ADOPTS WITH AMENDMENTS:

International Building Code 2021 (IBC 2021)

Heads up: There are no amended sections in this chapter.
CALIFORNIA BUILDING CODE — MATRIX ADOPTION TABLE
CHAPTER 12 — INTERIOR ENVIRONMENT
(Matrix Adoption Tables are nonregulatory, intended only as an aid to the code user.
See Chapter 1 for state agency authority and building applications.)
Adopting agency BSC BSC-
CG
SFM HCD DSA OSHPD BSCC DPH AGR DWR CEC CA SL SLC
1 2 1/AC AC SS SS/CC 1 1R 2 3 4 5
Adopt entire chapter               X X                            
Adopt entire chapter as amended (amended sections listed below) X     X X         X X X X X X                
Adopt only those sections that are listed below   X X                         X X X     X    
Chapter / Section                                              
1202.1       X X                                    
1202.2.1       X X                                    
1202.3       X X                                    
1202.4.1.3                                         X    
1202.5       X X                                    
1202.5.2.1       X X                                    
1202.6     X                                        
1203.1, Exceptions 2 & 4       X X                                    
1203.1, Exception 3                   X X X X X X                
Table 1203.3.1                                       X      
1203.4.1.1                                         X    
1203.4.2                                         X    
1204.1       X X                                    
1204.4.1       X X                                    
1204.6   X                                          
1204.7 X                                            
1204.7.1 X                                            
1205     X                                        
1206.3, Exception       X X                                    
1206.4       X X                                    
1206.5   X                                          
1208.1       X                                      
1208.2                   X X X X X X                
1208.2, Exception 5                   X   X X   X                
1208.2, Exception 6                           X                  
1208.4       X                                      
1209     X                                        
1209.1.1                                         X    
1210.2                   X   X X X X                
1211 — 1211.6       X X                                    
1212       X                                      
Table 1224.4.6.5                   X X X X X X                
1224                   X                          
1225                       X                      
1226                         X                    
1227                           X                  
1228                             X                
1230                               X              
1231                               X              
1235                                 X            
1236                                 X            
1237                                 X            
1240                                   X          
1241                                   X          
1242                                   X          
1243                                   X          
1250                                       X      
1251                                       X      
1252                                       X      
1253                                       X      
1254                                       X      
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.
User note:
About this chapter: Chapter 12 provides minimum provisions for the interior of buildings—the occupied environment. Ventilation, lighting, and space heating are directly regulated in this chapter and in conjunction with the California Mechanical Code and the California Energy Code. Minimum room size, maximum room-to-room sound transmission and classroom acoustics are set for educational occupancies.
The provisions of this chapter shall govern ventilation, temperature control, lighting, yards and courts, sound transmission, room dimensions, surrounding materials and rodentproofing associated with the interior spaces of buildings.
Buildings shall be provided with natural ventilation in accordance with Section 1202.5, or mechanical ventilation in accordance with the California Mechanical Code.
Roof assemblies shall be ventilated in accordance with this section or shall comply with Section 1202.3.
Enclosed attics and enclosed rafter spaces formed where ceilings are applied directly to the underside of roof framing members shall have cross ventilation for each separate space by ventilation openings protected against the entrance of rain and snow. Blocking and bridging shall be arranged so as not to interfere with the movement of air. An airspace of not less than 1 inch (25 mm) shall be provided between the insulation and the roof sheathing. The net free ventilating area shall be not less than 1/150 of the area of the space ventilated. Ventilators shall be installed in accordance with manufacturer's installation instructions.
Exception: The net free cross-ventilation area shall be permitted to be reduced to 1/300 provided both of the following conditions are met:
  1. In Climate Zones 6, 7 and 8, a Class I or II vapor retarder is installed on the warm-in-winter side of the ceiling.
  2. At least 40 percent and not more than 50 percent of the required venting area is provided by ventilators located in the upper portion of the attic or rafter space. Upper ventilators shall be located not more than 3 feet (914 mm) below the ridge or highest point of the space, measured vertically, with the balance of the ventilation provided by eave or cornice vents. Where the location of wall or roof framing members conflicts with the installation of upper ventilators, installation more than 3 feet (914 mm) below the ridge or highest point of the space shall be permitted.
Exterior openings into the attic space of any building intended for human occupancy shall be protected to prevent the entry of birds, squirrels, rodents, snakes and other similar creatures. Openings for ventilation having a least dimension of not less than 1/16 inch (1.6 mm) and not more than 1/4 inch (6.4 mm) shall be permitted. Openings for ventilation having a least dimension larger than 1/4 inch (6.4 mm) shall be provided with corrosion-resistant wire cloth screening, hardware cloth, perforated vinyl or similar material with openings having a least dimension of not less than 1/16 inch (1.6 mm) and not more than 1/4 inch (6.4 mm). Where combustion air is obtained from an attic area, it shall be in accordance with Chapter 7 of the California Mechanical Code.
Unvented attics and unvented enclosed roof framing assemblies created by ceilings applied directly to the underside of the roof framing members/rafters and the structural roof sheathing at the top of the roof framing members shall be permitted where all of the following conditions are met:
  1. The unvented attic space is completely within the building thermal envelope.
  2. No interior Class I vapor retarders are installed on the ceiling side (attic floor) of the unvented attic assembly or on the ceiling side of the unvented enclosed roof framing assembly.
  3. Where wood shingles or shakes are used, not less than a 1/4-inch (6.4 mm) vented airspace separates the shingles or shakes and the roofing underlayment above the structural sheathing.
  4. In Climate Zones 5, 6, 7 and 8, any air-impermeable insulation shall be a Class II vapor retarder or shall have a Class II vapor retarder coating or covering in direct contact with the underside of the insulation.
    1. [HCD 1 & HCD 2] In California Climate Zones 14 and 16, a Class I or Class II vapor retarder shall be installed on the indirectly conditioned space side of all insulation in an unvented attic with air-permeable insulation, for condensation control.
  5. Insulation shall comply with either Item 5.1 or 5.2, and additionally Item 5.3.
    1. Item 5.1.1, 5.1.2, 5.1.3 or 5.1.4 shall be met, depending on the air permeability of the insulation directly under the structural roof sheathing. [HCD 1 & HCD 2] No insulation shall be required when roof tiles, wood shingles or wood shakes, or any other roofing system using battens and no continuous underlayment is installed. A continuous underlayment shall be considered to exist if sheathing, roofing paper or any continuous layer having a perm rate of no more than one perm under the dry cup method is present.
      1.  Where only air-impermeable insulation is provided, it shall be applied in direct contact with the underside of the structural roof sheathing.
      2. Where air-permeable insulation is provided inside the building thermal envelope, it shall be installed in accordance with Item 5.1.1. In addition to the air-permeable insulation installed directly below the structural sheathing, rigid board or sheet insulation shall be installed directly above the structural roof sheathing in accordance with the R-values in Table 1202.3 for condensation control.
      3. Where both air-impermeable and air-permeable insulation are provided, the air-impermeable insulation shall be applied in direct contact with the underside of the structural roof sheathing and shall be in accordance with the R-values in Table 1202.3 for condensation control. The air-permeable insulation shall be installed directly under the air-impermeable insulation.
      4. Alternatively, sufficient rigid board or sheet insulation shall be installed directly above the structural roof sheathing to maintain the monthly average temperature of the underside of the structural roof sheathing above 45°F (7°C). For calculation purposes, an interior air temperature of 68°F (20°C) is assumed and the exterior air temperature is assumed to be the monthly average outside air temperature of the three coldest months.
    2. In Climate Zones 1, 2 and 3, air-permeable insulation installed in unvented attics shall meet the following requirements:
      1. A vapor diffusion port shall be installed not more than 12 inches (305 mm) from the highest point of the roof, measured vertically from the highest point of the roof to the lower edge of the port.
      2. The port area shall be greater than or equal to 1/600 of the ceiling area. Where there are multiple ports in the attic, the sum of the port areas shall be greater than or equal to the area requirement.
      3. The vapor permeable membrane in the vapor diffusion port shall have a vapor permeance rating of greater than or equal to 20 perms when tested in accordance with Procedure A of ASTM E96.
      4. The vapor diffusion port shall serve as an air barrier between the attic and the exterior of the building.
      5. The vapor diffusion port shall protect the attic against the entrance of rain and snow.
      6. Framing members and blocking shall not block the free flow of water vapor to the port. Not less than a 2-inch (50 mm) space shall be provided between any blocking and the roof sheathing. Air-permeable insulation shall be permitted within that space.
      7. The roof slope shall be greater than or equal to 3 units vertical in 12 units horizontal (3:12).
      8. Where only air-permeable insulation is used, it shall be installed directly below the structural roof sheathing, on top the attic floor, or on top of the ceiling.
      9. Where only air-permeable insulation is used and is installed directly below the structural roof sheathing, air shall be supplied at a flow rate greater than or equal to 50 cubic feet per minute (23.6 L/s) per 1,000 square feet (93 m2) of ceiling.
    3. The air shall be supplied from ductwork providing supply air to the occupiable space when the conditioning system is operating. Alternatively, the air shall be supplied by a supply fan when the conditioning system is operating. Where preformed insulation board is used as the airimpermeable insulation layer, it shall be sealed at the perimeter of each individual sheet interior surface to form a continuous layer.
Exceptions:
  1. Section 1202.3 does not apply to special use structures or enclosures such as swimming pool enclosures, data processing centers, hospitals or art galleries.
  2. Section 1202.3 does not apply to enclosures in Climate Zones 5 through 8 that are humidified beyond 35 percent during the three coldest months.
TABLE 1202.3
INSULATION FOR CONDENSATION CONTROL
CLIMATE ZONE MINIMUM R-VALUE OF AIR-
IMPERMEABLE INSULATIONa
2B and 3B tile roof only 0 (none required)
1, 2A, 2B, 3A, 3B, 3C R-5
4C R-10
4A, 4B R-15
5 R-20
6 R-25
7 R-30
8 R-35
  1. Contributes to, but does not supersede, thermal resistance requirements for attic and roof assemblies in the California Energy Code.
The IECC climate zones used by this section differ from those used by the California Energy Code to determine applicability of energy efficiency measures. Comparison of IECC and California Energy Code climate zones is shown in Table 1202.3.1.
TABLE 1202.3.1
IECC VERSUS CALIFORNIA ENERGY CODE CLIMATE ZONE COMPARISON
IECCa CALIFORNIA
ENERGY
CODE
DESCRIPTIONb
6 16 Includes Alpine, Mono Counties
5 11, 12, 16 Includes Siskiyou, Modoc, Lassen,
Plumas, Sierra, Nevada Counties
4 (marine) 1, 2, 16 Includes Del Norte and Humboldt
Counties
4 2, 12, 13, 16 Includes Inyo, Trinity, Lake, El Dorado,
Amador, Calaveras, Tuolumne, Mariposa
Counties
3 8, 9, 10, 11,
12, 13, 14
, 15, 16
Includes Shasta, Tehama, Butte, Glenn,
Colusa, Yuba, Contra Costa, Sutter, Yolo
, Sacramento, Placer, San Joaquin,
Solano, Stanislaus, Merced, Madera
, Fresno, Kings, Tulare, Kern, Ventura,
Los Angeles, Orange, San Bernardino
, Riverside Counties
3 (marine) 1, 2, 3, 4, 5,
6, 9, 12, 16
Includes Mendocino, Sonoma, Marin,
San Francisco, San Mateo, Alameda
, Santa Cruz, Monterey, San Benito,
San Luis Obispo, Santa Barbara
, Ventura, San Diego Counties
2 14, 16 Includes Imperial County
  1. IECC Climate Zones 1, 7 and 8 do not occur in California, nor do any IECC moist climate zones.
  2. IECC boundaries are defined by county political boundary lines. California Energy Code boundaries are based on a metes and bounds specifications aligned with climate-affecting geographic features, which often do not coincide with county lines.
The space between the bottom of the floor joists and the earth under any building except spaces occupied by basements or cellars shall be provided with ventilation in accordance with Section 1202.4.1, 1202.4.2 or 1202.4.3.
Ventilation openings through foundation walls shall be provided. The openings shall be placed so as to provide cross ventilation of the under-floor space. The net area of ventilation openings shall be in accordance with Section 1202.4.1.1 or 1202.4.1.2. Ventilation openings shall be covered for their height and width with any of the following materials, provided that the least dimension of the covering shall be not greater than 1/4 inch (6.4 mm):
  1. Perforated sheet metal plates not less than 0.070 inch (1.8 mm) thick.
  2. Expanded sheet metal plates not less than 0.047 inch (1.2 mm) thick.
  3. Cast-iron grilles or gratings.
  4. Extruded load-bearing vents.
  5. Hardware cloth of 0.035-inch (0.89 mm) wire or heavier.
  6. Corrosion-resistant wire mesh, with the least dimension not greater than 1/8 inch (3.2 mm).
  7. Operable louvres, where ventilation is provided in accordance with Section 1202.4.1.2.
The net area of ventilation openings for crawl spaces with uncovered earth floors shall be not less than 1 square foot for each 150 square feet (0.67 m2 for each 100 m2) of crawl space area.
The net area of ventilation openings for crawl spaces with the ground surface covered with a Class I vapor retarder shall be not less than 1 square foot for each 1,500 square feet (0.67 m2 for each 1000 m2) of crawl space area.
[SPCB] Openings for under-floor ventilation shall be not less than 1 1/2 square feet (0.135 m2) for each 25 linear feet (7620 linear mm) of exterior wall. They shall be covered with corrosion-resistant wire mesh with mesh openings not less than 1/4 inch (6.4 mm) nor more than 1/2 inch (13 mm) in any dimension.
In extremely cold climates, where a ventilation opening will cause a detrimental loss of energy, ventilation openings to the interior of the structure shall be provided.
Mechanical ventilation shall be provided to crawl spaces where the ground surface is covered with a Class I vapor retarder. Ventilation shall be in accordance with Section 1202.4.3.1 or 1202.4.3.2.
Continuously operated mechanical ventilation shall be provided at a rate of 1.0 cubic foot per minute (cfm) for each 50 square feet (1.02 L/s for each 10 m2) of crawl space ground surface area and the ground surface shall be covered with a Class I vapor retarder.
The crawl space shall be conditioned in accordance with the California Mechanical Code and the walls of the crawl space shall be insulated in accordance with the California Energy Code.
For buildings in flood hazard areas as established in Section 1612.3, the openings for under-floor ventilation shall be deemed as meeting the flood opening requirements of ASCE 24 provided that the ventilation openings are designed and installed in accordance with ASCE 24.
Natural ventilation of an occupied space shall be through windows, doors, louvers or other openings to the outdoors. The operating mechanism for such openings shall be provided with ready access so that the openings are readily controllable by the building occupants.
[HCD 1] In employee housing, all openable windows in rooms used for living, dining, cooking or sleeping purposes, and toilet and bath buildings, shall be provided and maintained with insect screening.
[HCD 1] Door openings of rooms used for dining, cooking, toilet and bathing facilities in employee housing shall be provided and maintained with insect screening or with solid doors equipped with self-closing devices in lieu thereof, when approved by the enforcement agency.
[HCD 1] The windows, doors, louvers or other approved closeable openings not required by Section 1030 may open into a passive solar energy collector for ventilation required by this section. The area of ventilation openings to the outside of the passive solar energy collector shall be increased to compensate for the openings required by the interior space.
The openable area of the openings to the outdoors shall be not less than 4 percent of the floor area being ventilated.
Where rooms and spaces without openings to the outdoors are ventilated through an adjoining room, the opening to the adjoining room shall be unobstructed and shall have an area of not less than 8 percent of the floor area of the interior room or space, but not less than 25 square feet (2.3 m2). The openable area of the openings to the outdoors shall be based on the total floor area being ventilated.
Exception: Exterior openings required for ventilation shall be allowed to open into a sunroom with thermal isolation or a patio cover provided that the openable area between the sunroom addition or patio cover and the interior room shall have an area of not less than 8 percent of the floor area of the interior room or space, but not less than 20 square feet (1.86 m2). The openable area of the openings to the outdoors shall be based on the total floor area being ventilated.
Where openings below grade provide required natural ventilation, the outside horizontal clear space measured perpendicular to the opening shall be one and one-half times the depth of the opening. The depth of the opening shall be measured from the average adjoining ground level to the bottom of the opening.
Contaminant sources in naturally ventilated spaces shall be removed in accordance with the California Mechanical Code and the California Fire Code.
Rooms containing bathtubs, showers, spas and similar bathing fixtures shall be mechanically ventilated in accordance with the California Mechanical Code.
The minimum exhaust rate shall not be less than that established by Table 403.7 "Minimum Exhaust Rates." See California Mechanical Code, Chapter 5, for additional provisions related to environmental air ducts.
[HCD 1] In addition to the requirements in this section and in the California Mechanical Code, bathrooms in Group R occupancies shall be mechanically ventilated in accordance with the California Green Building Standards Code (CALGreen), Chapter 4, Division 4.5.
Where natural ventilation is to be provided by openings onto yards or courts, such yards or courts shall comply with Section 1205.
Ventilation and exhaust systems for occupancies and operations involving flammable or combustible hazards or other contaminant sources as covered in the California Mechanical Code or the California Fire Code shall be provided as required by both codes.
Interior spaces intended for human occupancy shall be provided with active or passive space heating systems capable of maintaining an indoor temperature of not less than 68°F (20°C) at a point 3 feet (914 mm) above the floor on the design heating day.
Exceptions:
  1. Space heating systems are not required for:
    1. Interior spaces where the primary purpose of the space is not associated with human comfort.
    2. Group F, H, S or U occupancies.
  2. [HCD 1] For limited-density owner-built rural dwellings, a heating facility or appliance shall be installed in each dwelling subject to the provisions of Subchapter 1, Chapter 1, Title 25, California Code of Regulations, commencing with Section 74; however, there shall be no specified requirement for heating capacity or temperature maintenance. The use of solid-fuel or solar-heating devices shall be deemed as complying with the requirements of this section. If nonrenewable fuel is used in these dwellings, rooms so heated shall meet current installation standards.
  3. [OSHPD 1, 1R, 2, 3, 4 & 5] Space heating systems shall comply with the requirements of the California Mechanical Code.
  4. [HCD 1] When a passive solar energy collector is designed as a conditioned area it shall comply with the California Energy Code. Nonconditioned passive solar energy collectors are exempt from compliance with the California Energy Code.
Every space intended for human occupancy shall be provided with natural light by means of exterior glazed openings in accordance with Section 1204.2 or shall be provided with artificial light in accordance with Section 1204.3. Exterior glazed openings shall open directly onto a public way or onto a yard or court in accordance with Section 1205.
[HCD 1] Glazed openings may open into a passive solar energy collector provided the area of exterior glazed openings in the passive solar energy collector is increased to compensate for the area required by the interior space.
The minimum net glazed area shall be not less than 8 percent of the floor area of the room served.
For the purpose of natural lighting, any room is permitted to be considered as a portion of an adjoining room where one-half of the area of the common wall is open and unobstructed and provides an opening of not less than one-tenth of the floor area of the interior room or 25 square feet (2.32 m2), whichever is greater.
Exception: Openings required for natural light shall be permitted to open into a sunroom with thermal isolation or a patio cover where the common wall provides a glazed area of not less than one-tenth of the floor area of the interior room or 20 square feet (1.86 m2), whichever is greater.
Exterior openings required by Section 1204.2 for natural light shall open directly onto a public way, yard or court, as set forth in Section 1205.
Exceptions:
  1. Required exterior openings are permitted to open into a roofed porch where the porch meets all of the following criteria:
    1. Abuts a public way, yard or court.
    2. Has a ceiling height of not less than 7 feet (2134 mm).
    3. Has a longer side at least 65 percent open and unobstructed.
  2. Skylights are not required to open directly onto a public way, yard or court.
Artificial light shall be provided that is adequate to provide an average illumination of 10 footcandles (107 lux) over the area of the room at a height of 30 inches (762 mm) above the floor level.
Stairways within dwelling units and exterior stairways serving a dwelling unit shall have an illumination level on tread runs of not less than 1 footcandle (11 lux). Stairways in other occupancies shall be governed by Chapter 10.