CRC · California Residential Code

How must the site be graded and surface drainage directed away from foundations?

For a homeowner: the California Residential Code requires that your yard slope away from the house so water doesn’t pool at the foundation — specifically, the ground should drop at least 6 inches within the first 10 feet from the foundation, or where that’s not possible build drains or swales to move water to an approved collection point; nearby paved areas must slope at least 2% away from the building. **§ R401.3**

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Last reviewed: July 6, 2026

What the code requires — 2–4 sentences

The controlling rule is § R401.3: surface drainage must be diverted to a storm sewer, approved point of collection, or otherwise away from the foundation so it “does not create a hazard,” and lots must be graded to drain surface water away from foundation walls. The code prescribes that the grade shall fall not fewer than 6 inches (152 mm) within the first 10 feet (3048 mm) measured from the foundation; where physical barriers prevent that fall, drains or swales must be used, and impervious surfaces within 10 feet of the foundation must be sloped not less than 2 percent away from the building. § R401.3

The single most important rule: keep surface water moving away from the foundation—either by grading the ground down at least 6 inches over the first 10 feet or, if that’s not possible, by building drains or swales that direct water to an approved collection point. § R401.3

Requirements in detail

Basic performance requirement

  • The site must direct surface drainage to a storm sewer conveyance or other approved point of collection that does not create a hazard. § R401.3
  • Grading must ensure water drains away from foundation walls (not toward them). § R401.3

Required slope and distances (decision‑relevant values)

Requirement Threshold / Value When it applies Code Reference
Minimum fall away from foundation 6 inches (152 mm) in the first 10 feet (3048 mm) Standard requirement for lots § R401.3
Minimum slope for impervious surfaces within 10 ft of foundation Not less than 2 percent Sidewalks, driveways, patios, etc., within 10 ft § R401.3 (Exception)
Minimum slope for swales within 10 ft of foundation Not less than 2 percent Where swales are used as the alternative drainage path § R401.3 (Exception)

Notes:

  • The 6 in / 10 ft requirement corresponds to about a 5% slope (6 in ÷ 120 in = 0.05). § R401.3
  • The code requires the final grade; designers must account for probable additional settlement of backfill (see related foundation/soil provisions). § R401.4

Where the code allows alternatives

  • If lot lines, walls, slopes or other physical barriers prohibit providing the 6‑inch drop in 10 feet, the code requires drains or swales to be constructed to ensure drainage away from the structure. § R401.3 (Exception)
  • Impervious surfaces within 10 feet of the foundation have a separate numeric minimum (2%) even when the 6 in / 10 ft fall is provided. § R401.3 (Exception)

Foundation elevation and discharge point (related foundation detail)

  • On graded sites the top of any exterior foundation must extend above the elevation of the street gutter at the point of discharge or the inlet of an approved drainage device by not less than 12 inches (305 mm) plus 2 percent, unless an alternate elevation is approved by the building official demonstrating required drainage is provided. § R403.1.7.3

Exceptions & special cases

  • Exception in § R401.3: when physical constraints (lot lines, walls, slopes, etc.) make the 6 in/10 ft fall impossible, the required remedy is constructing drains or swales to keep water away from the foundation (the code does not allow simply leaving the site as-is). § R401.3 (Exception)
  • Impervious surfaces (e.g., concrete slabs, paved areas) within 10 ft of the foundation must be sloped ≥ 2% away from the building even if the grading elsewhere meets the 6 in/10 ft criterion. § R401.3 (Exception)
  • Foundation elevation relative to street drainage may impose an additional upward elevation requirement (see § R403.1.7.3). If the top-of-foundation elevation or site configuration makes discharge difficult, the building official may require demonstration (or an engineered solution). § R403.1.7.3

If the site has expansive or questionable soils, the code also directs use of soil testing and geotechnical recommendations (see § R401.4) so grading decisions reflect settlement and soil‑behavior risks. § R401.4

Common mistakes

  • Measuring slope from the wrong point: the required fall is measured from the foundation wall outward (first 10 ft), not from the top of finish grade elsewhere. § R401.3
  • Relying on gutters alone to satisfy grading requirements — gutters can convey roof water but do not replace the requirement that lot grading drain away from foundation to an approved collection point. § R401.3
  • Using less than 2% slope on nearby impervious surfaces (e.g., giving only 1% slope on a patio within 10 ft). § R401.3 (Exception)
  • Not accounting for settlement: setting final grade at exact code slope without allowing for expected settlement of backfill can produce an eventual low spot near the foundation. See soil/backfill guidance in § R401.4. § R401.4
  • Allowing concentrated discharge across property lines that exceeds pre‑existing conditions (local ordinances and grading code guidance govern discharge to neighbors). See related grading provisions in the code (R300 series) and local ordinances. § R300.1

Worked example — concrete scenario with numbers

Scenario: New one‑story house. You must shape the lot immediately adjacent to the foundation to keep surface water away.

Step 1 — Straightforward case:

  • Requirement: 6 inches fall in first 10 feet (about 5% slope) away from foundation. § R401.3
  • Implementation: At the foundation wall the finished grade is set at elevation 100.00. At 10 feet away the finished grade must be at 99.50 or lower (100.00 − 0.50 ft = 99.50). That is 6 inches lower across the 10 ft horizontal distance.

Step 2 — Physical barrier case:

  • If a property line or retaining wall exists 6 feet from the foundation and prevents the 10 ft distance, you may not ignore the requirement. Instead construct a swale or drain to carry water away:
    • Build a swale starting at the foundation edge and direct it to an approved collection point (storm inlet or roadside). Swale slope within the first 10 ft must be not less than 2%. For example, over 10 ft a 2% swale slope drops 2.4 inches (0.02 × 120 in = 2.4 in) — acceptable as the local alternative per the Exception in § R401.3, provided the swale effectively removes water away from the structure. § R401.3 (Exception)

Step 3 — Impervious surface detail:

  • If a paved walkway runs adjacent to the foundation within 10 ft, slope it ≥ 2% away from the foundation. For a 6‑ft wide walk that is 72 inches, 2% equals a 1.44 inch drop over the width (72 in × 0.02 = 1.44 in). § R401.3 (Exception)

Step 4 — Check foundation elevation to street gutter:

  • Confirm top of exterior foundation elevation relative to street gutter/inlet per § R403.1.7.3: the top of foundation should typically be ≥ 12 inches (305 mm) plus 2% above the gutter/inlet at the point of discharge, unless an alternate elevation is approved and demonstrated to provide required drainage. § R403.1.7.3

Related provisions

  • § R401.3 — Drainage: surface drainage diverted to storm sewer or approved collection; lots graded to drain away; 6 in in 10 ft requirement (controlling). § R401.3
  • § R401.4 — Soil tests and when a soils investigation is required (affects grading and settlement allowances). § R401.4
  • § R403.1.7.3 — Foundation elevation relative to street gutter or inlet (top of exterior foundation elevation requirement). § R403.1.7.3
  • § R300.1 / R300.2 — Site drainage and stormwater management during construction (planning and temporary controls). § R300.1

Code references

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

  • CRC § 1.1.1 High relevance — show source text

    Exception: The provisions of this chapter shall be permitted to be used for wood foundations only in the following situations:

    1. In buildings that have not more than two floors and a roof.
    2. Where interior basement and foundation walls are constructed at intervals not exceeding 50 feet (15 240 mm) .

    Wood foundations in Seismic Design Category D 0, D 1 or D 2 shall be designed in accordance with accepted engineering practice.

    R401.2 Requirements. Foundation construction shall be capable of accommodating all loads in accordance with Section R301 and of transmitting the resulting loads to the supporting soil. Fill soils that support footings and foundations shall be designed, installed and tested in accordance with accepted engineering practice.

    Note: See Section R301.1.1.1 for limited-density owner-built rural dwellings.

    R401.3 Drainage. Surface drainage shall be diverted to a storm sewer conveyance or other approved point of collection that does not create a hazard. Lots shall be graded to drain surface water away from foundation walls. The grade shall fall not fewer than 6 inches (152 mm) within the first 10 feet (3048 mm).

    Exception: Where lot lines, walls, slopes or other physical barriers prohibit 6 inches (152 mm) of fall within 10 feet (3048 mm), drains or swales shall be constructed to ensure drainage away from the structure. Impervious surfaces within 10 feet (3048 mm) of the building foundation shall be sloped not less than 2 percent away from the building.

    R401.4 Soil tests. Where quantifiable data created by accepted soil science methodologies indicate expansive soils, compressible soils, shifting soils or other questionable soil characteristics are likely to be present, the building official shall determine whether to require a soil test to determine the soil’s characteristics at a particular location. This test shall be done by an approved agency using an approved method. Where the seismic design category in accordance with Section R301.2.2.1 is C or greater and where soil testing is performed, the geotechnical report shall include the determination of the site class and the short-period spectral response acceleration, S DS, in accordance with Section 1613 of the California Building Code . The seismic design category shall be assigned in accordance with Table R301.2.2.1.1.

    R401.4.1 Geotechnical evaluation. In lieu of a complete geotechnical evaluation, the load-bearing values in Table R401.4.1(1) and the soil classifications in Table R401.4.1(2) shall be assumed.

    TABLE R401.4.1(1)—PRESUMPTIVE LOAD-BEARING VALUES OF FOUNDATION MATERIALSa Col2
    ** CLASS OF MATERIAL** ** LOAD-BEARING PRESSURE**
    (pounds per square foot)
    Crystalline bedrock 12,000
    Sedimentary and foliated rock 4,000
    Sandy gravel and/or gravel (GW and GP) 3,000
    Sand, silty sand, clayey sand, silty gravel and clayey gravel (SW, SP, SM, SC, GM and GC) 2,000
    Clay, sandy, silty clay, clayey silt, silt and sandy siltclay (CL, ML, MH and CH) 1,500b
    For SI: 1 pound per square foot = 0.0479 kPa.
    a. Where soil tests are required by Section R401.4, the allowable bearing capacities of the soil shall be part of the recommendations.
    b.
  • CRC § 4.1.1 High relevance — show source text

    2||||X|||||||||||||||||||| |R401.4.1.1 through
    R401.4.1.1.5||||X|||||||||||||||||||| |R404.5.1||||X|||||||||||||||||||| |R408.3||||X|||||||||||||||||||| |R408.4||||X|||||||||||||||||||| |R408.8||||||||||||||||||||X||||

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

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    4 FOUNDATIONS

    User notes:

    About this chapter: Chapter 4 provides requirements for constructing footings and walls for foundations of wood, masonry, concrete and precast concrete. In addition to a foundation’s ability to support the required design loads, this chapter addresses several other factors that can affect foundation performance. These include controlling surface water and subsurface drainage, requiring soil tests where conditions warrant and evaluating proximity to slopes and minimum depth requirements. This chapter also provides requirements to minimize adverse effects of moisture, decay and pests in basements and crawl spaces.

    SECTION R401—GENERAL

    R401.1 Application. The provisions of this chapter shall control the design and construction of the foundation and foundation spaces for buildings. In addition to the provisions of this chapter, the design and construction of foundations in flood hazard areas as established by Table R301.2 shall meet the provisions of Section R306. Wood foundations shall be designed and installed in accordance with AWC PWF.

    Exception: The provisions of this chapter shall be permitted to be used for wood foundations only in the following situations:

    1. In buildings that have not more than two floors and a roof.
    2. Where interior basement and foundation walls are constructed at intervals not exceeding 50 feet (15 240 mm) .

    Wood foundations in Seismic Design Category D 0, D 1 or D 2 shall be designed in accordance with accepted engineering practice.

    R401.2 Requirements. Foundation construction shall be capable of accommodating all loads in accordance with Section R301 and of transmitting the resulting loads to the supporting soil. Fill soils that support footings and foundations shall be designed, installed and tested in accordance with accepted engineering practice.

    Note: See Section R301.1.1.1 for limited-density owner-built rural dwellings.

    R401.3 Drainage. Surface drainage shall be diverted to a storm sewer conveyance or other approved point of collection that does not create a hazard. Lots shall be graded to drain surface water away from foundation walls. The grade shall fall not fewer than 6 inches (152 mm) within the first 10 feet (3048 mm).

    Exception: Where lot lines, walls, slopes or other physical barriers prohibit 6 inches (152 mm) of fall within 10 feet (3048 mm), drains or swales shall be constructed to ensure drainage away from the structure. Impervious surfaces within 10 feet (3048 mm) of the building foundation shall be sloped not less than 2 percent away from the building.

    **R401.4 Soil tests.

  • CRC § 1.7.3 High relevance — show source text

    R403.1.7.3 Foundation elevation. On graded sites, the top of any exterior foundation shall extend above the elevation of the street gutter at point of discharge or the inlet of an approved drainage device not less than 12 inches (305 mm) plus 2 percent. Alternate elevations are permitted subject to the approval of the building official, provided that it can be demonstrated that required drainage to the point of discharge and away from the structure is provided at all locations on the site.

    R403.1.7.4 Alternate setbacks and clearances. Alternate setbacks and clearances are permitted, subject to the approval of the building official. The building official is permitted to require an investigation and recommendation of a qualified engineer to demonstrate that the intent of this section has been satisfied. Such an investigation shall include consideration of material, height of slope, slope gradient, load intensity and erosion characteristics of slope material.

    R403.1.8 Foundations on expansive soils. Foundation and floor slabs for buildings located on expansive soils shall be designed in accordance with Section 1808.6 of the California Building Code .

    Exception: Slab-on-ground and other foundation systems that have performed adequately in soil conditions similar to those encountered at the building site are permitted subject to the approval of the building official.

    R403.1.8.1 Expansive soils classifications. Soils meeting all of the following provisions shall be considered to be expansive, except that tests to show compliance with Items 1, 2 and 3 shall not be required if the test prescribed in Item 4 is conducted:

    1. Plasticity Index (PI) of 15 or greater, determined in accordance with ASTM D4318.

    2. More than 10 percent of the soil particles pass a No. 200 sieve (75 μ m), determined in accordance with ASTM D422.

    3. More than 10 percent of the soil particles are less than 5 micrometers in size, determined in accordance with ASTM D422.

    4. Expansion Index greater than 20, determined in accordance with ASTM D4829.

    R403.2 Footings for wood foundations. Footings for wood foundations shall be in accordance with Figures R403.1(2) and R403.1(3). Gravel shall be washed and well graded. The maximum size stone shall not exceed [3] / 4 inch (19.1 mm). Gravel shall be free from organic, clayey or silty soils. Sand shall be coarse, not smaller than [1] / 16 -inch (1.6 mm) grains and shall be free from organic, clayey or silty soils. Crushed stone shall have a maximum size of [1] / 2 inch (12.7 mm).

    R403.3 Frost-protected shallow foundations. For buildings where the monthly mean temperature of the building is maintained at not less than 64°F (18°C), footings are not required to extend below the frost line where protected from frost by insulation in accordance with Figure R403.3(1) and Table R403.3(1). Foundations protected from frost in accordance with Figure R403.3(1) and Table R403.3(1) shall not be used for unheated spaces such as porches, utility rooms, garages and carports, and shall not be attached to basements or crawl spaces that are not maintained at a minimum monthly mean temperature of 64°F (18°C).

    Materials used below grade for the purpose of insulating footings against frost shall be labeled as complying with ASTM C578.

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  • CRC § 1010.1.4 High relevance — show source text

    1804 A .3 Placement of backfill. The excavation outside the foundation shall be backfilled with soil that is free of organic material, construction debris, cobbles and boulders or with a controlled low-strength material (CLSM). The backfill shall be placed in lifts and compacted in a manner that does not damage the foundation or the waterproofing or dampproofing material.

    Exception: CLSM need not be compacted.

    1804 A .4 Site grading. The ground immediately adjacent to the foundation shall be sloped away from the building at a slope of not less than 1 unit vertical in 20 units horizontal (5-percent slope) for a minimum distance of 10 feet (3048 mm) measured perpendicular to the face of the wall. If physical obstructions or lot lines prohibit 10 feet (3048 mm) of horizontal distance, a 5-percent slope shall be provided to an approved alternative method of diverting water away from the foundation. Swales used for this purpose shall be sloped not less than 2 percent where located within 10 feet (3048 mm) of the building foundation. Impervious surfaces within 10 feet (3048 mm) of the building foundation shall be sloped not less than 2 percent away from the building.

    Exceptions:

    1. Where climatic or soil conditions warrant, the slope of the ground away from the building foundation shall be permitted to be reduced to not less than 1 unit vertical in 48 units horizontal (2-percent slope).
    2. Impervious surfaces shall be permitted to be sloped less than 2 percent where the surface is a door landing or ramp that is required to comply with Section 1010.1.4, 1012.3 or 1012.6.1.

    The procedure used to establish the final ground level adjacent to the foundation shall account for additional settlement of the backfill.

    1804 A .5 Grading and fill in flood hazard areas. In flood hazard areas established in Section 1612 A .3, grading, fill, or both, shall not be approved:

    1. Unless such fill is placed, compacted and sloped to minimize shifting, slumping and erosion during the rise and fall of flood water and, as applicable, wave action.
    2. In floodways, unless it has been demonstrated through hydrologic and hydraulic analyses performed by a registered design professional in accordance with standard engineering practice that the proposed grading or fill, or both, will not result in any increase in flood levels during the occurrence of the design flood.
    3. In coastal high hazard areas, unless such fill is conducted or placed to avoid diversion of water and waves toward any building or structure.
    4. Where design flood elevations are specified but floodways have not been designated, unless it has been demonstrated that the cumulative effect of the proposed flood hazard area encroachment, when combined with all other existing and anticipated flood hazard area encroachment, will not increase the design flood elevation more than 1 foot (305 mm) at any point.

    1804 A .6 Compacted fill material. Where shallow foundations will bear on compacted fill material, the compacted fill shall comply with the provisions of an approved geotechnical report, as set forth in Section 1803 A .

  • CRC § 18-6 High relevance — show source text

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    SOILS AND FOUNDATIONS

    SECTION 1804—EXCAVATION, GRADING AND FILL

    1804.1 Excavation near foundations. Excavation for any purpose shall not reduce vertical or lateral support for any foundation or adjacent foundation without first underpinning or protecting the foundation against detrimental lateral or vertical movement, or both, in accordance with Section 1803.5.7.

    1804.2 Underpinning. Where underpinning is chosen to provide the protection or support of adjacent structures, the underpinning system shall be designed and installed in accordance with provisions of this chapter and Chapter 33.

    1804.2.1 Underpinning sequencing. Underpinning shall be installed in a sequential manner that protects the neighboring structure and the working construction site. The sequence of installation shall be identified in the approved construction documents.

    1804.3 Placement of backfill. The excavation outside the foundation shall be backfilled with soil that is free of organic material, construction debris, cobbles and boulders or with a controlled low-strength material ( CLSM ). The backfill shall be placed in lifts and compacted in a manner that does not damage the foundation or the waterproofing or dampproofing material.

    Exception: CLSM need not be compacted.

    1804.4 Site grading. The ground immediately adjacent to the foundation shall be sloped away from the building at a slope of not less than 1 unit vertical in 20 units horizontal (5-percent slope) for a minimum distance of 10 feet (3048 mm) measured perpendicular to the face of the wall. If physical obstructions or lot lines prohibit 10 feet (3048 mm) of horizontal distance, a 5-percent slope shall be provided to an approved alternative method of diverting water away from the foundation. Swales used for this purpose shall be sloped not less than 2 percent where located within 10 feet (3048 mm) of the building foundation. Impervious surfaces within 10 feet (3048 mm) of the building foundation shall be sloped not less than 2 percent away from the building.

    Exceptions:

    1. Where climatic or soil conditions warrant, the slope of the ground away from the building foundation shall be permitted to be reduced to not less than 1 unit vertical in 48 units horizontal (2-percent slope).
    2. Impervious surfaces shall be permitted to be sloped less than 2 percent where the surface is a door landing or ramp that is required to comply with Section 1010.1.4, 1012.3 or 1012.6.1.

    The procedure used to establish the final ground level adjacent to the foundation shall account for additional settlement of the backfill.

    1804.4.1 [HCD 1] Construction plans. Construction plans shall indicate how the site grading or drainage system will manage all surface water flows to keep water from entering buildings in accordance with the California Green Building Standards Code (CALGreen), Chapter 4, Division 4.1.

    1804.5 Grading and fill in flood hazard areas. In flood hazard areas established in Section 1612.3, grading, fill, or both, shall not be approved:

    1. Unless such fill is placed, compacted and sloped to minimize shifting, slumping and erosion during the rise and fall of flood water and, as applicable, wave action.
  • CRC § 18-16 High relevance — show source text

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    SOILS AND FOUNDATIONS

    1808.6.4 Stabilization. Where the active zone of expansive soils is stabilized in lieu of designing foundations in accordance with Section 1808.6.1 or 1808.6.2, the soil shall be stabilized by chemical, dewatering, presaturation or equivalent techniques.

    1808.7 Foundations on or adjacent to slopes. The placement of buildings and structures on or adjacent to slopes steeper than one unit vertical in three units horizontal (33.3-percent slope) shall comply with Sections 1808.7.1 through 1808.7.5.

    1808.7.1 Building clearance from ascending slopes. In general, buildings below slopes shall be set a sufficient distance from the slope to provide protection from slope drainage, erosion and shallow failures. Except as provided in Section 1808.7.5 and Figure 1808.7.1, the following criteria will be assumed to provide this protection. Where the existing slope is steeper than one unit vertical in one unit horizontal (100-percent slope), the toe of the slope shall be assumed to be at the intersection of a horizontal plane drawn from the top of the foundation and a plane drawn tangent to the slope at an angle of 45 degrees (0.79 rad) to the horizontal. Where a retaining wall is constructed at the toe of the slope, the height of the slope shall be measured from the top of the wall to the top of the slope.

    FIGURE 1808.7.1—FOUNDATION CLEARANCES FROM SLOPES

    For SI: 1 foot = 304.8 mm.

    1808.7.2 Foundation setback from descending slope surface. Foundations on or adjacent to slope surfaces shall be founded in firm material with an embedment and set back from the slope surface sufficient to provide vertical and lateral support for the foundation without detrimental settlement. Except as provided for in Section 1808.7.5 and Figure 1808.7.1, the following setback is deemed adequate to meet the criteria. Where the slope is steeper than 1 unit vertical in 1 unit horizontal (100-percent slope), the required setback shall be measured from an imaginary plane 45 degrees (0.79 rad) to the horizontal, projected upward from the toe of the slope.

    1808.7.3 Pools. The setback between pools regulated by this code and slopes shall be equal to one-half the building footing setback distance required by this section. That portion of the pool wall within a horizontal distance of 7 feet (2134 mm) from the top of the slope shall be capable of supporting the water in the pool without soil support.

    1808.7.4 Foundation elevation. On graded sites, the top of any exterior foundation shall extend above the elevation of the street gutter at point of discharge or the inlet of an approved drainage device not less than 12 inches (305 mm) plus 2 percent. Alternate elevations are permitted subject to the approval of the building official, provided that it can be demonstrated that required drainage to the point of discharge and away from the structure is provided at all locations on the site.

    1808.7.5 Alternate setback and clearance. Alternate setbacks and clearances are permitted, subject to the approval of the building official. The building official shall be permitted to require a geotechnical investigation as set forth in Section 1803.5.10.

  • CRC § 1803A.8 High relevance — show source text

    1803A.8 Geotechnical peer review. [DSA-SS and DSA-SS/CC] When alternate foundations designs or ground improvements are employed or where slope stabilization is required, a qualified peer review by a California-licensed geotechnical engineer, in accordance with Section 322 of Part 10, Title 24, CCR, may be required by the enforcement agency. In Section 322 of Part 10, Title 24, CCR, where reference is made to structural or seismic-resisting system, it shall be replaced with geotechnical, foundation or ground improvement, as appropriate.

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    SOILS AND FOUNDATIONS

    SECTION 1804 A —EXCAVATION, GRADING AND FILL

    1804 A .1 Excavation near foundations. Excavation for any purpose shall not reduce vertical or lateral support for any foundation or adjacent foundation without first underpinning or protecting the foundation against detrimental lateral or vertical movement, or both, in accordance with Section 1803 A .5.7.

    1804 A .2 Underpinning. Where underpinning is chosen to provide the protection or support of adjacent structures, the underpinning system shall be designed and installed in accordance with provisions of this chapter and Chapter 33.

    1804 A .2.1 Underpinning sequencing. Underpinning shall be installed in a sequential manner that protects the neighboring structure and the working construction site. The sequence of installation shall be identified in the approved construction documents.

    1804 A .3 Placement of backfill. The excavation outside the foundation shall be backfilled with soil that is free of organic material, construction debris, cobbles and boulders or with a controlled low-strength material (CLSM). The backfill shall be placed in lifts and compacted in a manner that does not damage the foundation or the waterproofing or dampproofing material.

    Exception: CLSM need not be compacted.

    1804 A .4 Site grading. The ground immediately adjacent to the foundation shall be sloped away from the building at a slope of not less than 1 unit vertical in 20 units horizontal (5-percent slope) for a minimum distance of 10 feet (3048 mm) measured perpendicular to the face of the wall. If physical obstructions or lot lines prohibit 10 feet (3048 mm) of horizontal distance, a 5-percent slope shall be provided to an approved alternative method of diverting water away from the foundation. Swales used for this purpose shall be sloped not less than 2 percent where located within 10 feet (3048 mm) of the building foundation. Impervious surfaces within 10 feet (3048 mm) of the building foundation shall be sloped not less than 2 percent away from the building.

    Exceptions:

    1. Where climatic or soil conditions warrant, the slope of the ground away from the building foundation shall be permitted to be reduced to not less than 1 unit vertical in 48 units horizontal (2-percent slope).
    2. Impervious surfaces shall be permitted to be sloped less than 2 percent where the surface is a door landing or ramp that is required to comply with Section 1010.1.4, 1012.3 or 1012.6.1.
  • CRC § 7.4 High relevance — show source text

    1808 A .7.4 Foundation elevation. On graded sites, the top of any exterior foundation shall extend above the elevation of the street gutter at point of discharge or the inlet of an approved drainage device not less than 12 inches (305 mm) plus 2 percent. Alternate elevations are permitted subject to the approval of the building official, provided that it can be demonstrated that required drainage to the point of discharge and away from the structure is provided at all locations on the site.

    1808 A .7.5 Alternate setback and clearance. Alternate setbacks and clearances are permitted, subject to the approval of the building official. The building official shall be permitted to require a geotechnical investigation as set forth in Section 1803 A .5.10.

    1808 A .8 Concrete foundations. The design, materials and construction of concrete foundations shall comply with Sections 1808 A .8.1 through 1808 A .8.6 and the provisions of Chapter 19 A .

    1808 A .8.1 Concrete or grout strength and mix proportioning. Concrete or grout in foundations shall have a specified compressive strength ( f ′ c ) not less than the largest applicable value indicated in Table 1808 A .8.1.

    Where concrete or grout is to be pumped, the mix design including slump shall be adjusted to produce a pumpable mixture.

    TABLE 1808A.8.1—MINIMUM SPECIFIED COMPRESSIVE STRENGTH f ′ OF CONCRETE OR GROUT
    c    		 Col2
    FOUNDATION ELEMENT OR CONDITION SPECIFIED COMPRESSIVE STRENGTH,****f ′c
    1. Foundations for structures assigned to Seismic Design Category D, E or F 3,000 psi
    2. Precast nonprestressed driven piles 4,000 psi
    3. Socketed drilled shafts 4,000 psi
    4. Micropiles 4,000 psi
    5. Precast prestressed driven piles 5,000 psi
    For SI: 1 pound per square inch = 0.00689 MPa. For SI: 1 pound per square inch = 0.00689 MPa.

    1808 A .8.2 Concrete cover. The concrete cover provided for prestressed and nonprestressed reinforcement in foundations shall be not less than the largest applicable value specified in Table 1808 A .8.2. Longitudinal bars spaced less than 1 [1] / 2 inches (38 mm) clear distance apart shall be considered to be bundled bars for which the concrete cover provided shall be not less than that required by Section 20.5.1.3.5 of ACI 318. Concrete cover shall be measured from the concrete surface to the outermost surface of the steel to which the cover requirement applies. Where concrete is placed in a temporary or permanent casing or a mandrel, the inside face of the casing or mandrel shall be considered to be the concrete surface.

    TABLE 1808A.8.2—MINIMUM CONCRETE COVER Col2
    FOUNDATION ELEMENT OR CONDITION MINIMUM COVER
    1. Shallow foundations In accordance with Section 20.5 of ACI 318
    2.
  • CRC § 7.1 High relevance — show source text

    Where a retaining wall is constructed at the toe of the slope, the height of the slope shall be measured from the top of the wall to the top of the slope.

    FIGURE 1808 A .7.1—FOUNDATION CLEARANCES FROM SLOPES

    For SI: 1 foot = 304.8 mm.

    1808 A .7.2 Foundation setback from descending slope surface. Foundations on or adjacent to slope surfaces shall be founded in firm material with an embedment and set back from the slope surface sufficient to provide vertical and lateral support for the foundation without detrimental settlement. Except as provided for in Section 1808 A .7.5 and Figure 1808 A .7.1, the following setback is deemed adequate to meet the criteria. Where the slope is steeper than 1 unit vertical in 1 unit horizontal (100-percent slope), the required setback shall be measured from an imaginary plane 45 degrees (0.79 rad) to the horizontal, projected upward from the toe of the slope.

    18A-12 2025 CALIFORNIA BUILDING CODE

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    SOILS AND FOUNDATIONS

    1808 A .7.3 Pools. The setback between pools regulated by this code and slopes shall be equal to one-half the building footing setback distance required by this section. That portion of the pool wall within a horizontal distance of 7 feet (2134 mm) from the top of the slope shall be capable of supporting the water in the pool without soil support.

    1808 A .7.4 Foundation elevation. On graded sites, the top of any exterior foundation shall extend above the elevation of the street gutter at point of discharge or the inlet of an approved drainage device not less than 12 inches (305 mm) plus 2 percent. Alternate elevations are permitted subject to the approval of the building official, provided that it can be demonstrated that required drainage to the point of discharge and away from the structure is provided at all locations on the site.

    1808 A .7.5 Alternate setback and clearance. Alternate setbacks and clearances are permitted, subject to the approval of the building official. The building official shall be permitted to require a geotechnical investigation as set forth in Section 1803 A .5.10.

    1808 A .8 Concrete foundations. The design, materials and construction of concrete foundations shall comply with Sections 1808 A .8.1 through 1808 A .8.6 and the provisions of Chapter 19 A .

    1808 A .8.1 Concrete or grout strength and mix proportioning. Concrete or grout in foundations shall have a specified compressive strength ( f ′ c ) not less than the largest applicable value indicated in Table 1808 A .8.1.

    Where concrete or grout is to be pumped, the mix design including slump shall be adjusted to produce a pumpable mixture.

  • CRC § 1808.7.2 High relevance — show source text

    1808.7.2 Foundation setback from descending slope surface. Foundations on or adjacent to slope surfaces shall be founded in firm material with an embedment and set back from the slope surface sufficient to provide vertical and lateral support for the foundation without detrimental settlement. Except as provided for in Section 1808.7.5 and Figure 1808.7.1, the following setback is deemed adequate to meet the criteria. Where the slope is steeper than 1 unit vertical in 1 unit horizontal (100-percent slope), the required setback shall be measured from an imaginary plane 45 degrees (0.79 rad) to the horizontal, projected upward from the toe of the slope.

    1808.7.3 Pools. The setback between pools regulated by this code and slopes shall be equal to one-half the building footing setback distance required by this section. That portion of the pool wall within a horizontal distance of 7 feet (2134 mm) from the top of the slope shall be capable of supporting the water in the pool without soil support.

    1808.7.4 Foundation elevation. On graded sites, the top of any exterior foundation shall extend above the elevation of the street gutter at point of discharge or the inlet of an approved drainage device not less than 12 inches (305 mm) plus 2 percent. Alternate elevations are permitted subject to the approval of the building official, provided that it can be demonstrated that required drainage to the point of discharge and away from the structure is provided at all locations on the site.

    1808.7.5 Alternate setback and clearance. Alternate setbacks and clearances are permitted, subject to the approval of the building official. The building official shall be permitted to require a geotechnical investigation as set forth in Section 1803.5.10.

    1808.8 Concrete foundations. The design, materials and construction of concrete foundations shall comply with Sections 1808.8.1 through 1808.8.6 and the provisions of Chapter 19.

    Exception: [OSHPD 1R, 2 & 5] Not permitted by OSHPD. Where concrete footings supporting walls of light-frame construction are designed in accordance with Table 1809.7, a specific design in accordance with Chapter 19 is not required.

    1808.8.1 Concrete or grout strength and mix proportioning. Concrete or grout in foundations shall have a specified compressive strength ( f ′ c ) not less than the largest applicable value indicated in Table 1808.8.1.

    Where concrete or grout is to be pumped, the mix design including slump shall be adjusted to produce a pumpable mixture.

    TABLE 1808.8.1—MINIMUM SPECIFIED COMPRESSIVE STRENGTH f ′ OF CONCRETE OR GROUT
    c    		 Col2
    FOUNDATION ELEMENT OR CONDITION SPECIFIED COMPRESSIVE STRENGTH,****f ′c
    1. Foundations for structures assigned to Seismic Design Category A, B or C
    [OSHPD 1R, 2 & 5]Not permitted by OSHPD.    		 2,500 psi
    2a. Foundations for Group R or U occupancies of light-frame construction, two stories or less in height,
    assigned to Seismic Design Category D, E or F**_ [OSHPD 1R, 2 & 5]_**Not permitted by OSHPD.    		 2,500 psi
    2b.
  • CRC § 1010.1.4 High relevance — show source text

    Exceptions:

    1. Where climatic or soil conditions warrant, the slope of the ground away from the building foundation shall be permitted to be reduced to not less than 1 unit vertical in 48 units horizontal (2-percent slope).
    2. Impervious surfaces shall be permitted to be sloped less than 2 percent where the surface is a door landing or ramp that is required to comply with Section 1010.1.4, 1012.3 or 1012.6.1.

    The procedure used to establish the final ground level adjacent to the foundation shall account for additional settlement of the backfill.

    1804.4.1 [HCD 1] Construction plans. Construction plans shall indicate how the site grading or drainage system will manage all surface water flows to keep water from entering buildings in accordance with the California Green Building Standards Code (CALGreen), Chapter 4, Division 4.1.

    1804.5 Grading and fill in flood hazard areas. In flood hazard areas established in Section 1612.3, grading, fill, or both, shall not be approved:

    1. Unless such fill is placed, compacted and sloped to minimize shifting, slumping and erosion during the rise and fall of flood water and, as applicable, wave action.
    2. In floodways, unless it has been demonstrated through hydrologic and hydraulic analyses performed by a registered design professional in accordance with standard engineering practice that the proposed grading or fill, or both, will not result in any increase in flood levels during the occurrence of the design flood.
    3. In coastal high hazard areas, unless such fill is conducted or placed to avoid diversion of water and waves toward any building or structure.
    4. Where design flood elevations are specified but floodways have not been designated, unless it has been demonstrated that the cumulative effect of the proposed flood hazard area encroachment, when combined with all other existing and anticipated flood hazard area encroachment, will not increase the design flood elevation more than 1 foot (305 mm) at any point.

    1804.6 Compacted fill material. Where shallow foundations will bear on compacted fill material, the compacted fill shall comply with the provisions of an approved geotechnical report, as set forth in Section 1803.

    Exception: Compacted fill material 12 inches (305 mm) in depth or less need not comply with an approved report, provided that the in-place dry density is not less than 90 percent of the maximum dry density at optimum moisture content determined in accordance with ASTM D1557. The compaction shall be verified by special inspection in accordance with Section 1705.6.

    1804.7 Controlled low-strength material (CLSM). Where shallow foundations will bear on controlled low-strength material (CLSM), the CLSM shall comply with the provisions of an approved geotechnical report, as set forth in Section 1803.

    SECTION 1805—DAMPPROOFING AND WATERPROOFING

    1805.1 General. Walls or portions thereof that retain earth and enclose interior spaces and floors below grade shall be waterproofed and dampproofed in accordance with this section, with the exception of those spaces containing groups other than residential and institutional where such omission is not detrimental to the building or occupancy.

    Ventilation for crawl spaces shall comply with Section 1202.4.

  • CRC § 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

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    4-2 2025 CALIFORNIA GREEN BUILDING STANDARDS CODE

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    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.

Frequently asked questions

Can I rely on roof gutters to satisfy the grading requirement?

No. Gutters and downspouts manage roof discharge but do not replace the requirement that the lot be graded to drain surface water away from foundation walls or that an approved collection point be provided. § R401.3

Where exactly is the 6‑inch drop measured from?

The fall is measured outward from the foundation walls—6 inches (152 mm) lower at 10 feet (3048 mm) from the foundation face is the standard measurement. § R401.3

My lot line is 8 feet from the foundation—what must I do?

If you cannot provide the 6 in/10 ft fall because of the lot line, you must construct drains or swales to ensure drainage away from the structure; swales within 10 ft must be sloped at least 2%. § R401.3 (Exception)

How steep is 6 inches in 10 feet in percent?

6 inches over 10 feet equals roughly 5% slope (6 in ÷ 120 in = 0.05). § R401.3

Do I need a soils report to set final grading elevations?

Not always—but § R401.4 requires soil testing where questionable soils are likely; soil reports influence settlement allowances and final grade decisions adjacent to foundations. § R401.4

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