Weatherproofing & Drainage

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

• CBC § 5.403 Medium relevance — show source text

  REFERENCE STUDY PERIOD.

  TEST.

  TYPE III ENVIRONMENTAL PRODUCT DECLARATION (EPD).

  FACTORY-SPECIFIC EPD.

  INDUSTRY-WIDE EPD (IW-EPD).

  PRODUCT-SPECIFIC EPD.

  SECTION 5.403—FOUNDATION SYSTEMS (RESERVED)

  SECTION 5.404—EFFICIENT FRAMING TECHNIQUES (RESERVED)

  SECTION 5.405—MATERIAL SOURCES (RESERVED)

  SECTION 5.406—ENHANCED DURABILITY AND REDUCED MAINTENANCE (RESERVED)

  SECTION 5.407—WATER RESISTANCE AND MOISTURE MANAGEMENT

  5.407.1 Weather protection. Provide a weather-resistant exterior wall and foundation envelope as required by California Building Code Section 1402.2 (Weather Protection), manufacturer’s installation instructions or local ordinance, whichever is more stringent.

  5.407.2 Moisture control. Employ moisture control measures by the following methods.

  5.407.2.1 Sprinklers. Design and maintain landscape irrigation systems to prevent spray on structures.

  5.407.2.2 Entries and openings. Design exterior entries and/or openings subject to foot traffic or wind-driven rain to prevent water intrusion into buildings as follows:

  5.407.2.2.1 Exterior door protection. Primary exterior entries shall be covered to prevent water intrusion by using nonabsorbent floor and wall finishes within at least 2 feet around and perpendicular to such openings plus at least one of the following:

  1. An installed awning at least 4 feet in depth.

  2. The door is protected by a roof overhang at least 4 feet in depth.

  3. The door is recessed at least 4 feet.

  4. Other methods which provide equivalent protection.

  5.407.2.2.2 Flashing. Install flashings integrated with a drainage plane.

  2025 CALIFORNIA GREEN BUILDING STANDARDS CODE 5-23

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

  NONRESIDENTIAL MANDATORY MEASURES

  SECTION 5.408—CONSTRUCTION WASTE REDUCTION, DISPOSAL AND RECYCLING

  5.408.1 Construction waste management. Recycle and/or salvage for reuse a minimum of 65 percent of the nonhazardous construction and demolition waste in accordance with Section 5.408.1.1, 5.408.1.2 or 5.408.1.3; or meet a local construction and demolition waste management ordinance, whichever is more stringent.

  5.408.1.1 Construction waste management plan. Where a local jurisdiction does not have a construction and demolition waste management ordinance that is more stringent, submit a construction waste management plan that:

  1. Identifies the construction and demolition waste materials to be diverted from disposal by efficient usage, recycling, reuse on the project or salvage for future use or sale.

  2. Determines if construction and demolition waste materials will be sorted on-site (source-separated) or bulk mixed (single stream).

  3. Identifies diversion facilities where construction and demolition waste material collected will be taken.

  4. Specifies that the amount of construction and demolition waste materials diverted shall be calculated by weight or volume, but not by both.

• CBC § 4-11 Medium relevance — show source text

  (Equation A4.4-11) Weight of material (percent) = [Weight of material (lbs) ÷ Weight of assembly (lbs)] × 100 (See Equation A4.4-7) RC M (percent) = Postconsumer content percentage + ( [1] / 2 ) Preconsumer content percentage

  Method 2: Recycled content (postconsumer and preconsumer) provided in pounds

  (Equation A4.4-12) PRC M (percent) = [RC M (lbs) ÷ Weight of material (lbs)] × 100 (Equation A4.4-13) RC M (lbs) = Postconsumer content (lbs) + ( [1] / 2 ) Preconsumer content (lbs)

  Note: If the manufacturer reports total recycled content of a material as one percentage in lieu of separately reporting preconsumer and postconsumer values, the total shall be considered preconsumer recycled material.

  A4.405.3.1.5 Alternate method for concrete. When Supplementary Cementitious Materials (SCMs), such as fly ash or ground blast furnace slag cement, are used in concrete, an alternate method of calculating and reporting recycled content in concrete products shall be permitted. When determining the recycled content value, the percent recycled content shall be multiplied by the cost of the cementitious materials only, not the total cost of the concrete.

  A4.405.4 Use of building materials from rapidly renewable sources. One or more of the following materials manufactured from rapidly renewable sources or agricultural by-products is used:

  1. Insulation.

  2. Bamboo or cork.

  3. Engineered products.

  4. Agricultural based products.

  5. Other products acceptable to the enforcing agency.

  Note: The intent of this section is to utilize building materials and products which are typically harvested within a 10-year or shorter cycle.

  SECTION A4.406—ENHANCED DURABILITY AND REDUCED MAINTENANCE (RESERVED)

  SECTION A4.407—WATER RESISTANCE AND MOISTURE MANAGEMENT

  A4.407.1 Drainage around foundations. Install foundation and landscape drains which discharge to a dry well, sump, bioswale or other approved on-site location.

  A4.407.2 Roof drainage. Install gutter and downspout systems to route water at least 5 feet away from the foundation or connect to landscape drains which discharge to a dry well, sump, bioswale, rainwater capture system or other approved on-site location.

  A4.407.3 Flashing details. Provide flashing details on the building plans which comply with accepted industry standards or manufacturer’s instructions. Details are shown on house plans at all of the following locations:

  1. Around windows and doors.

  2. Roof valleys.

  3. Deck connections to the structure.

  4. Roof-to-wall intersections.

  5. Chimneys to roof intersections.

  6. Drip caps above windows and doors with architectural projections.

  Note: Reference details may be found in the Residential Sheet Metal Guidelines published by the Sheet Metal and Air Conditioning Contractors’ National Association Inc.

  A4.407.4 Material protection. Protect building materials delivered to the construction site from rain and other sources of moisture.

  A4.407.5 Ice and water barriers. In Climate Zone 16, an ice and water barrier is installed at valley, eaves and wall to roof intersections. The ice and water barrier shall extend at least 24 inches inside the exterior wall line or as specified by the manufacturer’s installation instructions.

• CBC § 407.1 Medium relevance — show source text

  SECTION A4.406—ENHANCED DURABILITY AND REDUCED MAINTENANCE (RESERVED)

  SECTION A4.407—WATER RESISTANCE AND MOISTURE MANAGEMENT

  A4.407.1 Drainage around foundations. Install foundation and landscape drains which discharge to a dry well, sump, bioswale or other approved on-site location.

  A4.407.2 Roof drainage. Install gutter and downspout systems to route water at least 5 feet away from the foundation or connect to landscape drains which discharge to a dry well, sump, bioswale, rainwater capture system or other approved on-site location.

  A4.407.3 Flashing details. Provide flashing details on the building plans which comply with accepted industry standards or manufacturer’s instructions. Details are shown on house plans at all of the following locations:

  1. Around windows and doors.

  2. Roof valleys.

  3. Deck connections to the structure.

  4. Roof-to-wall intersections.

  5. Chimneys to roof intersections.

  6. Drip caps above windows and doors with architectural projections.

  Note: Reference details may be found in the Residential Sheet Metal Guidelines published by the Sheet Metal and Air Conditioning Contractors’ National Association Inc.

  A4.407.4 Material protection. Protect building materials delivered to the construction site from rain and other sources of moisture.

  A4.407.5 Ice and water barriers. In Climate Zone 16, an ice and water barrier is installed at valley, eaves and wall to roof intersections. The ice and water barrier shall extend at least 24 inches inside the exterior wall line or as specified by the manufacturer’s installation instructions.

  2025 CALIFORNIA GREEN BUILDING STANDARDS CODE APPENDIX A4-17

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

  APPENDIX A4 — RESIDENTIAL VOLUNTARY MEASURES

  A4.407.6 Door protection. Exterior doors to the dwelling are covered to prevent water intrusion by one or more of the following:

  1. An awning at least 4 feet in depth is installed.

  2. The door is protected by a roof overhang at least 4 feet in depth.

  3. The door is recessed at least 4 feet.

  4. Other methods which provide equivalent protection.

  A4.407.7 Roof overhangs. A permanent overhang or awning at least 2 feet in depth is provided at all exterior walls.

  SECTION A4.408—CONSTRUCTION WASTE REDUCTION, DISPOSAL AND RECYCLING

  A4.408.1 Enhanced construction waste reduction. Nonhazardous construction and demolition debris generated at the site is diverted to recycle or salvage in compliance with one of the following:

  Tier 1. At least a 65 percent reduction. Any mixed recyclables that are sent to mixed-waste recycling facilities shall include a qualified third party verified facility average diversion rate. Verification of diversion rates shall meet minimum certification eligibility guidelines, acceptable to the local enforcing agency.

  Tier 2. At least a 75 percent reduction with a third-party verification as required for Tier 1.

  Exceptions:

  1. Equivalent or alternative waste reduction methods are developed by working with local agencies if diversion or recycle facilities capable of compliance with this item do not exist.
  2. The enforcing agency may make exceptions to the requirements of this section when jobsites are located in areas beyond the haul boundaries of the diversion facility.
• CBC § 7.3 Medium relevance — show source text

  ** In Dry (B) climate zones indicated in Section R702.7.3 and Table R702.7.3, water-resistive barriers shall comply with one of the following:

  1. The water-resistive barrier shall be two layers of 10-minute Grade D paper or have a water resistance equal to or greater than two layers of a water-resistive barrier complying with ASTM E2556, Type I. The individual layers shall be installed independently such that each layer provides a separate continuous plane. Flashing installed in accordance with Section R703.4 and intended to drain to the water-resistive barrier shall be directed between the layers.
  2. The water-resistive barrier shall be 60-minute Grade D paper or have a water resistance equal to or greater than one layer of a water-resistive barrier complying with ASTM E2556, Type II. The water-resistive barrier shall be separated from the stucco by a layer of foam plastic insulating sheathing, other non-water-absorbing layer, a drainage space or means of drainage complying with Section R703.7.3.2. Flashing installed in accordance with Section 703.4 and intended to drain to the water-resistive barrier shall be directed to the exterior side of the water-resistive barrier.

  R703.7.3.2 Moist or marine climates. In the Moist (A) or Marine (C) climate zones indicated in Section R702.7.3 and Table R702.7.3, water-resistive barriers shall comply with one of the following:

  1. In addition to complying with Section R703.7.3.1, a space or drainage material not less than [3] / 16 inch (5 mm) in depth shall be added to the exterior side of the water-resistive barrier.

  2. In addition to complying with Section R703.7.3.1, Item 2, drainage on the exterior of the water-resistive barrier shall have a drainage efficiency of not less than 90 percent, as measured in accordance with ASTM E2273 or Annex A2 of ASTM E2925.

  R703.7.4 Application. Each coat shall be kept in a moist condition for at least 48 hours prior to application of the next coat.

  Exception: Applications installed in accordance with ASTM C926.

  R703.7.5 Curing. The finish coat for two-coat cement plaster shall not be applied sooner than seven days after application of the first coat. For three-coat cement plaster, the second coat shall not be applied sooner than 48 hours after application of the first coat. The finish coat for three-coat cement plaster shall not be applied sooner than seven days after application of the second coat.

  R703.8 Anchored stone and masonry veneer, general. Anchored stone and masonry veneer shall be installed in accordance with this chapter, Table R703.3(1) and Figures R703.8(1) and R703.8(2). These veneers installed over a backing of wood or cold-formed steel shall be limited to the first story above grade plane and shall not exceed 5 inches (127 mm) in thickness. See Section R602.10 for wall bracing requirements for masonry veneer for wood-framed construction and Section R603.9.5 for wall bracing requirements for masonry veneer for cold-formed steel construction.

• CBC § 209.1 Medium relevance — show source text

  2. Certifies that automatic daylighting controls meet the applicable requirements of Sections A6.209.1 and A6.209.2.3.2.4.
  3. Certifies that when a multilevel astronomical time switch is used to meet Exception 3 to Section A6.209.2.3.2.2 all general lighting in the skylit area is controlled by a multilevel astronomical time switch that meets the applicable requirements of Section A6.209.1 and that has an override switch that meets the requirements of Section A209.2.4.2.
  4. Certifies that lighting controls meet the requirements of Sections A6.209.2.1 through A6.209.2.3 and Title 24, Part 6, Sections 131(e) and (f) and 146(a)2, as applicable.
  5. Certifies that automatic lighting controls meet the applicable requirements of Sections A6.209.1 and A6.209.2.4.
  6. Certifies that occupant-sensors meet the applicable requirements of Sections A6.209.1 and A6.209.2.4.
  7. Certified that outdoor lighting controls meet the applicable requirements of Sections A6.209.1 and A6.209.3.

  SECTION A6.210 [OSHPD 1, 2 & 4]—APPLIANCES

  A6.210.1 Appliances regulated by the Appliance Efficiency Regulations. Any appliance for which there is a California standard established in the Appliance Efficiency Regulations may be installed only if the manufacturer has certified to the Commission, as specified in those regulations, that the appliance complies with the applicable standard for that appliance.

  Note: For certified appliances, go to www.energy.ca.gov/appliances/database/.

  DIVISION A6.4 – MATERIAL CONSERVATION AND RESOURCE EFFICIENCY

  SECTION A6.401—GENERAL

  A6.401.1 Scope. The provisions of this chapter shall outline means of achieving material conservation and resource efficiency through reuse of existing building stock and materials; use of recycled, regional, rapidly renewable and certified wood materials; and employment of techniques to reduce pollution through recycling of materials.

  SECTION A6.407 [OSHPD 1, 2 & 4]—WATER RESISTANCE AND MOISTURE MANAGEMENT

  A6.407.3 Weather protection. Provide a weather-resistant exterior wall and foundation envelope as required by California Building Code Section 1403.2 and California Energy Code Section 150, manufacturer’s installation instructions or local ordinance, whichever is more stringent.

  A6.407.4 Moisture control. Employ moisture control measures by the following methods.

  A6.407.4.1 Sprinklers. Design and maintain landscape irrigation systems to prevent spray on structures.

  A6.407.4.2 Entries and openings. Design exterior entries and/or openings subject to foot traffic or wind-driven rain to prevent water intrusion into buildings.

  Notes:

  1. Use features such as overhangs and recesses and flashings integrated with a drainage plane.

  APPENDIX A6.1-32 2025 CALIFORNIA GREEN BUILDING STANDARDS CODE

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

  APPENDIX A6.1 — VOLUNTARY STANDARDS FOR HEALTH FACILITIES [OSHPD 1, 2 & 4]

• CBC § 5.2 Medium relevance — show source text

  Rainfall intensity shall be determined in inches per hour for 15-minute duration storms for the risk categories given in Table 1611 A .1. The ponding head shall be based on structural analysis as the depth of water due to deflections of the roof subjected to unfactored rain load and unfactored dead load.

  Equation 16 A -20 R = 5.2( d s + d h + d p ) For SI: R = 0.0098( d s + d h + d p )

  where:

  d h = Hydraulic head equal to the depth of water on the undeflected roof above the inlet of the secondary drainage system for structural loading (SDSL) required to achieve the design flow, in inches (mm). d p = Ponding head equal to the depth of water due to deflections of the roof subjected to unfactored rain load and unfactored dead load, in inches (mm).

  d s = Static head equal to the depth of water on the undeflected roof up to the inlet of the secondary drainage system for structural loading (SDSL), in inches (mm). R = Rain load, in pounds per square foot (kN/m [2] ).

  16A-32 2025 CALIFORNIA BUILDING CODE

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

  STRUCTURAL DESIGN

  SDSL is the roof drainage system through which water is drained from the roof when the drainage systems listed in ASCE 7 Section 8.2 (a) through (d) are blocked or not working.

  TABLE 1611A.1—DESIGN STORM RETURN PERIOD BY RISK CATEGORY	Col2
  RISK CATEGORY	DESIGN STORM RETURN PERIOD
  I & II	100 years
  III	200 years
  IV	500 years

  1611 A .2 Ponding instability. Ponding instability on roofs shall be evaluated in accordance with ASCE 7.

  1611 A .3 Controlled drainage. Roofs equipped with hardware to control the rate of drainage shall be equipped with a secondary drainage system at a higher elevation that limits accumulation of water on the roof above that elevation. Such roofs shall be designed to sustain the load of rainwater that will accumulate on them to the elevation of the secondary drainage system plus the uniform load caused by water that rises above the inlet of the secondary drainage system at its design flow determined from Section 1611 A .1. Such roofs shall be checked for ponding instability in accordance with Section 1611 A .2.

  SECTION 1612 A —FLOOD LOADS

  1612 A .1 General. Within flood hazard areas as established in Section 1612 A .3, all new construction of buildings, structures and portions of buildings and structures, including substantial improvement and restoration of substantial damage to buildings and structures, shall be designed and constructed to resist the effects of flood hazards and flood loads. For buildings that are located in more than one flood hazard area, the provisions associated with the most restrictive flood hazard area shall apply.

• CBC § 9.1.5. Medium relevance — show source text

  R703.4 Flashing. Approved corrosion-resistant flashing shall be applied in a manner to prevent entry of water into the wall cavity or penetration of water to the building structural framing components. Overlapped flashing shall be applied in shingle fashion. Selfadhered membranes used as flashing shall comply with AAMA 711. Fluid-applied membranes used as flashing in exterior walls shall comply with AAMA 714. The flashing shall extend to the surface of the exterior wall finish. Flashing shall be installed above deck ledgers in accordance with Section R507.9.1.5.

  Approved corrosion-resistant flashings shall be installed at the following locations:

  1. Exterior window and door openings. Flashing at exterior window and door openings shall be installed in accordance with Section R703.4.1.

  2. At the intersection of chimneys or other masonry construction with frame or stucco walls, with projecting lips on both sides under stucco copings.

  3. Under and at the ends of masonry, wood or metal copings and sills.

  4. Continuously above all projecting wood trim.

  5. Where exterior porches, decks or stairs attach to a wall or floor assembly of wood-frame construction.

  6. At wall and roof intersections.

  7. At built-in gutters.

  R703.4.1 Flashing installation at exterior window and door openings. Flashing at exterior window and door openings shall extend to the surface of the exterior wall finish or to a water-resistive barrier complying with Section R703.2 for subsequent drainage. Air sealing shall be installed around all window and door openings on the interior side of the rough opening gap. Mechanically attached flexible flashings shall comply with AAMA 712. Flashing at exterior window and door openings shall be installed in accordance with one or more of the following:

  1. The fenestration manufacturer’s installation and flashing instructions, or for applications not addressed in the fenestration manufacturer’s instructions, in accordance with the flashing or water-resistive barrier manufacturer’s instructions. Where flashing instructions or details are not provided, pan flashing shall be installed at the sill of exterior window and

  2025 CALIFORNIA RESIDENTIAL CODE 7-13

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

  WALL COVERING

  door openings. Pan flashing shall be sealed or sloped in such a manner as to direct water to the surface of the exterior wall finish or to the water-resistive barrier for subsequent drainage. Openings using pan flashing shall incorporate flashing or protection at the head and sides. 2. In accordance with the flashing design or method of a registered design professional. 3. In accordance with other approved methods.

  R703.5 Wood, hardboard and wood structural panel siding. Wood, hardboard and wood structural panel siding shall be installed in accordance with this section and Table R703.3(1). Hardboard siding shall comply with ANSI A135.5.

  R703.5.1 Vertical wood siding. Wood siding applied vertically shall be nailed to horizontal nailing strips or blocking set not more than 24 inches (610 mm) on center.

• CBC § 1404.3.1 Medium relevance — show source text

  �

  EXTERIOR WALLS

  1404.3.1 Spray foam plastic insulation for moisture control with Class II and III vapor retarders. For purposes of compliance with Tables 1404.3(3) and 1404.3(4), spray foam with a maximum permeance of 1.5 perms at the installed thickness applied to the interior side of wood structural panels, fiberboard, insulating sheathing or gypsum shall be deemed to meet the continuous insulation moisture control requirement in accordance with one of the following conditions:

  1. The spray foam R -value meets or exceeds the specified continuous insulation R-value.
  2. The combined R -value of the spray foam and continuous insulation is equal to or greater than the specified continuous insulation R -value.

  1404.3.2 Vapor retarder installation. Vapor retarders shall be installed in accordance with the manufacturer’s instructions or an approved design. Where a vapor retarder also functions as a component of a continuous air barrier, the vapor retarder shall be installed as an air barrier in accordance with the California Energy Code . 1404.3.3 California Energy Code and International Energy Conservation Code Climate Zones. 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 Chapter 12, Table 1202.3.1. 1404.4 Flashing. Flashing shall be installed in such a manner so as to prevent moisture from entering the exterior wall or to redirect that moisture to the surface of the exterior wall covering or to a water-resistive barrier complying with Section 1403.2 and that is part of a means of drainage complying with Section 1402.2. Flashing shall be installed at the perimeters of exterior door and window assemblies in accordance with Section 1404.4.1, penetrations and terminations of exterior wall assemblies, exterior wall intersections with roofs, chimneys, porches, decks, balconies and similar projections and at built-in gutters and similar locations where moisture could enter the wall. Flashing with projecting flanges shall be installed on both sides and the ends of copings, under sills and continuously above projecting trim. Where self-adhered membranes are used as flashings of fenestration in exterior wall assemblies, those self-adhered flashings shall comply with AAMA 711. Where fluid applied membranes are used as flashing for exterior wall openings, those fluid applied membrane flashings shall comply with AAMA 714. 1404.4.1 Fenestration flashing. Flashing of the fenestration to the wall assembly shall comply with the fenestration manufacturer’s instructions or, for conditions not addressed by the fenestration manufacturer’s instructions, shall comply with one of the following:

  1. The water-resistive barrier manufacturer’s flashing instructions.
  2. The flashing manufacturer’s flashing instructions.
  3. A flashing design or method of a registered design professional.
  4. Other approved methods. 1404.4.2 Exterior wall pockets. In exterior walls of buildings or structures, wall pockets or crevices in which moisture can accumulate shall be avoided or protected with caps or drips, or other approved means shall be provided to prevent water damage.
• CBC § 2510.4 Medium relevance — show source text

  2510.4 Corrosion resistance. Metal lath and lath attachments shall be of corrosion-resistant material.

  2510.5 Backing. Backing or a lath shall provide sufficient rigidity to permit plaster applications.

  2025 CALIFORNIA BUILDING CODE 25-7

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

  GYPSUM PANEL PRODUCTS AND PLASTER

  2510.5.1 Support of lath. Where lath on vertical surfaces extends between rafters or other similar projecting members, solid backing shall be installed to provide support for lath and attachments.

  2510.5.2 Use of gypsum backing board. Gypsum backing for cement plaster shall be in accordance with Section 2510.5.2.1 or 2510.5.2.2.

  2510.5.2.1 Gypsum board as a backing board. Gypsum lath or gypsum wallboard shall not be used as a backing for cement plaster.

  Exception: Gypsum lath or gypsum wallboard is permitted, with a water-resistive barrier, as a backing for self-furred metal lath or self-furred wire fabric lath and cement plaster where either of the following conditions occur:

  1. On horizontal supports of ceilings or roof soffits.

  2. On interior walls.

  2510.5.2.2 Gypsum sheathing backing. Gypsum sheathing is permitted as a backing for metal or wire fabric lath and cement plaster on walls. A water-resistive barrier shall be provided in accordance with Section 2510.6.

  2510.5.3 Backing not required. Wire backing is not required under expanded metal lath or paperbacked wire fabric lath.

  [BF] 2510.6 Water-resistive barriers. Water-resistive barriers shall be installed as required in Section 1403.2 and shall comply with Section 2510.6.1 or 2510.6.2.

  Exception: Sections 2510.6.1 and 2510.6.2 shall not apply to construction where accumulation, condensation or freezing of moisture will not damage the materials.

  [BF] 2510.6.1 Dry climates. One of the following shall apply for dry (B) climate zones:

  1. The water-resistive barrier shall be two layers of 10-minute Grade D paper or have a water resistance equal to or greater than two layers of water-resistive barrier complying with ASTM E2556, Type I. The individual layers shall be installed independently such that each layer provides a separate continuous plane and any flashing, installed in accordance with Section 1404.4 and intended to drain to the water-resistive barrier, is directed between the layers.
  2. The water-resistive barrier shall be 60-minute Grade D paper or have a water resistance equal to or greater than one layer of water-resistive barrier complying with ASTM E2556, Type II. The water-resistive barrier shall be separated from the stucco by a layer of foam plastic insulating sheathing or other nonwater absorbing layer, or a drainage space or means of drainage complying with Section 2510.6.2. Flashing installed in accordance with Section 1404.4 and intended to drain to the water-resistive barrier shall be directed to the exterior side of the water-resistive barrier.
• CBC § 7.2.1 Medium relevance — show source text

  On wood-frame construction with an on-grade floor slab system, exterior plaster shall be applied to cover, but not extend below, lath, paper and screed.

  The proportion of aggregate to cementitious materials shall be as set forth in Table R702.1(3).

  R703.7.2.1 Weep screeds. A minimum 0.019-inch (0.5 mm) (No. 26 galvanized sheet gage), corrosion-resistant weep screed or plastic weep screed, with a minimum vertical attachment flange of 3 [1] / 2 inches (89 mm), shall be provided at or below the foundation plate line on exterior stud walls in accordance with ASTM C926. The weep screed shall be placed not less than 4 inches (102 mm) above the earth or 2 inches (51 mm) above paved areas and shall be of a type that will allow trapped water to drain to the exterior of the building. The weather-resistant barrier shall lap the attachment flange. The exterior lath shall cover and terminate on the attachment flange of the weep screed.

  R703.7.3 Water-resistive barriers. Water-resistive barriers shall be installed as required in Section R703.2 and shall comply with Section R703.7.3.1 or R703.7.3.2.

  Exception: Sections R703.7.3.1 and R703.7.3.2 shall not apply to construction where accumulation, condensation or freezing of moisture will not damage the materials.

  R703.7.3.1 Dry climates. In Dry (B) climate zones indicated in Section R702.7.3 and Table R702.7.3, water-resistive barriers shall comply with one of the following:

  1. The water-resistive barrier shall be two layers of 10-minute Grade D paper or have a water resistance equal to or greater than two layers of a water-resistive barrier complying with ASTM E2556, Type I. The individual layers shall be installed independently such that each layer provides a separate continuous plane. Flashing installed in accordance with Section R703.4 and intended to drain to the water-resistive barrier shall be directed between the layers.
  2. The water-resistive barrier shall be 60-minute Grade D paper or have a water resistance equal to or greater than one layer of a water-resistive barrier complying with ASTM E2556, Type II. The water-resistive barrier shall be separated from the stucco by a layer of foam plastic insulating sheathing, other non-water-absorbing layer, a drainage space or means of drainage complying with Section R703.7.3.2. Flashing installed in accordance with Section 703.4 and intended to drain to the water-resistive barrier shall be directed to the exterior side of the water-resistive barrier.

  R703.7.3.2 Moist or marine climates. In the Moist (A) or Marine (C) climate zones indicated in Section R702.7.3 and Table R702.7.3, water-resistive barriers shall comply with one of the following:

  1. In addition to complying with Section R703.7.3.1, a space or drainage material not less than [3] / 16 inch (5 mm) in depth shall be added to the exterior side of the water-resistive barrier.
• CBC § 5.407.1 Medium relevance — show source text

  4**
  Material
  Conservation
  and Resource
  Efficiency
  (continued)|Mandatory|Weather protection|5.407.1||||| |DIVISION 5.4
  Material
  Conservation
  and Resource
  Efficiency
  (continued)|DIVISION 5.4
  Material
  Conservation
  and Resource
  Efficiency
  (continued)|Mandatory|Moisture control: sprinklers|5.407.2.1||||| |DIVISION 5.4
  Material
  Conservation
  and Resource
  Efficiency
  (continued)|DIVISION 5.4
  Material
  Conservation
  and Resource
  Efficiency
  (continued)|Mandatory|Moisture control: exterior door protection|5.407.2.2.1||||| |DIVISION 5.4
  Material
  Conservation
  and Resource
  Efficiency
  (continued)|DIVISION 5.4
  Material
  Conservation
  and Resource
  Efficiency
  (continued)|Mandatory|Moisture control: flashing|5.407.2.2.2||||| |DIVISION 5.4
  Material
  Conservation
  and Resource
  Efficiency
  (continued)|DIVISION 5.4
  Material
  Conservation
  and Resource
  Efficiency
  (continued)|Mandatory|Construction waste management—comply with either:
  Sections 5.408.1.1, 5.408.1.2, 5.408.1.3 or more stringent local
  ordinance|5.408.1.1,
  5.408.1.2,
  5.408.1.3|||||

  APPENDIX A5-50 2025 CALIFORNIA GREEN BUILDING STANDARDS CODE

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

  APPENDIX A5 — NONRESIDENTIAL VOLUNTARY MEASURES

  CHAPTER 5 DIVISIONS	Col2	Col3	SECTION TITLE	CODE SECTION	Y	N	O	PLAN SHEET, SPEC OR ATTACH
  (continued) DIVISION 5.4 Material Conservation and Resource Efficiency Select One Elective	(continued) DIVISION 5.4 Material Conservation and Resource Efficiency Select One Elective	Mandatory	Construction waste management: documentation	5.408.1.4
  (continued) **DIVISION 5.

• CBC § 304.3.1 Medium relevance — show source text

  be sized based on the total accumulated connected load at each story or branch interval.

  C 304.3.1 Horizontal Stack Offsets. Horizontal

  stack offsets shall be sized in accordance with Table C 304.2 as required for building drains.

  C 304.3.2 Vertical Stack Offsets. Vertical stack off sets shall be sized in accordance with Table C 304.3 as required for stacks.

  C 304.4 Horizontal Stack Offset and Horizontal Branch

  Connections. Horizontal branch connections shall not connect to a horizontal stack offset or within 2 feet (610 mm) above or below the offset where such horizontal offset is located more than four branch intervals below the top of the stack.

  C 401.0 Vent System Sizing. C 401.1 Size of Vents. The size of vent piping shall be determined from the developed length and the total number of drainage fixture units connected in accordance with Table C 401.1. Vents shall be not less than one-half the required size of the drainage pipe size served as determined by Table C 304.3 for horizontal fixture branches and stacks nor less than 1 [1] ⁄ 4 inches

  (32 mm) in diameter. The drainage system shall be vented by not less than one vent pipe which shall be not less than one-half the size of the required building drain and which shall extend from the building drain or extension of building drain to the outdoors. Vents shall be installed in accordance with Chapter 9. C 401.2 Vent Stack. A vent stack shall be required for a drainage stack that extends five or more branch intervals above the building drain or horizontal branch. The developed length of the vent stack shall be measured from the lowest connection of a branch vent to the termination outdoors.

  C 401.3 Branch Vents. Where branch vents exceed 40 feet (12 192 mm) in developed length, such vent shall be increased by one pipe size for the entire developed length of the vent pipe. C 401.4 Venting Horizontal Offsets. Drainage stacks with horizontal offsets shall be vented where five or more branch intervals are located above the offset. The upper and lower section of the horizontal offset shall be vented in accordance

  with Section C 401.4.1 and Section C 401.4.2.

  C 401.4.1 Venting Upper Section. The vent for the upper section of the stack shall be vented as a separate stack with a vent stack connection installed at the base of the drainage stack. Such vent stack shall connect below the lowest horizontal branch or building drain. Where vent stack connects to the building drain, the connection shall be located downstream of the drainage stack and within a distance of 10 times the diameter of the drainage stack. C 401.4.2 Venting Lower Section. The vent for the lower section of the stack shall be vented by a yoke vent connecting between the offset and the next lower horizontal branch using a wye-branch fitting. The size of the yoke vent and connection shall be not less in diameter

  388 2025 CALIFORNIA PLUMBING CODE

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

  APPENDIX C

  TABLE C 303.3 DRAINAGE FIXTURE UNIT VALUES (DFU) FOR BATHROOM GROUPS [1, 2]