Exterior Walls

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

• CBC § 903.3.1.1 High relevance — show source text

  2. Fire walls shall be permitted to terminate at the interior surface of noncombustible exterior sheathing, exterior siding or other noncombustible exterior finishes provided that the sheathing, siding or other exterior noncombustible finish extends a horizontal distance of not less than 4 feet (1220 mm) on both sides of the fire wall.
  3. Fire walls shall be permitted to terminate at the interior surface of noncombustible exterior sheathing where the building on each side of the fire wall is protected by an automatic sprinkler system installed in accordance with Section 903.3.1.1 or 903.3.1.2.

  7-12 2025 CALIFORNIA BUILDING CODE

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

  FIRE AND SMOKE PROTECTION FEATURES

  706.5.1 Exterior walls. Where the fire wall intersects exterior walls, the fire-resistance rating and opening protection of the exterior walls shall comply with one of the following:

  1. The exterior walls on both sides of the fire wall shall have a 1-hour fire-resistance rating with [3] / 4 -hour protection where opening protection is required by Section 705.9. The fire-resistance rating of the exterior wall shall extend not less than 4 feet (1220 mm) on each side of the intersection of the fire wall to exterior wall. Exterior wall intersections at fire walls that form an angle equal to or greater than 180 degrees (3.14 rad) do not need exterior wall protection.
  2. Buildings or spaces on both sides of the intersecting fire wall shall assume to have an imaginary lot line at the fire wall and extending beyond the exterior of the fire wall. The location of the assumed line in relation to the exterior walls and the fire wall shall be such that the exterior wall and opening protection meet the requirements set forth in Sections 705.5 and 705.9. Such protection is not required for exterior walls terminating at fire walls that form an angle equal to or greater than 180 degrees (3.14 rad).

  706.5.2 Horizontal projecting elements. Fire walls shall extend to the outer edge of horizontal projecting elements such as balconies, roof overhangs, canopies, marquees and similar projections that are within 4 feet (1220 mm) of the fire wall.

  Exceptions:

  1. Horizontal projecting elements without concealed spaces, provided that the exterior wall behind and below the projecting element has not less than 1-hour fire-resistance-rated construction for a distance not less than the depth of the projecting element on both sides of the fire wall. Openings within such exterior walls shall be protected by opening protectives having a fire protection rating of not less than [3] / 4 hour.
  2. Noncombustible horizontal projecting elements with concealed spaces, provided that a minimum 1-hour fire-resistance-rated wall extends through the concealed space. The projecting element shall be separated from the building by not less than 1-hour fire-resistance-rated construction for a distance on each side of the fire wall equal to the depth of the projecting element. The wall is not required to extend under the projecting element where the building exterior wall is not less than 1-hour fire-resistance rated for a distance on each side of the fire wall equal to the depth of the projecting element. Openings within such exterior walls shall be protected by opening protectives having a fire protection rating of not less than [3] / 4 hour.
• CBC § 2.1 High relevance — show source text

  agency	BSC	BSC- CG	SFM	HCD	Col6	Col7	DSA	Col9	Col10	OSHPD	Col12	Col13	Col14	Col15	Col16	Col17	BSCC	DPH	AGR	DWR	CEC	CA	SL	SLC
  Adopting agency	BSC	BSC- CG	SFM	1	2	1/AC	AC	SS	SS/CC	1	1R	2	3	4	5	6	6	6	6	6	6	6	6	6
  Adopt entire chapter	X			X	X								X			X
  Adopt entire chapter as amended (amended sections listed below)								X	X	X	X	X		X	X
  Adopt only those sections that are listed below		X	X																		X
  Chapter / Section
  1401			X
  1402			X
  1402.2.1		X
  1403			X
  1404			X
  1404.1.2								X	X	X	X	X		X	X
  1404.3.3																					X
  1405			X
  1406			X
  1407			X
  1408			X
  1411			X
  1412			X
  1413								X	X	X	X	X		X	X

  The state agency does not adopt sections identified with the following symbol: The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.

  2025 CALIFORNIA BUILDING CODE 14-1

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

  14-2 2025 CALIFORNIA BUILDING CODE

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

  14 EXTERIOR WALLS

  User notes:

  About this chapter: Chapter 14 addresses requirements for exterior walls of buildings. Minimum standards for wall covering materials, such as material performance and fire resistance, installation of wall coverings and the ability of the wall to provide weather protection are provided. This chapter also contains limitations on the areas and heights of combustible wall coverings based on fire separation distances, radiant heat exposure and surface burning characteristics.

• CBC § 706.4 High relevance — show source text

  TABLE 706.4—FIRE WALL FIRE-RESISTANCE RATINGS	Col2
  GROUP	FIRE-RESISTANCE RATING (hours)
  A, B, E, H-4, I, R-1, R-2,_R-2.1, R-2.2,_U,L	3 a
  F-1, H-3b, H-5, M, S-1	3
  H-1, H-2	4 b
  F-2, S-2, R-3, R-4	2
  a. In Type II or V construction, walls shall be permitted to have a 2-hour fire-resistance rating. b. For Group H-1, H-2 or H-3 buildings, also see Sections 415.7 and 415.8.	a. In Type II or V construction, walls shall be permitted to have a 2-hour fire-resistance rating. b. For Group H-1, H-2 or H-3 buildings, also see Sections 415.7 and 415.8.

  706.5 Horizontal continuity. Fire walls shall be continuous from exterior wall to exterior wall and shall extend not less than 18 inches (457 mm) beyond the exterior surface of exterior walls.

  Exceptions:

  1. Fire walls shall be permitted to terminate at the interior surface of combustible exterior sheathing or siding provided that the exterior wall has a fire-resistance rating of not less than 1 hour for a horizontal distance of not less than 4 feet (1220 mm) on both sides of the fire wall. Openings within such exterior walls shall be protected by opening protectives having a fire protection rating of not less than [3] / 4 hour.
  2. Fire walls shall be permitted to terminate at the interior surface of noncombustible exterior sheathing, exterior siding or other noncombustible exterior finishes provided that the sheathing, siding or other exterior noncombustible finish extends a horizontal distance of not less than 4 feet (1220 mm) on both sides of the fire wall.
  3. Fire walls shall be permitted to terminate at the interior surface of noncombustible exterior sheathing where the building on each side of the fire wall is protected by an automatic sprinkler system installed in accordance with Section 903.3.1.1 or 903.3.1.2.

  7-12 2025 CALIFORNIA BUILDING CODE

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

  FIRE AND SMOKE PROTECTION FEATURES

  706.5.1 Exterior walls. Where the fire wall intersects exterior walls, the fire-resistance rating and opening protection of the exterior walls shall comply with one of the following:

  1. The exterior walls on both sides of the fire wall shall have a 1-hour fire-resistance rating with [3] / 4 -hour protection where opening protection is required by Section 705.9. The fire-resistance rating of the exterior wall shall extend not less than 4 feet (1220 mm) on each side of the intersection of the fire wall to exterior wall. Exterior wall intersections at fire walls that form an angle equal to or greater than 180 degrees (3.14 rad) do not need exterior wall protection.
  2. Buildings or spaces on both sides of the intersecting fire wall shall assume to have an imaginary lot line at the fire wall and extending beyond the exterior of the fire wall.
• CBC § 1.2 Medium relevance — show source text

  1_||X||||||||||||||||||||||| |1403|||X|||||||||||||||||||||| |1404|||X|||||||||||||||||||||| |1404.1.2||||||||X|X|X|X|X||X|X|||||||||| |1404.3.3|||||||||||||||||||||X|||| |1405|||X|||||||||||||||||||||| |1406|||X|||||||||||||||||||||| |1407|||X|||||||||||||||||||||| |1408|||X|||||||||||||||||||||| |1411|||X|||||||||||||||||||||| |1412|||X|||||||||||||||||||||| |1413||||||||X|X|X|X|X||X|X||||||||||

  The state agency does not adopt sections identified with the following symbol: The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.

  2025 CALIFORNIA BUILDING CODE 14-1

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

  14-2 2025 CALIFORNIA BUILDING CODE

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

  14 EXTERIOR WALLS

  User notes:

  About this chapter: Chapter 14 addresses requirements for exterior walls of buildings. Minimum standards for wall covering materials, such as material performance and fire resistance, installation of wall coverings and the ability of the wall to provide weather protection are provided. This chapter also contains limitations on the areas and heights of combustible wall coverings based on fire separation distances, radiant heat exposure and surface burning characteristics.

  ICC code development note: Code change proposals to sections preceded by the designation [BS] will be considered by the IBC—Structural Code Development

  Committee during the 2025 (Group B) Code Development Cycle.

  SECTION 1401—GENERAL

  1401.1 Scope. The provisions of this chapter shall establish the minimum requirements for exterior walls, exterior wall assemblies, exterior wall coverings, exterior wall openings, exterior windows and doors, exterior soffits and fascias, and architectural trim.

  SECTION 1402—PERFORMANCE REQUIREMENTS

  1402.1 General. The provisions of this section shall apply to exterior walls, exterior wall coverings and components thereof.

  1402.2 Weather protection. Buildings shall be provided with a weather-resistant exterior wall assembly. The exterior wall assembly shall include flashing, as described in Section 1404.4. The exterior wall assembly shall be designed and constructed in such a manner as to prevent the accumulation of water within the exterior wall assembly by providing a water-resistive barrier behind the exterior veneer, as described in Section 1403.2, and a means for draining water that enters the assembly to the exterior. Protection against condensation in the exterior wall assembly shall be provided in accordance with Section 1404.3.

  Exceptions:

  1. A weather-resistant exterior wall assembly shall not be required over concrete or masonry walls designed in accordance with Chapters 19 and 21, respectively.
  2. Compliance with the requirements for a means of drainage, and the requirements of Sections 1403.2 and 1404.4, shall not be required for an exterior wall assembly that has been demonstrated through testing to resist wind-driven rain, including joints, penetrations and intersections with dissimilar materials, in accordance with ASTM E331 under the following conditions:
• CBC § 903.3.1.1 Medium relevance — show source text

  Such openings shall be separated vertically not less than 3 feet (914 mm) by spandrel girders, exterior walls or other similar assemblies that have a fireresistance rating of not less than 1 hour, rated for exposure to fire from both sides, or by flame barriers that extend horizontally not less than 30 inches (762 mm) beyond the exterior wall. Flame barriers shall have a fire-resistance rating of not less than 1 hour. The unexposed surface temperature limitations specified in ASTM E119 or UL 263 shall not apply to the flame barriers unless otherwise required by the provisions of this code.

  Exceptions:

  1. This section shall not apply to buildings that are three stories or less above grade plane.
  2. This section shall not apply to buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1 or 903.3.1.2.

  7-10 2025 CALIFORNIA BUILDING CODE

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

  FIRE AND SMOKE PROTECTION FEATURES

  3. Open parking garages. 705.9.6 Vertical exposure. For buildings on the same lot, opening protectives having a fire protection rating of not less than [3] / 4 hour shall be provided in every opening that is less than 15 feet (4572 mm) vertically above the roof of an adjacent building or structure based on assuming an imaginary line between them. The opening protectives are required where the fire separation distances from the imaginary line to each building or structure are less than 15 feet (4572 mm).

  Exceptions:

  1. Opening protectives are not required where the roof assembly of the adjacent building or structure has a fire-resistance rating of not less than 1 hour for a minimum distance of 10 feet (3048 mm) from the exterior wall facing the imaginary line and the entire length and span of the supporting elements for the fire-resistance-rated roof assembly has a fire-resistance rating of not less than 1 hour.
  2. Buildings on the same lot and considered as portions of one building in accordance with Section 705.3 are not required to comply with Section 705.9.6.

  705.10 Joints. Joints made in or between exterior walls required by this section to have a fire-resistance rating shall comply with Section 715.

  Exception: Joints in exterior walls that are permitted to have unprotected openings.

  705.10.1 Voids. The void created at the intersection of a floor/ceiling assembly and an exterior curtain wall assembly shall be protected in accordance with Section 715.4.

  705.11 Ducts and air transfer openings. Penetrations by air ducts and air transfer openings in fire-resistance-rated exterior walls required to have protected openings shall comply with Section 717.

  Exception: Foundation vents installed in accordance with this code are permitted.

  705.12 Parapets. Parapets shall be provided on exterior walls of buildings.

  Exceptions: A parapet need not be provided on an exterior wall where any of the following conditions exist:

  1. The wall is not required to be fire-resistance rated in accordance with Table 705.5 because of fire separation distance.
  2. The building has an area of not more than 1,000 square feet (93 m [2] ) on any floor.
  3. Walls that terminate at roofs of not less than 2-hour fire-resistance-rated construction or where the roof, including the deck or slab and supporting construction, is constructed entirely of noncombustible materials.
• CBC § 705.5 Medium relevance — show source text

  The location of the assumed line in relation to the exterior walls and the fire wall shall be such that the exterior wall and opening protection meet the requirements set forth in Sections 705.5 and 705.9. Such protection is not required for exterior walls terminating at fire walls that form an angle equal to or greater than 180 degrees (3.14 rad).

  706.5.2 Horizontal projecting elements. Fire walls shall extend to the outer edge of horizontal projecting elements such as balconies, roof overhangs, canopies, marquees and similar projections that are within 4 feet (1220 mm) of the fire wall.

  Exceptions:

  1. Horizontal projecting elements without concealed spaces, provided that the exterior wall behind and below the projecting element has not less than 1-hour fire-resistance-rated construction for a distance not less than the depth of the projecting element on both sides of the fire wall. Openings within such exterior walls shall be protected by opening protectives having a fire protection rating of not less than [3] / 4 hour.
  2. Noncombustible horizontal projecting elements with concealed spaces, provided that a minimum 1-hour fire-resistance-rated wall extends through the concealed space. The projecting element shall be separated from the building by not less than 1-hour fire-resistance-rated construction for a distance on each side of the fire wall equal to the depth of the projecting element. The wall is not required to extend under the projecting element where the building exterior wall is not less than 1-hour fire-resistance rated for a distance on each side of the fire wall equal to the depth of the projecting element. Openings within such exterior walls shall be protected by opening protectives having a fire protection rating of not less than [3] / 4 hour.
  3. For combustible horizontal projecting elements with concealed spaces, the fire wall need only extend through the concealed space to the outer edges of the projecting elements. The exterior wall behind and below the projecting element shall be of not less than 1-hour fire-resistance-rated construction for a distance not less than the depth of the projecting elements on both sides of the fire wall. Openings within such exterior walls shall be protected by opening protectives having a fire protection rating of not less than [3] / 4 hour.

  706.6 Vertical continuity. Fire walls shall extend from the foundation to a termination point not less than 30 inches (762 mm) above both adjacent roofs.

  Exceptions:

  1. Stepped buildings in accordance with Section 706.6.1.
  2. Two-hour fire-resistance-rated walls shall be permitted to terminate at the underside of the roof sheathing, deck or slab, provided that all of the following requirements are met: 2.1. The lower roof assembly within 4 feet (1220 mm) of the wall has not less than a 1-hour fire-resistance rating and the entire length and span of supporting elements for the rated roof assembly has a fire-resistance rating of not less than 1 hour.

  2.2. Openings in the roof shall not be located within 4 feet (1220 mm) of the fire wall. 2.3. Each building shall be provided with not less than a Class B roof covering. 3. Walls shall be permitted to terminate at the underside of noncombustible roof sheathing, deck or slabs where both buildings are provided with not less than a Class B roof covering. Openings in the roof shall not be located within 4 feet (1220 mm) of the fire wall. 4.

• CBC § 705.9.1 Medium relevance — show source text

  Where Section 705.9.1 permits nonbearing exterior walls with unlimited area of unprotected openings, the required fire-resistance rating for the exterior walls is 0 hours.
  h. For a building containing only a Group U occupancy private garage or carport, the exterior wall shall not be required to have a fire-resistance rating where the fire separation
  distance is 5 feet (1523 mm) or greater_or where equipped throughout with an automatic sprinkler system in accordance with Section 903.3 the fire-resistance rating shall not be_
  required where the fire separation distance is 3 feet or greater.
  i. For a Group R-3 building of Type II-B or Type V-B construction, the exterior wall shall not be required to have a fire-resistance rating where the fire separation distance is 5 feet
  (1523 mm) or greater_ or where equipped throughout with an automatic sprinkler system in accordance with Section 903.3 the fire-resistance rating shall not be required where_
  the fire separation distance is 3 feet or greater.|For SI: 1 foot = 304.8 mm.
  a. Load-bearing exterior walls shall also comply with the fire-resistance rating requirements of Table 601.
  b. See Section 706.1.1 for party walls.
  c. Open parking garages complying with Section 406 shall not be required to have a fire-resistance rating.
  d. The fire-resistance rating of an exterior wall is determined based upon the fire separation distance of the exterior wall and the story in which the wall is located.
  e. For special requirements for Group H occupancies, see Section 415.6.
  f. For special requirements for Group S aircraft hangars, see Section 412.3.1.
  g. Where Section 705.9.1 permits nonbearing exterior walls with unlimited area of unprotected openings, the required fire-resistance rating for the exterior walls is 0 hours.
  h. For a building containing only a Group U occupancy private garage or carport, the exterior wall shall not be required to have a fire-resistance rating where the fire separation
  distance is 5 feet (1523 mm) or greater_or where equipped throughout with an automatic sprinkler system in accordance with Section 903.3 the fire-resistance rating shall not be_
  required where the fire separation distance is 3 feet or greater.
  i. For a Group R-3 building of Type II-B or Type V-B construction, the exterior wall shall not be required to have a fire-resistance rating where the fire separation distance is 5 feet
  (1523 mm) or greater_ or where equipped throughout with an automatic sprinkler system in accordance with Section 903.3 the fire-resistance rating shall not be required where_
  the fire separation distance is 3 feet or greater.|

  705.6 Continuity. The fire-resistance rating of exterior walls shall extend from the top of the foundation or floor/ceiling assembly below to one of the following:

  1. The underside of the floor sheathing, roof sheathing, deck or slab above.
  2. The underside of a floor/ceiling or roof/ceiling assembly having a fire-resistance rating equal to or greater than the exterior wall and the fire separation distance is greater than 10 feet.

  Parapets shall be provided as required by Section 705.12.

• CBC § 705.10 Medium relevance — show source text

  705.10 Joints. Joints made in or between exterior walls required by this section to have a fire-resistance rating shall comply with Section 715.

  Exception: Joints in exterior walls that are permitted to have unprotected openings.

  705.10.1 Voids. The void created at the intersection of a floor/ceiling assembly and an exterior curtain wall assembly shall be protected in accordance with Section 715.4.

  705.11 Ducts and air transfer openings. Penetrations by air ducts and air transfer openings in fire-resistance-rated exterior walls required to have protected openings shall comply with Section 717.

  Exception: Foundation vents installed in accordance with this code are permitted.

  705.12 Parapets. Parapets shall be provided on exterior walls of buildings.

  Exceptions: A parapet need not be provided on an exterior wall where any of the following conditions exist:

  1. The wall is not required to be fire-resistance rated in accordance with Table 705.5 because of fire separation distance.
  2. The building has an area of not more than 1,000 square feet (93 m [2] ) on any floor.
  3. Walls that terminate at roofs of not less than 2-hour fire-resistance-rated construction or where the roof, including the deck or slab and supporting construction, is constructed entirely of noncombustible materials.
  4. One-hour fire-resistance-rated exterior walls that terminate at the underside of the roof sheathing, deck or slab, provided that: 4.1. Where the roof/ceiling framing elements are parallel to the walls, such framing and elements supporting such framing shall not be of less than 1-hour fire-resistance-rated construction for a width of 4 feet (1220 mm) for Groups R and U and 10 feet (3048 mm) for other occupancies, measured from the interior side of the wall. 4.2. Where roof/ceiling framing elements are not parallel to the wall, the entire span of such framing and elements supporting such framing shall not be of less than 1-hour fire-resistance-rated construction. 4.3. Openings in the roof shall not be located within 5 feet (1524 mm) of the 1-hour fire-resistance-rated exterior wall for Groups R and U and 10 feet (3048 mm) for other occupancies, measured from the interior side of the wall. 4.4. The entire building shall be provided with not less than a Class B roof covering.
  5. In Groups R-2 and R-3 where the entire building is provided with a Class C roof covering, the exterior wall shall be permitted to terminate at the underside of the roof sheathing or deck in Types III, IV and V construction, provided that one or both of the following criteria is met: 5.1. The roof sheathing or deck is constructed of approved noncombustible materials or of fire-retardant-treated wood for a distance of 4 feet (1220 mm). 5.2. The roof is protected with 0.625-inch (16 mm) Type X gypsum board directly beneath the underside of the roof sheathing or deck, supported by not less than nominal 2-inch (51 mm) ledgers attached to the sides of the roof framing members for a minimum distance of 4 feet (1220 mm).
  6. Where the wall is permitted to have not less than 25 percent of the exterior wall areas containing unprotected openings based on fire separation distance as determined in accordance with Section 705.9.
• CBC § 1404.6. Medium relevance — show source text

  4. Wood veneers shall comply with Section 1404.6.

  1405.1.1.1 Ignition resistance. Where permitted by Section 1405.1.1, combustible exterior wall coverings shall be tested in accordance with NFPA 268.

  Exceptions:

  1. Wood or wood-based products.
  2. Other combustible materials covered with an exterior weather covering, other than vinyl sidings, included in and complying with the thickness requirements of Table 1404.2.
  3. Aluminum having a minimum thickness of 0.019 inch (0.48 mm).

  1405.1.1.1.1 Fire separation 5 feet or less. Where installed on exterior walls having a fire separation distance of 5 feet (1524 mm) or less, combustible exterior wall coverings shall not exhibit sustained flaming as defined in NFPA 268.

  1405.1.1.1.2 Fire separation greater than 5 feet. For fire separation distances greater than 5 feet (1524 mm), any exterior wall covering shall be permitted that has been exposed to a reduced level of incident radiant heat flux in accordance with the NFPA 268 test method without exhibiting sustained flaming. The minimum fire separation distance required for the exterior wall covering shall be determined from Table 1405.1.1.1.2 based on the maximum tolerable level of incident radiant heat flux that does not cause sustained flaming of the exterior wall covering.

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  EXTERIOR WALLS

  TABLE 1405.1.1.1.2—MINIMUM FIRE SEPARATION FOR COMBUSTIBLE EXTERIOR WALL COVERINGS	Col2
  FIRE SEPARATION DISTANCE (feet)	TOLERABLE LEVEL INCIDENT RADIANT HEAT ENERGY (kW/m2)
  5	12.5
  6	11.8
  7	11.0
  8	10.3
  9	9.6
  10	8.9
  11	8.3
  12	7.7
  13	7.2
  14	6.7
  15	6.3
  16	5.9
  17	5.5
  18	5.2
  19	4.9
  20	4.6
  21	4.4
  22	4.1
  23	3.9
  24	3.7
  25	3.5
  For SI: 1 foot = 304.8 mm, 1 Btu/H2 × °F = 0.0057 kW/m2 × K.	For SI: 1 foot = 304.8 mm, 1 Btu/H2 × °F = 0.0057 kW/m2 × K.

  1405.1.2 Location. Combustible exterior wall coverings located along the top of exterior walls shall be completely backed up by the exterior wall and shall not extend over or above the top of the exterior wall.

• CBC § 3-23 Medium relevance — show source text

  The dead load of supported materials shall be included when calculating the deflection of these members.|

  R301.8 Nominal sizes. For the purposes of this code, dimensions of lumber specified shall be deemed to be nominal dimensions unless specifically designated as actual dimensions.

  SECTION R302 —FIRE-RESISTANT CONSTRUCTION

  R302.1 Exterior walls. Construction, projections, openings and penetrations of exterior walls of dwellings , townhouses and accessory buildings shall comply with Table R302.1(1) based on fire separation distance; or dwellings and accessory buildings equipped throughout with an automatic sprinkler system installed in accordance with Section R309 shall comply with Table R302.1(2) based on fire separation distance.

  For the purposes of determining fire separation distance, dwellings and townhouses on the same lot shall be assumed to have an imaginary line between them. Where a new dwelling or townhouse is to be erected on the same lot as an existing dwelling or townhouse, the location of the assumed imaginary line with relation to the existing dwelling or townhouse shall be such that the existing dwelling or townhouse meets requirements of this section.

  Where a lot line exists between adjacent townhouse units, fire separation distance of exterior walls shall be measured to the lot line. Where a lot line does not exist between adjacent townhouse units, an imaginary line shall be assumed between the adjacent townhouse units and fire separation distance of exterior walls shall be measured to the imaginary line. Fire separation distance and requirements of Section R302.1 shall not apply to walls separating townhouse units that are required by Section R302.2.

  Exceptions:

  1. Walls, projections, openings or penetrations in walls perpendicular to the line used to determine the fire separation distance.

  2025 CALIFORNIA RESIDENTIAL CODE 3-23

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  BUILDING PLANNING

  2. Walls of individual dwelling units and their accessory buildings located on the same lot.

  3. Detached tool sheds and storage sheds, playhouses and similar structures exempted from permits are not required to provide wall protection based on location on the lot. Projections beyond the exterior wall shall not extend over the lot line.

  4. Detached garages accessory to a dwelling unit located within 2 feet (610 mm) of a lot line are permitted to have roof eave projections not exceeding 4 inches (102 mm).

  5. Foundation vents installed in compliance with this code are permitted.

  TABLE R302.1(1)—EXTERIOR WALLS	Col2	Col3	Col4
  ** EXTERIOR WALL ELEMENT**	** EXTERIOR WALL ELEMENT**	** MINIMUM FIRE-RESISTANCE RATING**	** MINIMUM FIRE** SEPARATION DISTANCE
  Walls	Fire-resistance rated	1 hour—tested in accordance with ASTM E119, UL 263 or Section 703.2.2 of the_California Building Code_ with exposure from both sides	0 feet
  Walls	Not fire-resistance rated	0 hours	≥ 5 feet
  Projections	Not allowed	NA	< 2 feet
  Projections	Fire-resistance rated	1 hour on the underside, or heavy timber, or fire-retardant-treated wooda,

• CBC § 2303.2 Medium relevance — show source text

  2. Combustible exterior wall coverings shall be limited to 40 feet (12 192 mm) in height above grade plane. Exceptions:
  3. Metal composite material (MCM) systems complying with Section 1406.
  4. Exterior insulation and finish systems (EIFS) complying with Section 1407.
  5. High-pressure decorative exterior-grade compact laminate (HPL) systems complying with Section 1408.
  6. Exterior wall coverings containing foam plastic insulation complying with Section 2603.
  7. Combustible exterior wall coverings constructed of fire-retardant-treated wood complying with Section 2303.2 for exterior installation shall not be limited in wall surface area where the fire separation distance is 5 feet (1524 mm) or less and shall be permitted up to 60 feet (18 288 mm) in height above grade plane regardless of the fire separation distance.
  8. Wood veneers shall comply with Section 1404.6.

  1405.1.1.1 Ignition resistance. Where permitted by Section 1405.1.1, combustible exterior wall coverings shall be tested in accordance with NFPA 268.

  Exceptions:

  1. Wood or wood-based products.
  2. Other combustible materials covered with an exterior weather covering, other than vinyl sidings, included in and complying with the thickness requirements of Table 1404.2.
  3. Aluminum having a minimum thickness of 0.019 inch (0.48 mm).

  1405.1.1.1.1 Fire separation 5 feet or less. Where installed on exterior walls having a fire separation distance of 5 feet (1524 mm) or less, combustible exterior wall coverings shall not exhibit sustained flaming as defined in NFPA 268.

  1405.1.1.1.2 Fire separation greater than 5 feet. For fire separation distances greater than 5 feet (1524 mm), any exterior wall covering shall be permitted that has been exposed to a reduced level of incident radiant heat flux in accordance with the NFPA 268 test method without exhibiting sustained flaming. The minimum fire separation distance required for the exterior wall covering shall be determined from Table 1405.1.1.1.2 based on the maximum tolerable level of incident radiant heat flux that does not cause sustained flaming of the exterior wall covering.

  14-16 2025 CALIFORNIA BUILDING CODE

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

  EXTERIOR WALLS