping lofts R315.1, R315.2, R315.4 Area Wells R319.4

    INDEX

    Attic

    Access R807

    Habitable R316 Height R313.1.2 Ventilation R806 Automatic Sprinkler Systems R101.2, R309 Automotive Lifts R317.7

    Backfill

    Placement R404.1.7, R404.2.3, R404.2.4, R406.3.3, R406.3.4

    Basements

    Alterations R319.7 Ceiling height R313 Egress R318.4 Emergency escape and rescue openings R319.6 Bathroom R313.1, R326, R327 Exhaust fan R325.2.1

    Bathtub R326.1, R327 Enclosure R324.3.1, R324.4.5, R325.2 Finish R327.2 Space required R327.1 Board of Appeals (see Means of Appeal) Building Official Duties and powers R104 Built-Up Roofing (see Roofing)

    Carbon Monoxide Alarms R311

    Care Facilities R101.2, R322.3 Carports R317.2, R317.3 Ceiling Finishes R302.9, R805 Height R313 Certificate of Occupancy R110 Change of Occupancy R110.1 Emergency escape and rescue openings R319.5, R319.7.1 Chases R606.8

    Child Care

    Defined R202 Chimneys Caps R1003.9.1 Clearance R1003.18 Corbeling R1003.5 Crickets R1003.20 Design (masonry) R1003.1 Factory-built R1005 Fireblocking R1003.19 Fireplaces Chapter 10 Flue area R1003.14, R1003.15 Flue lining R1003.11 Load R1003.8 Multiple flue R1003.14 Rain caps R1003.9.3 Spark arrestors R1003.9.2 Termination R1003.9

    Wall thickness R1003.10

    Clay Tiles R905.3

    Cleanout Masonry chimney R1003.17 Climate Types R301.2 Climate Zones R202, R702.7.3, Table R702.7(5) Columns R407

    2025 CALIFORNIA RESIDENTIAL CODE INDEX-1

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

    INDEX

    Live load R301.5

    Nominal sizes R301.8

    Roof load R301.6

    Seismic R301.2.2

    Snow loads R301.2.3 Story height R301.3 Sunrooms R301.2.1.1.1

    Wind R301.2.1

    Doors

    Egress R318.2 Exterior R318.3, R609 Glazing R324 Draftstopping R302.12, R502.13 Drainage Foundation R405 Site drainage R300 Ducts

  • CRC § 4.8 Medium relevance — show source text

    2113 A .4 Seismic anchorage. Masonry chimneys and foundations shall be anchored at each floor, ceiling or roof line more than 6 feet (1829 mm) above grade with two [3] / 16 -inch by 1-inch (4.8 mm by 25 mm) straps 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 joists with two [1] / 2 -inch (12.7 mm) bolts.

    Exception: Seismic anchorage is not required for the following:

    1. In structures assigned to Seismic Design Category A or B.
    2. Where the masonry fireplace is constructed completely within the exterior walls.

    2113 A .5 Corbeling. Masonry chimneys shall not be corbeled more than half of the chimney’s wall thickness from a wall or foundation, nor shall a chimney be corbeled from a wall or foundation that is less than 12 inches (305 mm) in thickness unless it projects equally on each side of the wall, except that on the second story of a two-story dwelling, corbeling of chimneys on the exterior of the enclosing walls is permitted to equal the wall thickness. The projection of a single course shall not exceed one-half the unit height or one-third of the unit bed depth, whichever is less.

    2113 A .6 Changes in dimension. The chimney wall or chimney flue lining shall not change in size or shape within 6 inches (152 mm) above or below where the chimney passes through floor components, ceiling components or roof components.

    2113 A .7 Offsets. Where a masonry chimney is constructed with a fireclay flue liner surrounded by one wythe of masonry, the maximum offset shall be such that the centerline of the flue above the offset does not extend beyond the center of the chimney wall below the offset. Where the chimney offset is supported by masonry below the offset in an approved manner, the maximum offset limitations shall not apply. Each individual corbeled masonry course of the offset shall not exceed the projection limitations specified in Section 2113 A .5.

    2113 A .8 Additional load. Chimneys shall not support loads other than their own weight unless they are designed and constructed to support the additional load. Masonry chimneys are permitted to be constructed as part of the masonry walls or concrete walls of the building.

    2113 A .9 Termination. Chimneys shall extend not less than 2 feet (610 mm) higher than any portion of the building within 10 feet (3048 mm), but shall be not less than 3 feet (914 mm) above the highest point where the chimney passes through the roof.

    2113 A .9.1 Chimney caps. Masonry chimneys shall have a concrete, metal or stone cap, sloped to shed water, a drip edge and a caulked bond break around any flue liners in accordance with ASTM C1283.

    2113 A .9.2 Spark arrestors. [SFM] All chimneys attached to any appliance or fireplace that burns solid fuel shall be equipped with an approved spark arrester. The spark arrestor shall meet all of the following requirements: 1.

Frequently asked questions

Do these chimney height rules apply to factory‑built (metal) chimneys?

The termination height rule in § R1003.9 governs chimneys generally; masonry cap specifics in § R1003.9.1 are written for masonry chimneys. Factory‑built chimneys must follow the appliance listing/manufacturer instructions and applicable sections of the California Mechanical Code in addition to the termination rules.

Is a spark arrestor required on a gas fireplace chimney?

No — the code requires a spark arrestor only for chimneys attached to appliances or fireplaces that burn solid fuel (wood, coal, etc.). For gas appliances, follow the appliance listing and the California Mechanical Code. See § R1003.9.2.

How do I calculate "net free area" for a spark arrestor or rain cap?

Net free area is the open (air) area through the mesh or openings. The code requires the arrestor or cap net free area to be not less than 4 times the net free area of the flue outlet it serves (see § R1003.9.2 and § R1003.9.3). Measure the flue outlet area and size the cap/arrestor so its open area ≥ 4× that area.

Can I install a permanent screen that is not removable?

No — the spark arrestor screen or chimney cap must be removable (and the arrestor accessible) to allow cleaning of the chimney flue, per § R1003.9.2.

What mesh opening is required for a spark arrestor?

Openings shall not permit spheres larger than 1/2 inch (12.7 mm) and shall not block spheres smaller than 3/8 inch (9.5 mm); mesh must have equivalent heat/corrosion resistance to the required gauges (12‑gage wire / 19‑gage galvanized / 24‑gage stainless). See § R1003.9.2.

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California Residential Code