CALGreen · California Green Building Standards Code (CALGreen)

Stormwater pollution prevention for projects that disturb less than 1 acre

If your project disturbs under one acre and is not part of a larger development, CALGreen § 5.106.1 requires you to prevent stormwater pollution either by following a local stormwater/erosion ordinance or by using appropriate BMPs (soil-loss controls and good-housekeeping measures). If the site is part of a larger plan or disturbs one acre or more, § 5.106.2 applies and you must comply with applicable stormwater discharge/NPDES requirements.

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Last reviewed: July 6, 2026

What the code requires — 2-4 sentences

For any newly constructed project or addition that disturbs less than one acre of land and is not part of a larger common plan of development or sale, the project must prevent pollution of stormwater runoff during construction by either complying with a lawfully enacted local stormwater/erosion ordinance or by implementing effective best management practices (BMPs) (see § 5.106.1). If the work is part of a larger common plan or disturbs one acre or more, the project must comply with applicable stormwater discharge regulations and NPDES permit requirements under § 5.106.2.

The single most important rule: if your site disturbs < 1 acre and is not part of a larger plan, you cannot ignore stormwater controls — either follow the local ordinance or implement BMPs listed in § 5.106.1.

Requirements in detail

Applicability — who this covers

  • Applies to: newly constructed projects and additions that disturb less than one acre and are not part of a larger common plan of development or sale (see § 5.106.1).
  • If the project is part of a larger common plan (even if each parcel is < 1 acre), it is treated as a larger disturbance and falls under § 5.106.2, which requires compliance with lawfully enacted stormwater discharge regulations (including NPDES where applicable).

Two compliance paths (choose one or both)

  • Comply with a lawfully enacted local stormwater management and/or erosion control ordinance (§ 5.106.1.1).
  • Implement one or more effective BMPs to prevent soil loss and manage construction-related non-stormwater discharges (§ 5.106.1.2).

What BMPs look like (two categories in the code)

  • Soil loss BMPs (examples, not exclusive): scheduling work during dry weather; preserving vegetation and buffers; drainage swales/lined ditches; mulching or hydroseeding; slope protection; inlet protection; perimeter sediment controls; sediment traps/basins; stabilized construction exits; wind erosion control.
  • Good housekeeping BMPs (examples, not exclusive): dewatering controls; material handling and stockpile management; designated washout areas (concrete, paint, stucco); fueling controls and staging; off‑site equipment cleaning; spill prevention and control.

Decision table — key thresholds and required actions

Decision dimension When it applies Required action(s) Code reference
Site disturbance area < 1 acre and not part of larger plan Prevent stormwater pollution by complying with local ordinance or implementing BMPs § 5.106.1
Part of larger common plan Any individual parcel (even < 1 acre) that is part of a plan that in total disturbs ≥ 1 acre Comply with stormwater discharge regulations / NPDES permit requirements § 5.106.2
Site disturbance area ≥ 1 acre Comply with lawfully enacted stormwater discharge regulations; postconstruction hydrology requirements (see NPDES) § 5.106.2
BMP selection Any project covered by § 5.106.1 Implement appropriate combination of soil loss BMPs and good housekeeping BMPs listed in the code § 5.106.1.2

Documentation & enforcement

  • The code requires compliance either by following the local ordinance or implementing BMPs acceptable to the enforcing agency — expect plan notes, BMP locations on drawings, and possibly an erosion-control plan or checklist per the enforcing agency. (See § 5.106.1.1 and § 5.106.1.2.)
  • For projects subject to § 5.106.2, the NPDES General Permit requires postconstruction runoff controls (post-project hydrology matching pre-project conditions) and emphasizes Low Impact Development (LID) and nonstructural controls; structural measures are allowed where nonstructural controls cannot address the volume.

Exceptions & special cases

  • If a project disturbs less than one acre but is part of a larger common plan of development or sale (that in total disturbs ≥ 1 acre), it is not eligible for the <1 acre path — it must follow § 5.106.2 and applicable NPDES/permit requirements.
  • There is no blanket exemption for small projects from local stormwater ordinances — compliance with a local ordinance (if enacted) is an explicit option under § 5.106.1.1.
  • The code lists examples of BMPs but delegates acceptability and detailed requirements to the enforcing agency; local rules or the enforcing agency may require specific measures or documentation. Do not assume the list is exhaustive.

Common mistakes

  • Assuming any project < 1 acre is exempt — if it’s part of a larger common plan, it’s subject to § 5.106.2.
  • Relying on a single BMP that does not address both soil loss and construction housekeeping (the code expects an effective combination as needed).
  • Failing to check or follow a local stormwater/erosion control ordinance — compliance with a local ordinance is an explicit path under § 5.106.1.1.
  • Not showing BMPs on plans or in specs for permitting; the enforcing agency may require documentation or plan notes demonstrating the chosen measures.

Worked example — concrete scenario

Scenario: A developer will perform grading and site work on a single lot totaling 0.75 acres for a small commercial addition. The lot is not part of any larger subdivision plan.

  1. Applicability check: 0.75 acres < 1 acre and not part of a larger common plan → follow § 5.106.1 (local ordinance or BMPs).
  2. Verify local rules: check city/county stormwater/erosion control ordinance. If the local ordinance requires a specific erosion-control plan, comply with that as allowed by § 5.106.1.1.
  3. If following BMP route, select an effective combination from § 5.106.1.2. A practical, code-supported set might include:
    • Perimeter silt fence and fiber rolls along downslope boundaries (soil loss BMP).
    • Inlet protection (gravel bags or catch basin inserts) if storm drains are on-site (soil loss BMP).
    • Stabilized construction exit at the site entrance to minimize off-site tracking (soil loss BMP).
    • Designated washout area for concrete and paint with containment (good housekeeping BMP).
    • Spill prevention and fueling controls at the staging area (good housekeeping BMP).
  4. Document on the plans: show BMP locations, maintenance responsibilities, and a brief narrative describing when each BMP will be in place (the enforcing agency will expect this documentation per § 5.106.1).
  5. If during review the enforcing agency or local ordinance requires additional measures or sizing (e.g., a sediment trap), implement those; if the project were part of a larger plan or ≥ 1 acre, follow § 5.106.2 and NPDES requirements instead.

Related provisions

  • § 5.106.1 — Stormwater pollution prevention for projects that disturb less than one acre (BMPs and local ordinance option).
  • § 5.106.1.1 — Compliance with local stormwater management and/or erosion control ordinance.
  • § 5.106.1.2 — Examples of soil loss and good housekeeping BMPs to prevent stormwater pollution.
  • § 5.106.2 — Stormwater pollution prevention for projects that disturb one or more acres of land or are part of a larger common plan (NPDES/postconstruction controls and LID emphasis).

Code references

Grounded in the retrieved California Green Building Standards Code (CALGreen) — click a citation to read the verbatim passage:

  • CALGreen § 5.105.2. High relevance — show source text

    Exception [BSC-CG, DSA-SS]: Combined addition(s) to existing building(s) of two times the area or more of the existing building(s) is not eligible to meet compliance with Section 5.105.2.

    5.105.2 Reuse of existing building. An alteration or addition to an existing building shall maintain at a minimum 45 percent combined of the existing building’s primary structural elements (foundations; columns, beams, walls, and floors; and lateral elements) and existing building enclosure (roof framing, wall framing and exterior finishes). Window assemblies, insulation, portions of buildings deemed structurally unsound or hazardous, and hazardous materials that are remediated as part of the project shall not be included in the calculation.

    5.105.2.1 Verification of compliance. Documentation shall be provided in the construction documents to demonstrate compliance with Section 5.105.2.

    Note: Sample Worksheet WS-3 in Chapter 8 may be used to assist in documenting compliance with this section.

    5.105.3 Deconstruction (Reserved).

    SECTION 5.106—SITE DEVELOPMENT

    5.106.1 Stormwater pollution prevention for projects that disturb less than one acre of land. Newly constructed projects and additions which disturb less than one acre of land and are not part of a larger common plan of development or sale shall prevent the pollution of stormwater runoff from the construction activities through one or more of the following measures:

    5.106.1.1 Local ordinance. Comply with a lawfully enacted stormwater management and/or erosion control ordinance.

    5.106.1.2 Best management practices (BMP’s). Prevent the loss of soil through wind or water erosion by implementing an effective combination of erosion and sediment control and good housekeeping BMP’s.

    1. Soil loss BMP’s that should be considered for implementation as appropriate for each project include, but are not limited to, the following: a. Scheduling construction activity during dry weather, when possible. b. Preservation of natural features, vegetation, soil and buffers around surface waters. c. Drainage swales or lined ditches to control stormwater flow. d. Mulching or hydroseeding to stabilize disturbed soils. e. Erosion control to protect slopes.

    2025 CALIFORNIA GREEN BUILDING STANDARDS CODE 5-3

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

    NONRESIDENTIAL MANDATORY MEASURES

    f. Protection of storm drain inlets (gravel bags or catch basin inserts). g. Perimeter sediment control (perimeter silt fence, fiber rolls). h. Sediment trap or sediment basin to retain sediment on site.

    i. Stabilized construction exits.

    j. Wind erosion control. k. Other soil loss BMP’s acceptable to the enforcing agency. 2. Good housekeeping BMP’s to manage construction equipment, materials, non-stormwater discharges and wastes that should be considered for implementation as appropriate for each project include, but are not limited to, the following: a. Dewatering activities. b. Material handling and waste management. c. Building materials stockpile management. d. Management of washout areas (concrete, paints, stucco, etc.). e. Control of vehicle/equipment fueling to contractor’s staging area. f. Vehicle and equipment cleaning performed off site. g. Spill prevention and control. h. Other housekeeping BMP’s acceptable to the enforcing agency.

  • CALGreen § 4-1 High relevance — show source text

    The state agency does not adopt sections identified by the following symbol: †.

    2025 CALIFORNIA GREEN BUILDING STANDARDS CODE 4-1

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

    4-2 2025 CALIFORNIA GREEN BUILDING STANDARDS CODE

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

    4 RESIDENTIAL MANDATORY MEASURES

    DIVISION 4.1 – PLANNING AND DESIGN

    SECTION 4.101—GENERAL

    4.101.1 Scope. The provisions of this division outline planning, design and development methods that include environmentally responsible site selection, building design, building siting and development to protect, restore and enhance the environmental quality of the site and respect the integrity of adjacent properties.

    SECTION 4.102—DEFINITIONS

    4.102.1 Definitions. The following terms are defined in Chapter 2.

    FRENCH DRAIN.

    WATTLES.

    SECTION 4.103—SITE SELECTION (RESERVED)

    SECTION 4.104—SITE PRESERVATION (RESERVED)

    SECTION 4.105—DECONSTRUCTION AND REUSE OF EXISTING STRUCTURES (RESERVED)

    SECTION 4.106—SITE DEVELOPMENT

    4.106.1 General. Preservation and use of available natural resources shall be accomplished through evaluation and careful planning to minimize negative effects on the site and adjacent areas. Preservation of slopes, management of storm water drainage and erosion controls shall comply with this section.

    4.106.2 Storm water drainage and retention during construction. Projects which disturb less than one acre of soil and are not part of a larger common plan of development which in total disturbs one acre or more, shall manage storm water drainage during construction. In order to manage storm water drainage during construction, one or more of the following measures shall be implemented to prevent flooding of adjacent property, prevent erosion and retain soil runoff on the site.

    1. Retention basins of sufficient size shall be utilized to retain storm water on the site.

    2. Where storm water is conveyed to a public drainage system, collection point, gutter or similar disposal method, water shall be filtered by use of a barrier system, wattle or other method approved by the enforcing agency.

    3. Compliance with a lawfully enacted storm water management ordinance.

    Note: Refer to the State Water Resources Control Board for projects which disturb one acre or more of soil, or are part of a larger common plan of development which in total disturbs one acre or more of soil.

    (Website: https://www.waterboards.ca.gov/water_issues/programs/stormwater/construction.html)

    4.106.3 Grading and paving. Construction plans shall indicate how the site grading or drainage system will manage all surface water flows to keep water from entering buildings. Examples of methods to manage surface water include, but are not limited to, the following:

    1. Swales

    2. Water collection and disposal systems

    3. French drains

    4. Water retention gardens

    5. Other water measures which keep surface water away from buildings and aid in groundwater recharge.

    Exception: Additions and alterations not altering the drainage path.

  • CALGreen § 301.3 High relevance — show source text

    A5.602

    CALGreen VERIFICATION GUIDELINES MANDATORY MEASURES CHECKLIST

    Application: This checklist shall be used for nonresidential projects that meet one of the following: new construction, building additions of 1,000 square feet or greater, or building alterations with a permit valuation of $200,000 or more pursuant to Section 301.3 AND do not trigger a Tier 1 or Tier 2 requirement:

    Y = Yes (section has been selected and/or included)

    — N/A = Not Applicable (code section does not apply to the project mainly used for additions and alterations) O = Other (provide explanation)

    [N] = New construction pursuant to Section 301.3

    [A ] = Additions and/or Alterations pursuant to Section 301.3

    CHAPTER 5
    DIVISIONS    		 Col2 SECTION TITLE CODE
    SECTION    		 Y N/A O PLAN SHEET,
    SPEC OR
    ATTACH
    DIVISION 5.1
    Planning and
    Design    		 Mandatory Deconstruction and reuse of existing structures,
    Scope with Exception    		 5.105.1
    DIVISION 5.1
    Planning and
    Design    		 Mandatory Reuse of existing building & Verification of compliance with
    note    		 5.105.2 and
    5.105.2.1
    DIVISION 5.1
    Planning and
    Design    		 Mandatory Storm water pollution prevention for projects that disturb less
    than 1 acre of land    		 5.106.1 through
    5.106.2
    DIVISION 5.1
    Planning and
    Design    		 Mandatory Short-term bicycle parking (with exception) 5.106.4.1.1
    DIVISION 5.1
    Planning and
    Design    		 Mandatory Long-term bicycle parking 5.106.4.1.2
    through
    5.106.4.1.2.3
    DIVISION 5.1
    Planning and
    Design    		 Mandatory Electric vehicle (EV) charging [N] with Section 5.106.3.1,
    5.106.5.3.2 and associated Table 5.106.5.3.1
    OR Independently
    Power Allocation Method:
    Section 5.106.5.3.6 and associated Table 5.106.5.3.6    		 5.106.5.3.1,
    5.106.5.3.2,
    Table 5.106.5.3.1,
    5.106.5.3.2.1,
    5.106.5.3.2.2,
    5.106.5.3.2.3,
    5.106.5.3.2.4,
    5.106.5.3.3,
    5.106.5.3.4 and
    5.106.5.3.5
    OR
    5.106.5.3.3,
    5.106.5.3.4,
    5.106.5.3.5,
    5.106.5.3.6,
  • CALGreen § 5-3 High relevance — show source text

    2025 CALIFORNIA GREEN BUILDING STANDARDS CODE 5-3

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

    NONRESIDENTIAL MANDATORY MEASURES

    f. Protection of storm drain inlets (gravel bags or catch basin inserts). g. Perimeter sediment control (perimeter silt fence, fiber rolls). h. Sediment trap or sediment basin to retain sediment on site.

    i. Stabilized construction exits.

    j. Wind erosion control. k. Other soil loss BMP’s acceptable to the enforcing agency. 2. Good housekeeping BMP’s to manage construction equipment, materials, non-stormwater discharges and wastes that should be considered for implementation as appropriate for each project include, but are not limited to, the following: a. Dewatering activities. b. Material handling and waste management. c. Building materials stockpile management. d. Management of washout areas (concrete, paints, stucco, etc.). e. Control of vehicle/equipment fueling to contractor’s staging area. f. Vehicle and equipment cleaning performed off site. g. Spill prevention and control. h. Other housekeeping BMP’s acceptable to the enforcing agency.

    5.106.2 Stormwater pollution prevention for projects that disturb one or more acres of land. Comply with all lawfully enacted stormwater discharge regulations for projects that (1) disturb one acre or more of land, or (2) disturb less than one acre of land but are part of a larger common plan of development or sale.

    Note: Projects that (1) disturb one acre or more of land, or (2) disturb less than one acre of land but are part of a larger common plan of development or sale must comply with the postconstruction requirements detailed in the applicable National Pollutant Discharge Elimination System (NPDES) General Permit for Stormwater Discharges Associated with Construction and Land Disturbance Activities issued by the State Water Resources Control Board or the Lahontan Regional Water Quality Control Board (for projects in the Lake Tahoe Hydrologic Unit).

    The NPDES permits require postconstruction runoff (post-project hydrology) to match the preconstruction runoff (pre-project hydrology) with the installation of postconstruction stormwater management measures. The NPDES permits emphasize runoff reduction through on-site stormwater use, interception, evapotranspiration and infiltration through nonstructural controls, such as Low Impact Development (LID) practices and conservation design measures. Stormwater volume that cannot be addressed using nonstructural practices is required to be captured in structural practices and be approved by the enforcing agency.

    Refer to the current applicable permits on the State Water Resources Control Board website at: www.waterboards.ca.gov/constructionstormwater. Consideration to the stormwater runoff management measures should be given during the initial design process for appropriate integration into site development.

    5.106.3 Reserved.

    5.106.4 Bicycle parking. For buildings within the authority of California Building Standards Commission as specified in Section 103, comply with Section 5.106.4.1. For buildings within the authority of the Division of the State Architect pursuant to Section 105, comply with Section 5.106.4.2.

    5.106.4.1 Bicycle parking. [BSC-CG] Comply with Sections 5.106.4.1.1 and 5.106.4.1.2; or meet the applicable local ordinance, whichever is stricter.

  • CALGreen § 5.103 High relevance — show source text

    ZEV.

    SECTION 5.103—SITE SELECTION (RESERVED)

    SECTION 5.104—SITE PRESERVATION (RESERVED)

    SECTION 5.105—DECONSTRUCTION AND REUSE OF EXISTING STRUCTURES

    5.105.1 Scope.

    [BSC-CG] Effective July 1, 2024, alteration(s) to existing building(s) where the combined altered floor area is 100,000 square feet or greater shall comply with either Section 5.105.2, 5.409.2, or 5.409.3. Addition(s) to existing building(s) where the total floor area combined with the existing building(s) is 100,000 square feet or greater shall comply with either Section 5.105.2, Section 5.409.2, or Section 5.409.3. Effective January 1, 2026, the combined floor area shall be 50,000 square feet or greater.

    [DSA-SS] Alteration(s) to existing building(s) where the combined altered floor area is 50,000 square feet or greater shall comply with either Section 5.105.2, 5.409.2, or 5.409.3. Addition(s) to existing building(s) where the total floor area combined with the existing building(s) is 50,000 square feet or greater shall comply with either Section 5.105.2, Section 5.409.2, or Section 5.409.3.

    Exception [BSC-CG, DSA-SS]: Combined addition(s) to existing building(s) of two times the area or more of the existing building(s) is not eligible to meet compliance with Section 5.105.2.

    5.105.2 Reuse of existing building. An alteration or addition to an existing building shall maintain at a minimum 45 percent combined of the existing building’s primary structural elements (foundations; columns, beams, walls, and floors; and lateral elements) and existing building enclosure (roof framing, wall framing and exterior finishes). Window assemblies, insulation, portions of buildings deemed structurally unsound or hazardous, and hazardous materials that are remediated as part of the project shall not be included in the calculation.

    5.105.2.1 Verification of compliance. Documentation shall be provided in the construction documents to demonstrate compliance with Section 5.105.2.

    Note: Sample Worksheet WS-3 in Chapter 8 may be used to assist in documenting compliance with this section.

    5.105.3 Deconstruction (Reserved).

    SECTION 5.106—SITE DEVELOPMENT

    5.106.1 Stormwater pollution prevention for projects that disturb less than one acre of land. Newly constructed projects and additions which disturb less than one acre of land and are not part of a larger common plan of development or sale shall prevent the pollution of stormwater runoff from the construction activities through one or more of the following measures:

    5.106.1.1 Local ordinance. Comply with a lawfully enacted stormwater management and/or erosion control ordinance.

  • CALGreen § 301.3 High relevance — show source text

    Y = Yes (section has been selected and/or included) N = No (section has not been selected and/or included) O = Other (provide explanation)

    [N] = New construction pursuant to Section 301.3

    [A] = Additions and/or Alterations pursuant to Section 301.3

    CHAPTER 5
    DIVISIONS    		 Col2 SECTION TITLE CODE
    SECTION    		 Y N O PLAN SHEET,
    SPEC OR
    ATTACH
    DIVISION 5.1
    Planning and
    Design
    (continued)    		 Mandatory Deconstruction and reuse of existing structures,
    Scope with Exception    		 5.105.1
    DIVISION 5.1
    Planning and
    Design
    (continued)    		 Mandatory Reuse of existing building & Verification of compliance with note 5.105.2 and 5.105.2.1
    DIVISION 5.1
    Planning and
    Design
    (continued)    		 Mandatory Storm water pollution prevention for projects that disturb
    less than 1 acre of land    		 5.106.1 through
    5.106.2
    DIVISION 5.1
    Planning and
    Design
    (continued)    		 Mandatory Short-term bicycle parking 5.106.4.1.1
    DIVISION 5.1
    Planning and
    Design
    (continued)    		 Mandatory Long-term bicycle parking 5.106.4.1.2 through
    5.106.4.1.5
    DIVISION 5.1
    Planning and
    Design
    (continued)    		 Tier 1
    Prerequisite    		 Designated parking—35% of parking capacity with future
    charging spaces, parking stall markings and vehicle
    designation    		 A5.106.5.1,
    A5.106.5.1.1,
    A5.106.5.1.3,
    A5.106.5.1.4,
    A5.106.5.1.5
    DIVISION 5.1
    Planning and
    Design
    (continued)    		 Tier 1
    Prerequisite    		 Electric vehicle (EV) charging [N] with Section 5.106.3.1, Section
    5.106.5.3.2 and associated Table A5.106.5.3.1 Tier 1
    OR
    Power Allocation Method:
    Section A5.106.5.3.2 and associated Table A5.106.5.3.2 Tier 1    		 5.106.5.3.1,
    5.106.5.3.2,
    Table A5.106.5.3.1 Tier
    1, 5.106.5.3.2.1,
    5.106.5.3.2.2,
    5.106.5.3.2.3,
    5.106.5.3.2.4,
    _5.106.5.3.3,
  • CALGreen § 301.3 High relevance — show source text

    Select the required number of additional electives from those categories shown on the table below and add a “ Y ” on the selected elective and add an “ N ” on the rest.

    Count the total number of Tier 2 prerequisite measures plus the additional electives and write down the total number at the end of the checklist. Determine if the required number of Tier 2 measures have been selected to achieve Tier 2 compliance.

    Y = Yes (section has been selected and/or included) N = No (section has not been selected and/or included) O = Other (provide explanation)

    [N] = New construction pursuant to Section 301.3

    [A] = Additions and/or Alterations pursuant to Section 301.3

    CHAPTER 5
    DIVISIONS    		 Col2 SECTION TITLE CODE
    SECTION    		 Y N O PLAN SHEET,
    SPEC OR
    ATTACH
    DIVISION 5.1
    Planning and
    Design
    (continued)    		 Mandatory Deconstruction and reuse of existing structures,
    Scope with Exception    		 5.105.1
    DIVISION 5.1
    Planning and
    Design
    (continued)    		 Mandatory Reuse of existing building & Verification of compliance with
    note    		 5.105.2 and 5.105.2.1
    DIVISION 5.1
    Planning and
    Design
    (continued)    		 Mandatory Storm water pollution prevention for projects that disturb
    less than 1 acre of land    		 5.106.1 through
    5.106.2
    DIVISION 5.1
    Planning and
    Design
    (continued)    		 Mandatory Short-term bicycle parking 5.106.4.1.1
    DIVISION 5.1
    Planning and
    Design
    (continued)    		 Mandatory Long-term bicycle parking 5.106.4.1.2 through
    5.106.4.1.5
    DIVISION 5.1
    Planning and
    Design
    (continued)    		 Tier 2
    Prerequisite    		 Designated parking—50% of parking capacity with future
    charging spaces, parking stall markings and vehicle
    designation    		 A5.106.5.1,
    A5.106.5.1.2,
    A5.106.5.1.3,
    A5.106.5.1.4,
    A5.106.5.1.5
    DIVISION 5.1
    Planning and
    Design
    (continued)    		 Tier 2
    Prerequisite    		 Electric vehicle (EV) charging [N] with Section 5.106.3.1,
    Section 5.106.5.3.2 and associated Table A5.106.5.3.3 Tier 2
    OR
    Power Allocation Method:
    Section A5.106.5.3.4 and associated Table A5.106.5.3.4 Tier 2    		 5.106.5.3.1,
    5.106.5.3.2,
    _Table A5.106.5.
  • CALGreen § 4.106.2 High relevance — show source text

    4.106.2 Storm water drainage and retention during construction. Projects which disturb less than one acre of soil and are not part of a larger common plan of development which in total disturbs one acre or more, shall manage storm water drainage during construction. In order to manage storm water drainage during construction, one or more of the following measures shall be implemented to prevent flooding of adjacent property, prevent erosion and retain soil runoff on the site.

    1. Retention basins of sufficient size shall be utilized to retain storm water on the site.

    2. Where storm water is conveyed to a public drainage system, collection point, gutter or similar disposal method, water shall be filtered by use of a barrier system, wattle or other method approved by the enforcing agency.

    3. Compliance with a lawfully enacted storm water management ordinance.

    Note: Refer to the State Water Resources Control Board for projects which disturb one acre or more of soil, or are part of a larger common plan of development which in total disturbs one acre or more of soil.

    (Website: https://www.waterboards.ca.gov/water_issues/programs/stormwater/construction.html)

    4.106.3 Grading and paving. Construction plans shall indicate how the site grading or drainage system will manage all surface water flows to keep water from entering buildings. Examples of methods to manage surface water include, but are not limited to, the following:

    1. Swales

    2. Water collection and disposal systems

    3. French drains

    4. Water retention gardens

    5. Other water measures which keep surface water away from buildings and aid in groundwater recharge.

    Exception: Additions and alterations not altering the drainage path.

    4.106.4 Electric vehicle (EV) charging for new construction. New construction shall comply with Section 4.106.4.1 or 4.106.4.2. Electric vehicle supply equipment (EVSE) shall comply with the California Electrical Code.

    Exceptions:

    1. On a case-by-case basis, where the local enforcing agency has determined EV charging and infrastructure are not feasible based upon one or more of the following conditions: 1.1. Where there is no local utility power supply or the local utility is unable to supply adequate power.

    2025 CALIFORNIA GREEN BUILDING STANDARDS CODE 4-3

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

    RESIDENTIAL MANDATORY MEASURES

    1.2. Where there is evidence suitable to the local enforcing agency substantiating that additional local utility infrastructure design requirements, directly related to the implementation of Section 4.106.4, may adversely impact the construction cost of the project. 2. Accessory Dwelling Units (ADU) and Junior Accessory Dwelling Units (JADU) without additional parking facilities.

  • CALGreen § 405.4 High relevance — show source text
    1. From Division A5.4,

    a. Comply with recycled content of 15 percent of materials based on estimated total cost, or use two products from Table A5.405.4 for at least 75 percent by cost in Section A5.405.4.1. b. Comply with the 80-percent reduction in construction and demolition waste in Section A5.408.3.1. c. Comply with three elective measures selected from this division.

    1. From Division A5.5,

    a. Comply with resilient flooring systems for 100 percent of resilient flooring in Section A5.504.4.7.1. Exception: Allowance may be permitted in Tier 2 for up to 5-percent specialty purpose flooring. b. Comply with thermal insulation meeting 2009 CHPS low-emitting materials list and no added formaldehyde in Section A5.504.4.8.1.

    c. Comply with three elective measures selected from this division. 6. Comply with three additional elective measures selected from any division.

    1 Cool roof is required for compliance with Tiers 1 and 2 and may be used to meet energy standards in Part 6, exceed energy standards and to mitigate heat island effect.

    A5.601.4 Compliance verification. Compliance with Section A5.601.2 or A5.601.3 shall be as required in Chapter 7 of this code. Compliance documentation shall be made part of the project record as required in Section 5.410.2 or 5.410.3.

    2025 CALIFORNIA GREEN BUILDING STANDARDS CODE APPENDIX A5-43

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

    APPENDIX A5 — NONRESIDENTIAL VOLUNTARY MEASURES

    A5.602

    CALGreen VERIFICATION GUIDELINES MANDATORY MEASURES CHECKLIST

    Application: This checklist shall be used for nonresidential projects that meet one of the following: new construction, building additions of 1,000 square feet or greater, or building alterations with a permit valuation of $200,000 or more pursuant to Section 301.3 AND do not trigger a Tier 1 or Tier 2 requirement:

    Y = Yes (section has been selected and/or included)

    — N/A = Not Applicable (code section does not apply to the project mainly used for additions and alterations) O = Other (provide explanation)

    [N] = New construction pursuant to Section 301.3

    [A ] = Additions and/or Alterations pursuant to Section 301.3

    CHAPTER 5
    DIVISIONS    		 Col2 SECTION TITLE CODE
    SECTION    		 Y N/A O PLAN SHEET,
    SPEC OR
    ATTACH
    DIVISION 5.1
    Planning and
    Design    		 Mandatory Deconstruction and reuse of existing structures,
    Scope with Exception    		 5.105.1
    DIVISION 5.1
    Planning and
    Design    		 Mandatory Reuse of existing building & Verification of compliance with
    note    		 5.105.2 and
    5.105.2.1
    DIVISION 5.1
    Planning and
    Design    		 Mandatory Storm water pollution prevention for projects that disturb less
    than 1 acre of land    		 5.106.
  • CALGreen § 5.508.2 High relevance — show source text

    000 square feet or more|5.508.2
    through
    5.508.2.6.3||||| |||END OF MANDATORY PROVISIONS||||||

    Documentation Author's / Responsible Designer's Declaration Statement
    □ Mandatory: I attest that this mandatory provisions checklist is accurate and complete.    		 Col2
    Signature: Signature:
    Company: Date:
    Address: License:
    City/State/Zip: Phone:

    2025 CALIFORNIA GREEN BUILDING STANDARDS CODE APPENDIX A5-47

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

    APPENDIX A5 — NONRESIDENTIAL VOLUNTARY MEASURES

    A5.602.1

    CALGreen VERIFICATION GUIDELINES

    TIER 1 CHECKLIST

    Application: This checklist shall be used for nonresidential projects that meet the following: new construction, or building additions of 1,000 square feet or greater, or building alterations with a permit valuation of $200,000 or more pursuant to Section 301.3, AND are adopting Tier 1 voluntary measures.

    Note: All applicable mandatory requirements in Chapter 5 shall be met prior to applying Tier 1 voluntary measures.

    Instructions:

    Comply with all Tier 1 prerequisite measures from the various categories shown on the table below.

    Add a “ Y ” to all mandatory and Tier 1 prerequisite measures in the appropriate columns.

    Select the required number of additional electives from those categories shown on the table below and add a “ Y ” on the selected elective and add an “ N ” on the rest.

    Count the total number of Tier 1 prerequisite measures plus the additional electives and write down the total number at the end of the checklist. Determine if the required number of Tier 1 measures have been selected to achieve Tier 1 compliance.

    Y = Yes (section has been selected and/or included) N = No (section has not been selected and/or included) O = Other (provide explanation)

    [N] = New construction pursuant to Section 301.3

    [A] = Additions and/or Alterations pursuant to Section 301.3

    CHAPTER 5
    DIVISIONS    		 Col2 SECTION TITLE CODE
    SECTION    		 Y N O PLAN SHEET,
    SPEC OR
    ATTACH
    DIVISION 5.1
    Planning and
    Design
    (continued)    		 Mandatory Deconstruction and reuse of existing structures,
    Scope with Exception    		 5.105.1
    DIVISION 5.1
    Planning and
    Design
    (continued)    		 Mandatory Reuse of existing building & Verification of compliance with note 5.105.2 and 5.105.2.1
    DIVISION 5.1
    Planning and
    Design
    (continued)    		 Mandatory Storm water pollution prevention for projects that disturb
    less than 1 acre of land    		 5.106.1 through
    5.106.2
    DIVISION 5.1
    Planning and
    Design
    (continued)    		 Mandatory Short-term bicycle parking 5.106.4.1.
  • CALGreen § 602.2 High relevance — show source text
    Documentation Author's / Responsible Designer's Declaration Statement
    Check the appropriate box(es) for the list below.
    □ Mandatory: I attest that the mandatory provisions checklist is accurate and complete.
    □ Tier 1 compliant: I attest that the total number of voluntary measures selected meet or exceed the total number required
    to achieve Tier 1 compliance.
    □ Partial Tier 1 compliant: I attest that the total number of voluntary measures selected do not meet the total number
    required to achieve Tier 1 compliance: however, partial Tier 1 compliance has been achieved.    		 Col2
    Signature:
    Company: Date:
    Address: License:
    City/State/Zip: Phone:

    APPENDIX A5-54 2025 CALIFORNIA GREEN BUILDING STANDARDS CODE

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

    APPENDIX A5 — NONRESIDENTIAL VOLUNTARY MEASURES

    A5.602.2

    CALGreen VERIFICATION GUIDELINES

    TIER 2 CHECKLIST

    Application: This checklist shall be used for nonresidential projects that meet the following: new construction, or building additions of 1,000 square feet or greater, or building alterations with a permit valuation of $200,000 or more pursuant to Section 301.3, AND are adopting Tier 2 voluntary measures.

    Note: All applicable mandatory requirements in Chapter 5 shall be met prior to applying Tier 2 voluntary measures.

    Instructions:

    Comply with all Tier 2 prerequisite measures from the various categories shown on the table below.

    Add a “ Y ” to all mandatory and Tier 2 prerequisite measures in the appropriate columns.

    Select the required number of additional electives from those categories shown on the table below and add a “ Y ” on the selected elective and add an “ N ” on the rest.

    Count the total number of Tier 2 prerequisite measures plus the additional electives and write down the total number at the end of the checklist. Determine if the required number of Tier 2 measures have been selected to achieve Tier 2 compliance.

    Y = Yes (section has been selected and/or included) N = No (section has not been selected and/or included) O = Other (provide explanation)

    [N] = New construction pursuant to Section 301.3

    [A] = Additions and/or Alterations pursuant to Section 301.3

    CHAPTER 5
    DIVISIONS    		 Col2 SECTION TITLE CODE
    SECTION    		 Y N O PLAN SHEET,
    SPEC OR
    ATTACH
    DIVISION 5.1
    Planning and
    Design
    (continued)    		 Mandatory Deconstruction and reuse of existing structures,
    Scope with Exception    		 5.105.1
    DIVISION 5.1
    Planning and
    Design
    (continued)    		 Mandatory Reuse of existing building & Verification of compliance with
    note    		 5.105.2 and 5.105.2.1
    DIVISION 5.1
    Planning and
    Design
    (continued)    		 Mandatory Storm water pollution prevention for projects that disturb
    less than 1 acre of land    		 5.106.1 through
    5.106.
  • CALGreen § 3304.1.1 Medium relevance — show source text

    3304.1.1 Slope limits. Slopes for permanent fill shall be not steeper than one unit vertical in two units horizontal (50-percent slope). Cut slopes for permanent excavations shall be not steeper than one unit vertical in two units horizontal (50-percent slope). Deviation from the foregoing limitations for cut slopes shall be permitted only upon the presentation of a soil investigation report acceptable to the building official.

    33-4 2025 CALIFORNIA BUILDING CODE

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

    SAFEGUARDS DURING CONSTRUCTION

    3304.1.2 Surcharge. Fill or other surcharge loads shall not be placed adjacent to any building or structure unless such building or structure is capable of withstanding the additional loads caused by the fill or surcharge. Existing footings or foundations that can be affected by any excavation shall be underpinned adequately or otherwise protected against settlement and shall be protected against lateral movement.

    3304.1.3 Footings on adjacent slopes. For footings on adjacent slopes, see Chapter 18.

    3304.1.4 Fill supporting foundations. Fill to be used to support the foundations of any building or structure shall comply with Section 1804.6. Special inspections of compacted fill shall be in accordance with Section 1705.6.

    3304.1.5 [HCD 1] Storm water drainage and retention during construction. Projects which disturb less than one acre of soil and are not part of a larger common plan of development which in total disturbs one acre or more, shall manage storm water drainage during construction in accordance with the California Green Building Standards Code (CALGreen), Chapter 4, Division 4.1.

    SECTION 3305—SANITARY

    3305.1 Facilities required. Sanitary facilities shall be provided during construction, remodeling or demolition activities in accordance with the California Plumbing Code .

    SECTION 3306—PROTECTION OF PEDESTRIANS

    [BS] 3306.1 Protection required. Pedestrians shall be protected during construction, remodeling and demolition activities as required by this chapter and Table 3306.1. Signs shall be provided to direct pedestrian traffic.

    TABLE 3306.1—PROTECTION OF PEDESTRIANS Col2 Col3
    HEIGHT OF CONSTRUCTION DISTANCE FROM CONSTRUCTION TO LOT LINE TYPE OF PROTECTION REQUIRED
    8 feet or less Less than 5 feet Construction railings
    8 feet or less 5 feet or more None
    More than 8 feet Less than 5 feet Barrier and covered walkway
    More than 8 feet 5 feet or more, but not more than one-fourth the height of
    construction    		 Barrier and covered walkway
    More than 8 feet 5 feet or more, but between one-fourth and one-half the height
    of construction    		 Barrier
    More than 8 feet 5 feet or more, but exceeding one-half the height of construction None
    For SI: 1 foot = 304.8 mm. For SI: 1 foot = 304.8 mm. For SI: 1 foot = 304.8 mm.

Frequently asked questions

Does CALGreen set exact sizes for silt fences, basins, or exits?

No — § 5.106.1.2 provides examples of acceptable BMPs (silt fence, sediment traps, stabilized exits, etc.) but defers to the enforcing agency for acceptability and detailed requirements. You must follow local ordinance or the enforcing agency’s sizing/specifications.

If my lot is 0.9 acres but within a recorded subdivision that will total 2 acres, which section applies?

Because the lot is part of a larger common plan of development that disturbs ≥ 1 acre, § 5.106.2 applies; NPDES/permit and postconstruction requirements apply.

Can I simply rely on one BMP (e.g., silt fence) for the entire project?

Not usually. § 5.106.1.2 requires an effective combination of soil loss and good housekeeping BMPs “as appropriate for each project.” Relying on a single measure that doesn’t address all risks is likely insufficient.

Where do I find the NPDES requirements referenced in § 5.106.2?

§ 5.106.2 refers to the applicable NPDES General Permit for Construction and Land Disturbance Activities; the code points you to the State Water Resources Control Board and its construction stormwater pages for current permits.

Does CALGreen require postconstruction hydrology matching for small sites?

Postconstruction hydrology matching is a requirement of the NPDES permits referenced in § 5.106.2 for projects that disturb ≥ 1 acre or are part of a larger plan. Projects only subject to § 5.106.1 (standalone <1 acre) must prevent stormwater pollution during construction (local ordinance or BMPs) but are not given the NPDES postconstruction hydrology language in that section.

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