CRC · California Residential Code

What are the required attic access opening size, location and headroom requirements?

If your attic has at least 30 inches of clear vertical height over 30 square feet, the California Residential Code requires an attic access. Provide a rough-framed opening of at least 22 in. by 30 in., place it in a hallway or other readily accessible location, and for ceiling scuttles ensure at least 30 inches of unobstructed headroom in the attic above the opening. (§ R807.1)

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Last reviewed: July 6, 2026

What the code requires — plain English

Buildings with attics that have at least 30 inches of vertical clear height over an area of 30 square feet must provide an attic access. The rough-framed opening must be at least 22 inches by 30 inches, placed in a hallway or other location with ready access; if the access is in a ceiling, there must be at least 30 inches of unobstructed headroom in the attic above the opening on one side or more. These requirements are stated in § R807.1.

The single most important rule: if an attic area has a vertical clear height of 30 in. or more over 30 sq ft, you must provide an access opening sized and located per § R807.1.

Requirements in detail

All quoted dimensions below are minimums required by § R807.1.

How the code decides whether access is required

Measured vertical height: from the top of the ceiling framing members to the underside of the roof framing members. If that vertical height is ≥ 30 in. over an area of ≥ 30 sq ft, the attic must have access. § R807.1.

Minimum opening sizes and location

Minimum rough-framed opening: 22 in. × 30 in. (559 mm × 762 mm).
If the opening is in a wall, it must be at least 22 in. wide × 30 in. high.
The opening must be located in a hallway or other location with ready access (i.e., not concealed or obstructed). § R807.1.

Headroom (ceiling-located access)

Where the access is located in a ceiling, provide unobstructed headroom of not less than 30 in. (762 mm) in the attic at or above the access opening — measured vertically from the bottom of ceiling framing members — along one side or more. § R807.1.

Decision-relevant dimensions (quick reference)

Condition / feature	Required value (minimum)	Code reference
Vertical attic height threshold (when access is required)	30 inches (762 mm)	§ R807.1
Area over which that height must exist	30 square feet (2.8 m²)	§ R807.1
Minimum rough-framed opening (general)	22 in. × 30 in. (559 mm × 762 mm)	§ R807.1
Minimum wall opening (if access in wall)	22 in. wide × 30 in. high	§ R807.1
Minimum headroom above a ceiling access	30 inches (762 mm) unobstructed along one side or more	§ R807.1
Required location	Hallway or other location with ready access (not obstructed)	§ R807.1

Exceptions & special cases

Where mechanical equipment is installed in the attic, additional or different access requirements may apply — see the California Mechanical Code for access requirements for attic-installed equipment (the CRC text points you to the Mechanical Code). § R807.1 notes this cross-reference.
The CRC requirement above is the residential rule. Other model codes (for example, the California Building Code) contain similar but not identical language (CBC §1209.2 uses a 20 in. × 30 in. opening in that context). If you operate in a mixed-jurisdiction or consult multiple codes, confirm which code and edition your project authority enforces.
Access openings may be required to be larger or have additional clearances for servicing large appliances or HVAC components per the Mechanical Code or appliance manufacturer instructions. Check the relevant Mechanical Code sections when equipment is present.

Common mistakes

Confusing which surface to measure: the vertical height is measured from the top of ceiling framing members up to the underside of roof framing members — not from finished ceiling surface or drywall. § R807.1.
Using the smaller 20 in. width found in other codes (CBC) instead of the CRC’s 22 in. requirement — the CRC explicitly requires 22 in. × 30 in. for the rough-framed opening. § R807.1.
Installing the scuttle in an obstructed or hard-to-reach location (e.g., behind built-ins or inside closets) when the code requires “ready access” (a hallway or similarly accessible place). § R807.1.
Assuming the attic must have full 30 in. headroom everywhere; the code requires 30 in. unobstructed headroom along one side or more above a ceiling access, not across the entire attic. § R807.1.

Worked example

Scenario: You are finishing a house attic. Measured from the top of the ceiling joists to the underside of the rafters you find 36 inches of clear vertical space over an area of 45 square feet. You will place a ceiling scuttle.

Step-by-step application:

Does the attic meet the threshold that triggers access?
- Vertical height = 36 in. (≥ 30 in.) over 45 sq ft (≥ 30 sq ft) → access required per § R807.1.
Opening size: provide a rough-framed opening of at least 22 in. × 30 in. (559 mm × 762 mm). § R807.1.
Headroom above the ceiling opening: verify there is at least 30 in. of unobstructed vertical space in the attic above one side of the opening (measured from the bottom of the ceiling framing members). Your attic has 36 in., so it meets the 30 in. headroom requirement. § R807.1.
Location: place the access in a hallway or other readily accessible location, not behind fixed storage or in a locked closet per § R807.1.
If you plan to put HVAC equipment in the attic, check the California Mechanical Code for any larger access or servicing clearances before finalizing the opening.

Related provisions

§ R807.1 — Attic access requirements (primary controlling section for attics).
§ R807 — Section heading and context for attic access within the CRC.
§ CK108.1 — Attics used as evacuation locations: minimum headroom rules in CRC Appendix CK (attic evacuation locations).
See also: § 1209.2 (California Building Code) — comparable attic access language used in the CBC; helpful when consulting mixed-code materials.
See the California Mechanical Code for additional attic access requirements when mechanical equipment is located in attics.

Code references

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

CRC § 8-45 High relevance — show source text

2025 CALIFORNIA RESIDENTIAL CODE 8-45

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

ROOF-CEILING CONSTRUCTION

SECTION R807—ATTIC ACCESS

R807.1 Attic access. Buildings with attics shall have an access opening to attic areas that have a vertical height of 30 inches (762 mm) or greater over an area of not less than 30 square feet (2.8 m [2] ). The vertical height shall be measured from the top of the ceiling framing members to the underside of the roof framing members.

The rough-framed opening shall be not less than 22 inches by 30 inches (559 mm by 762 mm) and shall be located in a hallway or other location with ready access. Where located in a wall, the opening shall be not less than 22 inches wide by 30 inches high (559 mm wide by 762 mm high). Where the access is located in a ceiling, unobstructed headroom in the attic space above the access shall be not less than 30 inches (762 mm) along one side or more measured vertically from the bottom of ceiling framing members. See the California Mechanical Code for access requirements where mechanical equipment is located in attics.

8-46 2025 CALIFORNIA RESIDENTIAL CODE

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

CALIFORNIA RESIDENTIAL CODE – MATRIX ADOPTION TABLE

CHAPTER 9 – ROOF ASSEMBLIES

(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	Col6	Col7	DSA	Col9	Col10	OSHPD	Col12	Col13	Col14	Col15	Col16	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	5	5	5	5	5	5	5	5
Adopt entire chapter
Adopt entire chapter as amended (amended sections listed below)				X
Adopt only those sections that are listed below			X
Chapter / Section
R901.1			X
R902.1 - R902.4			X
R903.4.1				X
R904.1 - R904.4			X
R905.15				X
R905.16				X
R907.

CRC § 8-45 High relevance — show source text
Contributes to but does not supersede the requirements in Section N1102.
b. Alternatively, sufficient continuous 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.|a. Contributes to but does not supersede the requirements in Section N1102.
b. Alternatively, sufficient continuous 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.|

2025 CALIFORNIA RESIDENTIAL CODE 8-45

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

ROOF-CEILING CONSTRUCTION

SECTION R807—ATTIC ACCESS

R807.1 Attic access. Buildings with attics shall have an access opening to attic areas that have a vertical height of 30 inches (762 mm) or greater over an area of not less than 30 square feet (2.8 m [2] ). The vertical height shall be measured from the top of the ceiling framing members to the underside of the roof framing members.

The rough-framed opening shall be not less than 22 inches by 30 inches (559 mm by 762 mm) and shall be located in a hallway or other location with ready access. Where located in a wall, the opening shall be not less than 22 inches wide by 30 inches high (559 mm wide by 762 mm high). Where the access is located in a ceiling, unobstructed headroom in the attic space above the access shall be not less than 30 inches (762 mm) along one side or more measured vertically from the bottom of ceiling framing members. See the California Mechanical Code for access requirements where mechanical equipment is located in attics.

8-46 2025 CALIFORNIA RESIDENTIAL CODE

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

CALIFORNIA RESIDENTIAL CODE – MATRIX ADOPTION TABLE

CHAPTER 9 – ROOF ASSEMBLIES

(Matrix Adoption Tables are nonregulatory, intended only as an aid to the code user. See Chapter 1 for state agency authority and building applications.)
CRC § 1209.1 High relevance — show source text
1209.1 Crawl spaces. Crawl spaces shall be provided with not less than one access opening that shall be not less than 18 inches by 24 inches (457 mm by 610 mm).

1209.1.1 [SPCB] Accessible under-floor areas shall be provided with an 18-inch by 24-inch (457 mm by 610 mm) access crawl hole. Pipes, ducts and other nonstructural construction shall not interfere with the accessibility to or within under-floor areas.

1209.2 Attic spaces. An opening not less than 20 inches by 30 inches (559 mm by 762 mm) shall be provided to any attic area having a clear height of over 30 inches (762 mm). Clear headroom of not less than 30 inches (762 mm) shall be provided in the attic space at or above the access opening.

1209.3 Mechanical appliances. Access to mechanical appliances installed in under-floor areas, in attic spaces and on roofs or elevated structures shall be in accordance with the California Mechanical Code .

SECTION 1210—TOILET AND BATHROOM REQUIREMENTS

[P] 1210.1 Required fixtures. The number and type of plumbing fixtures provided in any occupancy shall comply with the California Plumbing Code.

[P] 1210.2 Finish materials. Walls, floors and partitions in toilet and bathrooms shall comply with Sections 1210.2.1 through 1210.2.5.

[OSHPD 1, 2, 3 & 5] Facilities subject to OSHPD 1, 2, 3 & 5 shall also comply with Section 1224.4.11.

[OSHPD 4] Facilities subject to OSHPD 4 shall also comply with Section 1227.9.

[P] 1210.2.1 Floors and wall bases. In other than dwelling units, toilet, bathing and shower room floor finish materials shall have a smooth, hard, nonabsorbent surface. The intersections of such floors with walls shall have a smooth, hard, nonabsorbent vertical base that extends upward onto the walls not less than 4 inches (102 mm).

[P] 1210.2.2 Walls and partitions. Walls and partitions within 2 feet (610 mm) of service sinks, urinals and water closets shall have a smooth, hard, nonabsorbent surface, to a height of not less than 4 feet (1219 mm) above the floor, and except for structural elements, the materials used in such walls shall be of a type that is not adversely affected by moisture.

Exception: This section does not apply to the following buildings and spaces:
1. Dwelling units and sleeping units.
2. Toilet rooms that are not for use by the general public and that have not more than one water closet.
Accessories such as grab bars, towel bars, paper dispensers and soap dishes, provided on or within walls, shall be installed and sealed to protect structural elements from moisture.

1210.2.3 Adult changing table surround. Walls and partitions within 2 feet (610 mm) measured horizontally from each end of the adult changing table and to a height of not less than 72 inches (1829 mm) above the floor shall have a smooth, hard, nonabsorbent surface, and except for structural elements, the materials used in such walls shall be of a type that is not adversely affected by moisture.
CRC § 1208.2.1 High relevance — show source text
1208.2.1 Furred ceiling. Any room with a furred ceiling shall be required to have the minimum ceiling height in two-thirds of the area thereof, but in no case shall the height of the furred ceiling be less than 7 feet (2134 mm). 1208.3 Dwelling unit size. Dwelling units shall have a minimum of 190 square feet (17.7 m [2] ) of habitable space. 1208.4 Room area. Every dwelling unit shall have not less than one room that shall have not less than 120 square feet (11.2 m [2] ) of net floor area. Sleeping units and other habitable rooms of a dwelling unit shall have a net floor area of not less than 70 square feet (6.5 m [2] ).

Exception: Kitchens are not required to be of a minimum floor area.

1208.5 Efficiency dwelling units. [HCD 1] Unless modified by local ordinance pursuant to Health and Safety Code Section 17958.1, effi- ciency dwelling units shall comply with the following:
1. The unit’s habitable space shall comply with Sections 1208.1 through 1208.4.
2. The unit shall be provided with a separate closet.
3. For other than Accessible, adaptable dwelling units, the unit shall be provided with a kitchen sink, cooking appliance and refrigerator, each having a clear working space of not less than 30 inches (762 mm) in front. Light and ventilation conforming to this code shall be provided.
4. The unit shall be provided with a separate bathroom containing a water closet, lavatory and bathtub or shower.
SECTION 1209—ACCESS TO UNOCCUPIED SPACES

1209.1 Crawl spaces. Crawl spaces shall be provided with not less than one access opening that shall be not less than 18 inches by 24 inches (457 mm by 610 mm).

1209.1.1 [SPCB] Accessible under-floor areas shall be provided with an 18-inch by 24-inch (457 mm by 610 mm) access crawl hole. Pipes, ducts and other nonstructural construction shall not interfere with the accessibility to or within under-floor areas.

1209.2 Attic spaces. An opening not less than 20 inches by 30 inches (559 mm by 762 mm) shall be provided to any attic area having a clear height of over 30 inches (762 mm). Clear headroom of not less than 30 inches (762 mm) shall be provided in the attic space at or above the access opening.

1209.3 Mechanical appliances. Access to mechanical appliances installed in under-floor areas, in attic spaces and on roofs or elevated structures shall be in accordance with the California Mechanical Code .

SECTION 1210—TOILET AND BATHROOM REQUIREMENTS

[P] 1210.1 Required fixtures. The number and type of plumbing fixtures provided in any occupancy shall comply with the California Plumbing Code.

[P] 1210.2 Finish materials. Walls, floors and partitions in toilet and bathrooms shall comply with Sections 1210.2.1 through 1210.2.5.

[OSHPD 1, 2, 3 & 5] Facilities subject to OSHPD 1, 2, 3 & 5 shall also comply with Section 1224.4.11.
CRC § 0.30 High relevance — show source text
1. Guards per Section 1013 if a rooftop platform is provided; or

2. A railing that is 12 inches (305 mm) in height if a sloped roof is provided.

K107.6 Utility/equipment buffer zone. A separation of 48 inches shall be provided between a rooftop evacuation location and any mechanical equipment, photovoltaic system, utility service drop or other utility line. Electrical service lines shall not pass over evacua- tion locations.

SECTION K108 — ATTICS THAT ARE EVACUATION LOCATIONS

K108.1 General. Attics that have finish floors no less than one (1) foot (0.30 meter) above the WSEL200 shall be permitted to be evacua- tion locations.

K108.2 Headroom. When an attic is used as an evacuation location, the minimum headroom of the required area shall be 30 inches (762 mm) with 50 percent of the required area having a headroom of 60 inches (1524 mm).

K108.3 Attic flooring. The required area of the evacuation location shall be solidly sheathed.

K108.4 Attic live loads. Attic areas that are used as evacuation locations shall be designed for the floor live load required for the occu- pancy as required in Table 1607.2.

K108.5 Evacuation routes to attic evacuation locations. Evacuation routes to attic evacuation locations shall be permitted to be provided by a stairway, ramp, alternating tread device, fixed ladder or other means approved by the building official.

Exception: In Group R-3.1 occupancies that are subject to the requirements of Chapter 11A or 11B, such requirements shall apply to the evacuation routes to attics.

K108.6 Means of escape from attics. The means of escape from attics shall comply with Section K105.

SECTION K109 — ALTERNATE MEANS OF PROTECTION

K109.1 Request for approval of alternate means of protection. Requests for approval to use an alternative means of protection shall be made in writing to the building official by the owner or the owner’s authorized representative. The request shall be accompanied by a full statement of the conditions and sufficient evidence that the proposed alternate means of protection provides reasonable protection to occupants. The building official shall require the owner to obtain a written statement from the applicable emergency management authority regarding plans and processes related to notification of anticipated conditions of flooding, warnings, evacuations and other pertinent conditions relative to the proximity of nearby levees. The building official shall also require the owner to obtain a written state- ment and findings from the entity that has jurisdiction over the management, maintenance, monitoring and control of flood protection works in the vicinity of the location of the owner’s property; such statement shall comment on the viability of the proposed alternate means of protection. The building official may request written statements from the Central Valley Flood Protection Board, the California Department of Water Resources, and the California Emergency Management Agency.

Approval of a request for use of an alternative means of protection made pursuant to these provisions shall be limited to the particu- lar case covered by the request and shall not be construed as establishing any precedent for any future request except in substantially equivalent situations.
CRC § 3.1 High relevance — show source text
K107.2 Rooftop platforms required. A rooftop platform shall be provided if the roof covering materials are:

1. Clay tile, concrete tile, slate shingles, wood shingles or wood shakes, and the roof slope is three units vertical in 12 units hori- zontal (25 percent slope) or greater.

2025 CALIFORNIA BUILDING CODE APPENDIX K-3

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APPENDIX K—GROUP R-3 AND GROUP R-3.1 OCCUPANCIES PROTECTED BY THE FACILITIES OF THE CENTRAL VALLEY FLOOD PROTECTION PLAN

2. Metal roof panels or metal roof shingles, and the roof slope is one unit vertical in 12 units horizontal (8.33 percent slope) or greater.

K107.3 Roof live loads. Roof areas that are rooftop evacuation locations and roofs that support rooftop platforms that are evacuation locations shall be designed for the roof live load required for the occupancy as required in Table 1607.2.

K107.4 Evacuation routes to rooftop evacuation locations. Evacuation routes to rooftop evacuation locations shall be permitted to be provided by a stairway, ramp, alternating tread device, fixed ladder or other means approved by the building official.

Exception: In Group R-3.1 occupancies that are subject to the requirements of Chapter 11A or 11B, such requirements shall apply to the evacuation routes to rooftops.

K107.5 Perimeter protection. For Group R-3 and R-3.1 occupancies, the perimeter of rooftop evacuation locations shall be protected by:

1. Guards per Section 1013 if a rooftop platform is provided; or

2. A railing that is 12 inches (305 mm) in height if a sloped roof is provided.

K107.6 Utility/equipment buffer zone. A separation of 48 inches shall be provided between a rooftop evacuation location and any mechanical equipment, photovoltaic system, utility service drop or other utility line. Electrical service lines shall not pass over evacua- tion locations.

SECTION K108 — ATTICS THAT ARE EVACUATION LOCATIONS

K108.1 General. Attics that have finish floors no less than one (1) foot (0.30 meter) above the WSEL200 shall be permitted to be evacua- tion locations.

K108.2 Headroom. When an attic is used as an evacuation location, the minimum headroom of the required area shall be 30 inches (762 mm) with 50 percent of the required area having a headroom of 60 inches (1524 mm).

K108.3 Attic flooring. The required area of the evacuation location shall be solidly sheathed.

K108.4 Attic live loads. Attic areas that are used as evacuation locations shall be designed for the floor live load required for the occu- pancy as required in Table 1607.2.

K108.5 Evacuation routes to attic evacuation locations. Evacuation routes to attic evacuation locations shall be permitted to be provided by a stairway, ramp, alternating tread device, fixed ladder or other means approved by the building official.
CRC § 0.30 High relevance — show source text
CK107 Rooftop evacuation locations. Rooftop evacuation locations shall be permitted to include rooftop platforms and rooftop areas provided that they are no less than one (1) foot (0.30 meter) above the WSEL200. A minimum horizontal distance of 3 feet (0.91 meter) shall be provided between the lower edge of the rooftop evacuation location access point and the evacuation location lower perimeter.

CK107.1 Rooftop platforms required. A rooftop platform shall be provided if the roof covering materials are: 1. Clay tile, concrete tile, slate shingles, wood shingles or wood shakes and the roof slope is three units vertical in 12 units hori- zontal (25 percent slope) or greater. 2. Metal roof panels or metal roof shingles and the roof slope is one unit vertical in 12 units horizontal (8.33 percent slope) or greater.

CK107.2 Roof live loads. Roof areas that are rooftop evacuation locations and roofs that support rooftop platforms that are evacua- tion locations shall be designed for the roof live load required for the occupancy as required in CBC Table 1607.2.

CK107.3 Evacuation routes to rooftop evacuation locations. Evacuation routes to rooftop evacuation locations shall be permitted to be provided by a stairway, ramp, alternating tread device, fixed ladder or other means approved by the building official.

APPENDIX CK-4 2025 CALIFORNIA RESIDENTIAL CODE

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APPENDIX CK — AREAS PROTECTED BY THE FACILITIES OF THE CENTRAL VALLEY FLOOD PROTECTION PLAN

CK107.4 Perimeter protection. The perimeter of rooftop evacuation locations shall be protected by:

1. Guards per Section R312 if a rooftop platform is provided; or

2. A railing that is 12 inches (305 mm) in height if a sloped roof is provided.

CK107.5 Utility/equipment buffer zone. A separation of 48 inches shall be provided between an evacuation location and any mechanical equipment, photovoltaic system, utility service drop or other utility line. Electrical service lines shall not pass over evacu- ation locations.

CK108 Attics that are evacuation locations. Attics that have finish floors no less than one (1) foot above the WSEL200 shall be permitted to be evacuation locations.

CK108.1 Headroom. When an attic is used as an evacuation location, the minimum headroom of the required area shall be 30 inches (762 mm) with 50 percent of the required area having a headroom of 60 inches (1524 mm).

CK108.2 Attic flooring. The required area of the evacuation location shall be solidly sheathed.

CK108.3 Attic live loads. Attic areas that are used as evacuation locations shall be designed for the attic with limited live load requirement in Table R301.5.
CRC § 3.1 High relevance — show source text
APPENDIX CK-4 2025 CALIFORNIA RESIDENTIAL CODE

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APPENDIX CK — AREAS PROTECTED BY THE FACILITIES OF THE CENTRAL VALLEY FLOOD PROTECTION PLAN

CK107.4 Perimeter protection. The perimeter of rooftop evacuation locations shall be protected by:

1. Guards per Section R312 if a rooftop platform is provided; or

2. A railing that is 12 inches (305 mm) in height if a sloped roof is provided.

CK107.5 Utility/equipment buffer zone. A separation of 48 inches shall be provided between an evacuation location and any mechanical equipment, photovoltaic system, utility service drop or other utility line. Electrical service lines shall not pass over evacu- ation locations.

CK108 Attics that are evacuation locations. Attics that have finish floors no less than one (1) foot above the WSEL200 shall be permitted to be evacuation locations.

CK108.1 Headroom. When an attic is used as an evacuation location, the minimum headroom of the required area shall be 30 inches (762 mm) with 50 percent of the required area having a headroom of 60 inches (1524 mm).

CK108.2 Attic flooring. The required area of the evacuation location shall be solidly sheathed.

CK108.3 Attic live loads. Attic areas that are used as evacuation locations shall be designed for the attic with limited live load requirement in Table R301.5.

CK108.4 Evacuation routes to attic evacuation locations. In Group R-3.1 occupancies that are subject to the requirements of Chap- ter 11A or 11B, such requirements shall apply to the evacuation routes to attics. In Group R-3 occupancies, evacuation routes to attic evacuation locations shall be permitted to be provided by a stairway, ramp, alternating tread device, fixed ladder or other means approved by the building official.

CK108.5 Means of escape from attics. The means of escape from attics shall comply with Section CK105.

CK109 Alternate means of protection.

CK109.1 Request for approval of alternate means of protection. Requests for approval to use an alternative means of protection shall be made in writing to the building official by the owner or the owner’s authorized representative. The request shall be accompa- nied by a full statement of the conditions and sufficient evidence that the proposed alternate means of protection provides reasonable protection to occupants. The building official shall require the owner to obtain a written statement from the applicable emergency management authority regarding plans and processes related to notification of anticipated conditions of flooding, warn- ings, evacuations and other pertinent conditions relative to the proximity of nearby levees. The building official shall also require the owner to obtain a written statement and findings from the entity that has jurisdiction over the management, maintenance, monitor- ing and control of flood protection works in the vicinity of the location of the owner’s property, such statement shall comment on the viability of the proposed alternate means of protection. The building official may request written statements from the Central Valley Flood Protection Board, the California Department of Water Resources and the California Emergency Management Agency.
CRC § 701.6.2 High relevance — show source text
The opening shall directly communicate with the outdoors or shall communicate through a vertical or horizontal duct to the outdoors or spaces that freely communicate with the outdoors (see Figure 701.6.2) and shall have a minimum free area of the following: (1) One square inch per 3000 Btu/h (0.0007 m [2] /kW) of the total input rating of all appliances located in the enclosure.

(2) Not less than the sum of the areas of all vent connectors in the space. [NFPA 54:9.3.3.2] 701.7 Combination Indoor and Outdoor Combustion Air. The use of a combination of indoor and outdoor com bustion air shall be in accordance with Section 701.7.1 through Section 701.7.3. [NFPA 54:9.3.4] (see Appendix F for example calculations)

FIGURE 701.6.1(1) ALL COMBUSTION AIR FROM OUTDOORS – INLET

AIR FROM VENTILATED CRAWL SPACE AND OUTLET AIR TO

VENTILATED ATTIC

[NFPA 54: FIGURE A.9.3.3.1(1)(a)]

FIGURE 701.6.1(2)

ALL COMBUSTION AIR FROM OUTDOORS

THROUGH VENTILATED ATTIC

[NFPA 54: FIGURE A.9.3.3.1(1)(b)]

148 2025 CALIFORNIA MECHANICAL CODE

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

COMBUSTION AIR

FIGURE 701.6.1(3) ALL COMBUSTION AIR FROM OUTDOORS

THROUGH HORIZONTAL DUCTS

[NFPA 54: FIGURE A.9.3.3.1(2)]

FIGURE 701.6.2

ALL COMBUSTION AIR FROM OUTDOORS THROUGH

SINGLE COMBUSTION AIR OPENING

[NFPA 54: FIGURE A.9.3.3.2]

701.7.1 Indoor Openings. Where used, openings connecting the interior spaces shall comply with Section 701.5. [NFPA 54:9.3.4(1)]

701.7.2 Outdoor Opening(s) Location. Outdoor opening(s) shall be located in accordance with Section 701.6. [NFPA 54:9.3.4(2)]

701.7.3 Outdoor Opening(s) Size. The outdoor opening(s) size shall be calculated in accordance with the following:

(1) The ratio of the interior spaces shall be the available volume of all communicating spaces divided by the required volume.

(2) The outdoor size reduction factor shall be 1 minus the ratio of interior spaces.

(3) The minimum size of outdoor opening(s) shall be the full size of outdoor opening(s) calculated in accordance with Section 701.6, multiplied by the reduction factor. The minimum dimension of air openings shall not be less than 3 inches (76 mm).
CRC § 2-550 Medium relevance — show source text
″|3′-2″|4′-3″|3′-8″|3′-1″|2′-7″|2′-0″| |2-550S162-68|6′-5″|5′-10″|5′-3″|4′-9″|4′-4″|5′-5″|4′-9″|4′-3″|3′-9″|3′-4″| |2-800S162-33|—|—|—|—|—|—|—|—|—|—| |2-800S162-43|2′-6″|—|—|—|—|—|—|—|—|—| |2-800S162-54|6′-1″|5′-5″|4′-10″|4′-3″|3′-9″|4′-11″|4′-3″|3′-8″|3′-0″|2′-5″| |2-800S162-68|7′-8″|6′-11″|6′-3″|5′-9″|5′-2″|6′-5″|5′-9″|5′-1″|4′-6″|4′-0″| |2-1000S162-43|2′-10″|—|—|—|—|—|—|—|—|—| |2-1000S162-54|6′-7″|5′-10″|5′-3″|4′-9″|4′-3″|5′-4″|4′-9″|4′-1″|3′-5″|2′-9″| |2-1000S162-68|8′-8″|7′-10″|7′-2″|6′-6″|5′-11″|7′-4″|6′-6″|5′-9″|5′-1″|4′-6″| |2-1200S162-54|5′-6″|4′-10″|4′-4″|3′-11″|3′-7″|4′-5″|3′-11″|3′-6″|3′-2″|2′-11″| |2-1200S162-68|9′-7″|8′-8″|7′-11″|7′-2″|6′-6″|8′-1″|7′-2″|6′-4″|5′-8″|5′-0″| |For SI: 1 mil = 0.0254 mm, 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa, 1 pound per square inch = 6.895 kPa, 1 ksi = 1,000 psi = 6.895 MPa.
a.
CRC § 1105.3 Medium relevance — show source text
(1) The addition of a second refrigerant is allowed by the equipment manufacturer and is in accordance with the manufacturer’s instructions.

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230 2025 CALIFORNIA MECHANICAL CODE

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

REFRIGERATION

A compressor or portion of a condensing unit supported from the ground shall rest on a concrete or other approved base extending not less than 3 inches (76 mm) above the adjoining ground level.

1105.3 Access. An unobstructed readily accessible opening and passageway not less than 36 inches (914 mm) in width and 80 inches (2032 mm) in height shall be provided and maintained to the compressor, valves required by this chapter, or other portions of the system requiring routine maintenance.

Exceptions:

(1) Refrigerant evaporators, suspended overhead, shall be permitted to use portable means of access.

(2) Air filters, brine control or stop valves, fan motors or drives, and remotely de-energized electrical connections shall be permitted to be provided access to an unobstructed space not less than 30 inches (762 mm) in depth, width, and height. Where an access opening is immediately adjacent to these items and the equipment is capable of being serviced, repaired, and replaced from this opening, the dimensions shall be permitted to be reduced to 22 inches (559 mm) by 30 inches (762 mm) provided the largest piece of equipment is removed through the opening.

(3) Cooling equipment, using Group A1 refrigerants or brine, located in an attic or furred space shall be permitted to be provided access by a minimum opening and passageway thereto of not less than 22 inches (559 mm) by 30 inches (762 mm).

(4) Cooling or refrigeration equipment, using Group A1 or B1 refrigerants or brine, located on a roof or on an exterior wall of a building, shall be permitted to be provided access as for furnaces in Section 304.3.

1105.4 Illumination and Service Receptacles. In addition to the requirements of Section 301.4, permanent luminaires shall be installed for equipment required by this code to be accessible or readily accessible. Such luminaires shall provide illumination to perform the required tasks for which access is provided. Control of the illumination source shall be provided at the access entrance.

Exceptions:

(1) Luminaires shall be permitted to be omitted where the fixed lighting of the building will provide the required illumination.

(2) Equipment located on the roof or on the exterior walls of a building.

1105.5 Ventilation of Rooms Containing Condensing Units. Where not in a refrigerant machinery room, rooms or spaces in which a refrigerant-containing portion of a condensing unit is installed shall be provided with ventilation in accordance with Section 1105.5.1 or Section 1105.5.2. Ventilation for machinery rooms shall comply with Section 1106.0.

1105.5.1 Permanent Gravity Ventilation Open- ings. Permanent gravity ventilation openings of not less

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(2) The resulting mixture does not change the refrigerant safety group. [ASHRAE 15:7.5.1.7]
CRC § 6.98 Medium relevance — show source text
13|6.98|2.42| |30|15|12:12|5.61|6.10|7.16|8.31|9.54|10.85|2.93| |30|30|< 1:12|1.84|2.01|2.35|2.73|3.13|3.57|1.93| |30|30|5:12|2.56|2.78|3.27|3.79|4.35|4.95|2.75| |30|30|7:12|4.92|5.35|6.28|7.29|8.37|9.52|3.12| |30|30|12:12|8.92|9.71|11.39|13.22|15.17|17.26|4.14| |30|45|< 1:12|1.84|2.01|2.35|2.73|3.13|3.57|2.03| |30|45|5:12|2.56|2.78|3.27|3.79|4.35|4.95|3.26| |30|45|7:12|6.23|6.78|7.96|9.23|10.60|12.06|3.82| |30|45|12:12|12.23|13.31|15.63|18.12|20.80|23.67|5.36| |30|60|< 1:12|1.84|2.01|2.35|2.73|3.13|3.57|2.14| |30|60|5:12|2.56|2.78|3.27|3.79|4.35|4.95|3.78| |30|60|7:12|7.54|8.21|9.64|11.17|12.83|14.60|4.52| |30|60|12:12|15.54|16.92|19.86|23.03|26.44|30.08|6.57| |60|15|< 1:12|3.42|3.72|4.36|5.06|5.81|6.61|3.63| |60|15|5:12|4.75|5.17|6.06|7.03|8.07|9.19|4.40| |60|15|7:12|6.76|7.36|8.64|10.02|11.51|13.09|4.75| |60|15|12:12|10.35|11.27|13.23|15.34|17.61|20.04|5.71| |60|30|< 1:12|3.42|3.72|4.36|5.06|5.81|6.61|3.83| |60|30|5:12|4.75|5.17|6.06|7.03|8.07|9.19|5.37| |60|30|7:12|9.12|9.93|11.66|13.52|15.52|17.66|6.07| |60|30|12:12|16.30|17.75|20.83|24.16|27.73|31.55|8.

Frequently asked questions

Do I always need an attic access if my attic is shallow?

If the attic has less than 30 in. vertical height over a 30 sq ft area, CRC § R807.1 does not require access. But if any portion meets or exceeds those thresholds, access is required.

Can the attic access be located in a bedroom closet?

No — § R807.1 requires the opening be located in a hallway or other location with ready access. A bedroom closet could be considered obstructed or not “ready access”; consult your enforcing agency.

If mechanical equipment is in the attic, do I still follow R807.1 only?

No — § R807.1 directs you to the California Mechanical Code for equipment-specific access requirements; mechanical rules may require larger openings, access platforms, clearances or service lighting.

Is the minimum opening measured rough-framed or finished?

The code states the rough-framed opening minimum is 22 in. × 30 in. for CRC § R807.1, so provide that rough frame size before finish.

What if my local jurisdiction enforces the Building Code instead?

The California Building Code (CBC) contains similar attic access language (CBC § 1209.2) with slightly different numeric phrasing in some editions. Always verify which code edition and chapter your local jurisdiction enforces.

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