What are the requirements for under‑floor (crawlspace) access, ventilation and clearances?

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

• CRC § 2.1. High relevance — show source text

  Exceptions:

  1. The total area of ventilation openings shall be permitted to be reduced to [1] / 1,500 of the under-floor area where the ground surface is covered with an approved Class I vapor retarder material.
  2. Where the ground surface is covered with an approved Class 1 vapor retarder material, ventilation openings are not required to be within 3 feet (915 mm) of each external corner of the under-floor space provided that the openings are placed to provide cross ventilation of the space.

  R408.3 Unvented crawl space. For unvented under-floor spaces, the following items shall be provided:

  1. Exposed earth shall be covered with a continuous Class I vapor retarder. Joints of the vapor retarder shall overlap by 6 inches (152 mm) and shall be sealed or taped. The edges of the vapor retarder shall extend not less than 6 inches (152 mm) up the stem wall and shall be attached and sealed to the stem wall or insulation.
  2. One of the following shall be provided for the under-floor space: 2.1. Continuously operated mechanical exhaust ventilation at a rate equal to 1 cubic foot per minute (0.47 L/s) for each 50 square feet (4.7 m [2] ) of crawl space floor area, including an air pathway to the common area (such as a duct or transfer grille). 2.2. Conditioned air supply sized to deliver at a rate equal to 1 cubic foot per minute (0.47 L/s) for each 50 square feet (4.7 m [2] ) of under-floor area, including a return air pathway to the common area (such as a duct or transfer grille). 2.3. Plenum in existing structures complying with the California Mechanical Code, if under-floor space is used as a plenum. 2.4. Dehumidification sized in accordance with manufacturer’s specifications.

  R408.4 Access. Access shall be provided to all under-floor spaces. Access openings through the floor shall be not smaller than 18 inches by 24 inches (457 mm by 610 mm). Openings through a perimeter wall shall be not less than 16 inches by 24 inches (407 mm by 610 mm). Where any portion of the through-wall access is below grade, an areaway not less than 16 inches by 24 inches (407 mm by 610 mm) shall be provided. The bottom of the areaway shall be below the threshold of the access opening. Through wall access openings shall not be located under a door to the residence. See California Mechanical Code for access requirements where mechanical equipment is located under floors.

  R408.5 Removal of debris. The under-floor grade shall be cleaned of all vegetation and organic material. Wood forms used for placing concrete shall be removed before a building is occupied or used for any purpose. Construction materials shall be removed before a building is occupied or used for any purpose.

  R408.6 Finished grade. The finished grade of under-floor surface shall be permitted to be located at the bottom of the footings; however, where there is evidence that the groundwater table can rise to within 6 inches (152 mm) of the finished floor at the building perimeter or where there is evidence that the surface water does not readily drain from the building site, the grade in the under-floor space shall be as high as the outside finished grade, unless an approved drainage system is provided.

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  FOUNDATIONS

• CRC § 0.0929 High relevance — show source text

  Exception: In Seismic Design Categories A, B and C, columns not more than 48 inches (1219 mm) in height on a pier or footing are exempt from the bottom end lateral displacement requirement within under-floor areas enclosed by a continuous foundation.

  SECTION R408—UNDER-FLOOR SPACE

  R408.1 Moisture control. The under-floor space between the bottom of the floor joists and the earth under any building (except space occupied by a basement) shall comply with Section R408.2 or R408.3.

  R408.2 Openings for under-floor ventilation. Ventilation openings through foundation or exterior walls surrounding the underfloor space shall be provided in accordance with this section. The minimum net area of ventilation openings shall be not less than 1 square foot (0.0929 m [2] ) for each 150 square feet (14 m [2] ) of under-floor area. One ventilation opening shall be within 3 feet (915 mm) of each external corner of the under-floor space. 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 not exceed [1] / 4 inch (6.4 mm), and operational louvers are permitted:

  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 grill or grating.
  4. Extruded load-bearing brick vents.
  5. Hardware cloth of 0.035 inch (0.89 mm) wire or heavier.
  6. Corrosion-resistant wire mesh, with the least dimension being [1] / 8 inch (3.2 mm) thick.

  Exceptions:

  1. The total area of ventilation openings shall be permitted to be reduced to [1] / 1,500 of the under-floor area where the ground surface is covered with an approved Class I vapor retarder material.
  2. Where the ground surface is covered with an approved Class 1 vapor retarder material, ventilation openings are not required to be within 3 feet (915 mm) of each external corner of the under-floor space provided that the openings are placed to provide cross ventilation of the space.

  R408.3 Unvented crawl space. For unvented under-floor spaces, the following items shall be provided:

  1. Exposed earth shall be covered with a continuous Class I vapor retarder. Joints of the vapor retarder shall overlap by 6 inches (152 mm) and shall be sealed or taped. The edges of the vapor retarder shall extend not less than 6 inches (152 mm) up the stem wall and shall be attached and sealed to the stem wall or insulation.
  2. One of the following shall be provided for the under-floor space: 2.1. Continuously operated mechanical exhaust ventilation at a rate equal to 1 cubic foot per minute (0.47 L/s) for each 50 square feet (4.7 m [2] ) of crawl space floor area, including an air pathway to the common area (such as a duct or transfer grille). 2.2. Conditioned air supply sized to deliver at a rate equal to 1 cubic foot per minute (0.47 L/s) for each 50 square feet (4.7 m [2] ) of under-floor area, including a return air pathway to the common area (such as a duct or transfer grille). 2.3. Plenum in existing structures complying with the California Mechanical Code, if under-floor space is used as a plenum.
• CRC § 0.037. High relevance — show source text

  In wood framed assemblies, compliance with U -factors may be demonstrated by installing wall insulation with an R -value of R-15 in 2x4 assemblies, and R-21 in 2x6 assemblies with 16 inches on center spacing.

  (d) Raised-floor insulation. Raised floors separating conditioned space from unconditioned space or ambient air shall have an overall assembly U -factor not exceeding U-0.037. In a wood framed assembly, compliance with the U -factor may be demonstrated by installing insulation with an R -value of 19 or greater.

  Exception to Section 150.0(d): A building with a controlled ventilation or unvented crawlspace may omit raised floor insulation if all of the following are met: i. The foundation walls are insulated to meet the wall insulation minimums as shown in Table 150.1-A; and

  ii. A Class I or Class II vapor retarder is placed over the entire floor of the crawl space; and iii. Vents between the crawlspace and outside air are fitted with automatically operated louvers that are temperature actuated; and

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  SINGLE-FAMILY RESIDENTIAL BUILDINGS— MANDATORY FEATURES AND DEVICES

  iv. The requirements in Reference Residential Appendix RA4.5.1.

  (e) Installation of fireplaces, decorative gas appliances and gas logs. If a masonry or factory-built fireplace is installed, it shall comply with Section 110.5, Section 4.503 of Part 11, and shall have the following:

  1. Closable metal or glass doors covering the entire opening of the firebox; and
  2. A combustion air intake to draw air from the outside of the building, which is at least 6 square inches in area and is equipped with a readily accessible, operable and tight-fitting damper or combustion-air control device; and Exception to Section 150.0(e)2: An outside combustion-air intake is not required if the fireplace will be installed over concrete slab flooring and the fireplace will not be located on an exterior wall.
  3. A flue damper with a readily accessible control. Exception to Section 150.0(e)3: When a gas log, log lighter or decorative gas appliance is installed in a fireplace, the flue damper shall be blocked open if required by the CMC or the manufacturer’s installation instructions.

  (f) Slab edge insulation. Material used for slab edge insulation shall meet the following minimum specifications:

  1. Water absorption rate for the insulation material alone without facings no greater than 0.3 percent when tested in accordance with Test Method A – 24-Hour-Immersion of ASTM C272.

  2. Water vapor permeance no greater than 2.0 perm/inch when tested in accordance with ASTM E96.

  3. Concrete slab perimeter insulation shall be protected from physical damage and ultraviolet light deterioration.

  4. Insulation for a heated slab floor shall meet the requirements of Section 110.8(g).

  (g) Vapor retarder.

  1. In Climate Zones 1–16, the earth floor of unvented crawl space shall be covered with a Class I or Class II vapor retarder. This requirement shall also apply to controlled ventilation crawl space for buildings complying with the Exception to Section 150.0(d).
• CRC § 3.4 High relevance — show source text

  R406.3.4 Backfill. The remainder of the excavated area shall be backfilled with the same type of soil as was removed during the excavation.

  R406.4 Precast concrete foundation system dampproofing. Except where required by Section R406.2 to be waterproofed, precast concrete foundation walls enclosing habitable or useable spaces located below grade shall be dampproofed in accordance with Section R406.1.

  R406.4.1 Panel joints sealed. Precast concrete foundation panel joints shall be sealed full height with a sealant meeting ASTM C920, Type S or M, Grade NS, Class 25, Use NT, M or A. Joint sealant shall be installed in accordance with the manufacturer’s instructions.

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  FOUNDATIONS

  SECTION R407—COLUMNS

  R407.1 Wood column protection. Wood columns shall be protected against decay as set forth in Section R304.

  R407.2 Steel column protection. All surfaces (inside and outside) of steel columns shall be given a shop coat of rust-inhibitive paint, except for corrosion-resistant steel and steel treated with coatings to provide corrosion resistance.

  R407.3 Structural requirements. The columns shall be restrained to prevent lateral displacement at the bottom end. Wood columns shall be not less in nominal size than 4 inches by 4 inches (102 mm by 102 mm). Steel columns shall be not less than 3-inchdiameter (76 mm) Schedule 40 pipe manufactured in accordance with ASTM A53/A53M Grade B or approved equivalent.

  Exception: In Seismic Design Categories A, B and C, columns not more than 48 inches (1219 mm) in height on a pier or footing are exempt from the bottom end lateral displacement requirement within under-floor areas enclosed by a continuous foundation.

  SECTION R408—UNDER-FLOOR SPACE

  R408.1 Moisture control. The under-floor space between the bottom of the floor joists and the earth under any building (except space occupied by a basement) shall comply with Section R408.2 or R408.3.

  R408.2 Openings for under-floor ventilation. Ventilation openings through foundation or exterior walls surrounding the underfloor space shall be provided in accordance with this section. The minimum net area of ventilation openings shall be not less than 1 square foot (0.0929 m [2] ) for each 150 square feet (14 m [2] ) of under-floor area. One ventilation opening shall be within 3 feet (915 mm) of each external corner of the under-floor space. 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 not exceed [1] / 4 inch (6.4 mm), and operational louvers are permitted:

  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 grill or grating.
  4. Extruded load-bearing brick vents.
  5. Hardware cloth of 0.035 inch (0.89 mm) wire or heavier.
  6. Corrosion-resistant wire mesh, with the least dimension being [1] / 8 inch (3.2 mm) thick.
• CRC § 110.7 High relevance — show source text

  3. Attic access doors shall have permanently attached insulation using adhesive or mechanical fasteners. The attic access shall be gasketed to prevent air leakage; and
  4. Insulation shall be installed in direct contact with a roof or ceiling which is sealed to limit infiltration and exfiltration as specified in Section 110.7, including but not limited to placing insulation either above or below the roof deck or on top of a drywall ceiling.

  (b) Loose-fill insulation. When loose-fill insulation is installed, the minimum installed weight per square foot shall conform with the insulation manufacturer’s installed design weight per square foot at the manufacturer’s labeled R -value.

  (c) Wall insulation. Opaque portions of above grade walls separating conditioned spaces from unconditioned spaces or ambient air shall meet the following requirements:

  1. 2 × 4 inch framing shall have an overall assembly U -factor not exceeding U-0.095 Exception to Section 150.0(c)1: Existing walls already insulated to a U -factor not exceeding U-0.110 or already insulated between framing members with insulation having an installed thermal resistance of R-11 or greater.
  2. 2 × 6 inch or greater framing shall have an overall assembly U -factor not exceeding U-0.069.
  3. Opaque nonframed assemblies shall have an overall assembly U -factor not exceeding U-0.102.
  4. Bay or bow window roofs and floors shall be insulated to meet the wall insulation requirements of Table 150.1-A.
  5. Masonry/mass walls shall be insulated to meet the wall insulation requirements of Table 150.1-A.
  6. In wood framed assemblies, compliance with U -factors may be demonstrated by installing wall insulation with an R -value of R-15 in 2x4 assemblies, and R-21 in 2x6 assemblies with 16 inches on center spacing.

  (d) Raised-floor insulation. Raised floors separating conditioned space from unconditioned space or ambient air shall have an overall assembly U -factor not exceeding U-0.037. In a wood framed assembly, compliance with the U -factor may be demonstrated by installing insulation with an R -value of 19 or greater.

  Exception to Section 150.0(d): A building with a controlled ventilation or unvented crawlspace may omit raised floor insulation if all of the following are met: i. The foundation walls are insulated to meet the wall insulation minimums as shown in Table 150.1-A; and

  ii. A Class I or Class II vapor retarder is placed over the entire floor of the crawl space; and iii. Vents between the crawlspace and outside air are fitted with automatically operated louvers that are temperature actuated; and

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  SINGLE-FAMILY RESIDENTIAL BUILDINGS— MANDATORY FEATURES AND DEVICES

  iv. The requirements in Reference Residential Appendix RA4.5.1.

  (e) Installation of fireplaces, decorative gas appliances and gas logs. If a masonry or factory-built fireplace is installed, it shall comply with Section 110.5, Section 4.503 of Part 11, and shall have the following:

  1. Closable metal or glass doors covering the entire opening of the firebox; and
• CRC § 453.4.7.5 Medium relevance — show source text

  453.4.7.5 Ventilation rates. Mechanical exhaust ventilation systems shall provide a minimum ventilation rate not less than 1 cubic feet per minute per square foot [0.00508 m [3] /(s·m [2] ) ] of floor area, or 6 air exchanges per hour, whichever is greater. Systems shall operate continuously at the designed ventilation rate.

  Exception: Refer to California Fire Code Section 5001.3 Performance-based design alternatives, as approved by the Fire Code Official.

  453.4.7.6 Reserved.

  453.4.7.7 Mechanical ventilation system balancing. Mechanical ventilation systems shall be designed and balanced such that during normal and emergency conditions the door opening forces comply with the requirements of Sections 1010.1.3 and Chapter 11B as applicable. Emergency conditions shall include: supply fan shutdown or failure, closing of smoke dampers or combination fire/smoke dampers, or emergency power.

  453.5 Fire protection systems. See Chapter 9.

  453.6 Means of egress.

  453.6.1 Access to exits. Every room of a laboratory suite containing hazardous materials and having a floor area of 500 square feet (19 m2) or more shall have access to not less than two separate exits or exit-access doorways in accordance with Section 1006.2.

  453.6.2 Door swing. All exit and exit-access doors serving areas with hazardous materials shall swing in the direction of exit travel, regardless of the occupant load served.

  453.6.3 Panic hardware. Exit and exit access doors from areas with hazardous materials shall not be provided with a latch or lock unless it is panic hardware or fire exit hardware.

  453.6.4 Buildings of four stories or more. A minimum of one exit shall be provided to serve the floor on each side of the 2-hour fire barrier and shall comply with the provisions of Chapter 10.

  453.6.5 Reserved.

  453.7 Hazardous materials.

  453.7.1 Multiple hazards. When a hazardous material has multiple hazards, all hazards shall be addressed and controlled in accor- dance with the provisions of this code and the California Fire Code.

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  SPECIAL DETAILED REQUIREMENTS BASED ON OCCUPANCY AND USE

  453.7.2 Percentage of maximum allowable quantities. The percentage of the maximum allowable quantity of hazardous materi- als per laboratory suite permitted for each story level within a building shall be in accordance with Table 453.7.2.1.

  TABLE 453.7.2.1—HAZARDOUS MATERIALS QUANTITY PER LABORATORY SUITE	Col2	Col3	Col4	Col5	Col6	Col7	Col8
  STORY	STORY	PERCENTAGE OF MAXIMUM ALLOWABLE QUANTITY PER **_LABORATORY SUITEa,

• CRC § 2.5 Medium relevance — show source text

  Parapet construction R302.2.5 Scope R101.2 Separation R302.2 Structural independence R302.2.6 Trusses

  Steel R505.1.3, R804.3.6 Wood R502.12, R802.10 Tubular Daylighting Device (TDD) (see Skylights) Two-Family Dwellings R302.3

  Under Floor

  Space R408

  Vapor Retarders R702.7 Capillary break R506.2.3.1 Under floor R408.8 Vehicular Gates Appendix BH Veneer

  Masonry R703.7 Ventilation Adjoining rooms R325.1.3 Bathroom and kitchen R325.2

  Habitable rooms R325.1

  Roof R806

  Under floor R408.1 Venting (Mechanical) Chimney and vent connectors R1006 Fireplace R1006 General R325.3

  Violations R113 Visible Transmittance (VT)

  Wall Furnace (see Appliance) Wallboard (see Gypsum) Walls

  Bathtub compartments R327.2 Bracing, steel R603.9 Bracing, wood R602.10 Construction Chapter 6 Covering Chapter 7 Crawl space R202 Cripple R602.9

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  INDEX

  Deflection R301.7

  Exterior, defined R202 Exterior covering R703 Finishes R327.2, R702 Fireplace R1001.5 Foundation R404 Insulating concrete form R608.3, R608.4, R608.5.3 Steel framing R603 Structural insulated panels (SIP) R610 Thickness, masonry chimneys R1003.10 Wood framing R602 Waste

  Construction waste R334

  Water Closet R326.1, R327 Clearances for R327.1 Waterproofing And dampproofing R406 Wells (see Individual Water Supply) Whirlpool Bathtubs R324.3.1, P2720 Wind

  Design criteria R301.2, R301.2.1 Speed maps Figure R301.2(2) Window R609 Emergency Escape and Rescue Openings R319, R321.2.2 Fall protection R321.2 Glazing R324 Light and ventilation R325 Opening limiting devices R321.2.2 Wood

  Floor construction R502

  Foundation walls R404.2 Protection against decay R304 Roof-ceiling construction R802 Shakes R905.8 Shingles R905.7 Trusses R502.12, R802.10 Walls R602

  Yard R318.1, R319.1, R319.2.4, R325.1.1

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  HISTORY NOTE APPENDIX

• CRC § 2.3 Medium relevance — show source text

  SIP R610.8

  Steel R603.6

  Wood R602.7

  Hearth R1001.9

  Extension R1001.10, R1001.9

  Heaters

  Masonry R1002 Heating Required R325.8 Height Ceiling R313 Mezzanines R314.2 Sleeping lofts R315.3 Hollow-Unit Masonry (see Masonry)

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  INDEX

  Roof shingles R905.4 Methods Water distribution pipe sizing Appendix CF Mezzanines (see also Sleeping Lofts) R314, R321 Modifications R104.2.3 Moisture Content, Building Materials R109.1.4.1

  Moisture Control R702.7

  Mortar

  Joints R606.3.1 Multiple Flues R1003.13

  Natural Light (see Light) Natural Ventilation (see Ventilation) Notching Steel joists R505.2.5, R505.3.5, R804.2.5, R804.3.3 Steel studs R603.2.6, R603.3.4 Wood joists R502.8, R802.7.1 Wood studs R602.6 Wood top plates R602.6.1

  Opening Protection R302.5

  Parapets R302.2.2, R606.4.4 Particleboard

  Floor R503.3

  Walls R605 Patio Covers Appendix BF Penetrations R302.4, R302.5 Permits 1.8.4, R105, R105.5.1 Permit fees Appendix AB Photovoltaic Panel Systems R907 Ground-mounted definition R202

  Photovoltaic Support Structure, Elevated R202, R324.8, R324.8.1, R324.8.2 Piers R606.7

  Masonry R404.1.9 Planning Building Chapter 3 Plans R106

  Plaster

  Exterior R703.7

  Interior R702.2

  Platform Lifts R323.2, R323.3 Plumbing Fixture clearances R327

  Fixtures R326, R327 Inspection 109.1.2 Requirements and definitions R202 System, definition R202 Plywood Application R703.5 Materials, walls R604

  Precast Concrete

  Footings R403.4 Foundation material R402.3.1

  Foundation walls R404.5

  Protection Against decay and termites R304, R305 Against radon Appendix BE Public Way R318.1, R319.1 Purlins R802.4.5

  Hot Tubs (see Swimming Pools) R324.3.1, R328 Hurricane (see Storm Shelter)

  Impact Protective System Energy storage system R330.8 Flood R306.1.4.2, R306.3.3 Human impact R324.3 Storm shelter R307.2.1

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

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  FOUNDATIONS

  FIGURE R403.1(1)—PLAIN CONCRETE FOOTINGS WITH MASONRY AND CONCRETE STEM WALLS IN SEISMIC DESIGN CATEGORIES A, B AND C [a, b, c, d, e, f]

  For SI: 1 inch = 25.4 mm. W = Width of footing, T = Thickness of footing and P = Projection per Section R403.1.1.

  NOTES:

  a. See Section R404.3 for sill requirements. b. See Section R403.1.6 for sill attachment.

  c. See Section R506.3.3 for vapor barrier requirements. d. See Section R403.1 for base.

  e. See Figure R403.1.3 for additional footing requirements for structures in Seismic Design Categories D 0, D 1 and D 2 and townhouses in Seismic Design Category C. f. See Section R408 for under-floor ventilation and access requirements.

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  FOUNDATIONS

  FIGURE R403.1(2)—PERMANENT WOOD FOUNDATION BASEMENT WALL SECTION

  PRESSURE-PRESERVATIVE TREATED

  FLASHING

  FIELD-APPLIED 2 � 6 IN. TOP PLATE

  2 � 6 IN. TOP PLATE

  MIN. 3.5-IN. CONCRETE SLAB WITH s

  VAPOR BARRIER AND OPTIONAL

  1-IN. SCREED BOARD

  2 � 6 IN. STUD INSULATED

  AS APPROPRIATE AND WARM SIDE

  VAPOR BARRIER

  FINISH GRADE SLOPE [1] / 2 IN. PER FOOT, MIN. 6 FT. FROM WALL

  PRESSURE-PRESERVATIVETREATED PLYWOOD (SEE TABLE R404.2.3)

  6 MIL POLYETHYLENE FILM

  6 MIL POLYETHYLENE FILM ON CRUSHED STONE OR GRAVEL BACKFILL

  PRESSURE-PRESERVATIVE TREATED 2 � 6 IN. BOTTOM

  Col1	2-IN. AIR GAP
  . BACKFILL)	2-IN. AIR GAP 4 IN. 1-IN.-THICK PRESSURE TREATED LUMBER OR PROTECTING TOP OF P PRESS TREAT PLATE PRES TREA PLATE .
  HED 4 IN. 16 IN	HED 4 IN. 16 IN

  STONE FILL UNDER FLOOR (SEE SECTION R403.2)

  6 IN.

  For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 mil = 0.0254 mm.

  FIGURE R403.1(3)—PERMANENT WOOD FOUNDATION CRAWL SPACE SECTION

  PRESSURE-PRESERVATIVE TREATED

  6 MIL POLYETHYLENE FILM

  6 IN.

  6 IN. GRAVEL OR CRUSHED STONE (SEE SECTION R403.2)

  For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 mil = 0.0254 mm.

• CRC § 8.4 Medium relevance — show source text

  Floor R503.3

  Walls R605 Patio Covers Appendix BF Penetrations R302.4, R302.5 Permits 1.8.4, R105, R105.5.1 Permit fees Appendix AB Photovoltaic Panel Systems R907 Ground-mounted definition R202

  Photovoltaic Support Structure, Elevated R202, R324.8, R324.8.1, R324.8.2 Piers R606.7

  Masonry R404.1.9 Planning Building Chapter 3 Plans R106

  Plaster

  Exterior R703.7

  Interior R702.2

  Platform Lifts R323.2, R323.3 Plumbing Fixture clearances R327

  Fixtures R326, R327 Inspection 109.1.2 Requirements and definitions R202 System, definition R202 Plywood Application R703.5 Materials, walls R604

  Precast Concrete

  Footings R403.4 Foundation material R402.3.1

  Foundation walls R404.5

  Protection Against decay and termites R304, R305 Against radon Appendix BE Public Way R318.1, R319.1 Purlins R802.4.5

  Hot Tubs (see Swimming Pools) R324.3.1, R328 Hurricane (see Storm Shelter)

  Impact Protective System Energy storage system R330.8 Flood R306.1.4.2, R306.3.3 Human impact R324.3 Storm shelter R307.2.1

  Windborne debris R301.2.1.2 Indirectly Conditioned Space (see Conditioned Space) Inflatable Amusement Device

  Defined R202

  Inlet To masonry chimneys R1003.16 Inspection On-site 1.8.4, R109.1 Insulation

  Above-deck R906 Flame spread R302.10 Foam plastic R303 Interior

  Lath R702.2.3

  Other finishes R702.5

  Plaster R702.2 Wall covering Chapter 7 Intermodal Shipping Container R301.1.4

  Joist

  Bearing R502.6, R606.6.3.1

  Kitchen Height and area R312, R313 Sinks R326

  Ventilation R325.1.2

  Labeling Garage doors R609.4.1 Ladders

  Ships ladders R318.7.13 Sleeping lofts R315.5.3 Landings (see also Stairways, Ramps and Doors) R318.3, R318.3.1, R318.3.2, R318.7.6, R318.8.2, R321, R324.4.7, R325.6, R325.7 Lateral Support R502.7, R606.6.4, R607.5.2 Lath

  Exterior R703.7.1

  Interior R702.2.3

  Lavatories R326.1

  Clearances R327 Liability R104.8 Light R325 Lighting Adjoining rooms R325.1.3 Bathrooms R325.2

• CRC § 25.4 Medium relevance — show source text

  Where the building width perpendicular to the wall footing is greater than 32 feet, the footing width shall be increased by 2 inches and footing depth shall be increased by 1
  inch for every 4 feet of increase in building width.
  d. Where the building width perpendicular to the wall footing is less than 32 feet, a 2-inch decrease in footing width and 1-inch decrease in footing depth is permitted for every 4
  feet of decrease in building width provided that the minimum width is 12 inches and minimum depth is 6 inches.
  SLAB
  ON GRADE
  BASEMENT
  CRAWL
  SPACE|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 47.9 N/m2.
  a. Linear interpolation of footing width is permitted between the soil bearing pressures in the table. Extrapolation is not permitted.
  b. The table is based on the following conditions and loads: building width, 32 feet; wall height, 9 feet; basement wall height, 8 feet; dead loads, 15 psf roof and ceiling assembly,
  10 psf floor assembly, 12 psf wall assembly; live loads, roof and ground snow loads as listed, 40 psf first floor, 30 psf second and third floors. Footing sizes are calculated
  assuming a clear span roof/ceiling assembly and an interior bearing wall or beam at each floor.
  c. Where the building width perpendicular to the wall footing is greater than 32 feet, the footing width shall be increased by 2 inches and footing depth shall be increased by 1
  inch for every 4 feet of increase in building width.
  d. Where the building width perpendicular to the wall footing is less than 32 feet, a 2-inch decrease in footing width and 1-inch decrease in footing depth is permitted for every 4
  feet of decrease in building width provided that the minimum width is 12 inches and minimum depth is 6 inches.
  SLAB
  ON GRADE
  BASEMENT
  CRAWL
  SPACE|

  2025 CALIFORNIA RESIDENTIAL CODE 4-9

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

  FOUNDATIONS

  FIGURE R403.1(1)—PLAIN CONCRETE FOOTINGS WITH MASONRY AND CONCRETE STEM WALLS IN SEISMIC DESIGN CATEGORIES A, B AND C [a, b, c, d, e, f]

  For SI: 1 inch = 25.4 mm. W = Width of footing, T = Thickness of footing and P = Projection per Section R403.1.1.

  NOTES:

  a. See Section R404.3 for sill requirements. b. See Section R403.1.6 for sill attachment.

  c. See Section R506.3.3 for vapor barrier requirements. d. See Section R403.1 for base.

  e. See Figure R403.1.3 for additional footing requirements for structures in Seismic Design Categories D 0, D 1 and D 2 and townhouses in Seismic Design Category C. f. See Section R408 for under-floor ventilation and access requirements.

  4-10 2025 CALIFORNIA RESIDENTIAL CODE

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

  FOUNDATIONS

• CRC § 707.1 Medium relevance — show source text

  TABLE 707.1

  CLEANOUTS

  For SI units: 1 inch = 25 mm

  TABLE 707.2 CLEANOUT MATERIALS FOR DRAIN, WASTE, AND VENT

  1 [HCD 1 & HCD 2] ABS and PVC installations are limited to not more

  than two stories of areas of residential accommodation.

  172 2025 CALIFORNIA PLUMBING CODE

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

  SANITARY DRAINAGE

  Exceptions:

  (1) Cleanouts shall be permitted to be omitted on a horizontal drain line less than 5 feet (1524 mm) in length unless such line is serving sinks or urinals.

  (2) Cleanouts shall be permitted to be omitted on a horizontal drainage pipe installed on a slope of 72 degrees (1.26 rad) or less from the vertical angle (one-fifth bend).

  (3) Excepting the building drain, its horizontal branches, kitchen sinks, and urinals, a cleanout shall not be required on a pipe or piping that is above the floor level of the lowest floor of the building.

  (4) An approved type of two-way cleanout fitting, installed inside the building wall near the connection between the building drain and the building sewer or installed outside of a building at the lower end of a building drain and extended to grade, shall be permitted to be substituted for an upper terminal cleanout.

  707.4.1 Load Rated Cover. Cleanout floor covers and top rims meant to take loads shall be rated for the loading in accordance with ASME A112.36.2M. 707.5 Cleaning. Each cleanout shall be installed so that it opens to allow cleaning in the direction of flow of the soil or waste or at right angles thereto and, except in the case of wye branch and end-of-line cleanouts, shall be installed vertically above the flow line of the pipe.

  707.6 Extension. Each cleanout extension shall be considered as drainage piping and each 90 degree (1.57 rad) cleanout extension shall be extended from a wye-type fitting or other approved fitting of equivalent sweep.

  707.7 Interceptor. Each cleanout for an interceptor shall be outside of such interceptor.

  707.8 Access. Each cleanout, unless installed under an approved cover plate, shall be above grade, readily accessible, and so located as to serve the purpose for which it is intended. Cleanouts located under cover plates shall be so installed as to provide the clearances and accessibility required by this section.

  707.9 Clearance. Each cleanout in piping 2 inches (50 mm) or less in size shall be so installed that there is a clearance of not less than 18 inches (457 mm) by 18 inches (457 mm) in front of the cleanout. Cleanouts in piping exceeding 2 inches (50 mm) shall have a clearance of not less than 24 inches (610 mm) by 24 inches (610 mm) in front of the cleanout. Cleanouts in under-floor piping shall be extended to or above the finished floor or shall be extended outside the building where there is less than 18 inches (457 mm) vertical overall, allowing for obstructions such as ducts, beams, and piping, and 30 inches of (762 mm) horizontal clearance from the means of access to such cleanout.