CBC · California Building Code

How do I determine required load combinations for design?

The CBC requires designers to use ASCE 7 strength combinations (§2.3) for strength design or allowable‑stress combinations from ASCE 7 §2.4 or the CBC’s alternative ASD in §1605.2. CBC §1605.1 lists exceptions (e.g., roof snow thresholds and crane loads) and §1605.2 gives alternate ASD formulas and special rules (dead load reduction for wind, required zeroed‑variable checks, and foundation notes). Follow the referenced CBC sections and ASCE 7 definitions for correct application.

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Last reviewed: July 5, 2026

What the code requires — 2–4 sentences

The California Building Code requires that structures be designed using one of the recognized sets of load combinations: strength (factored / LRFD) combinations in ASCE 7 §2.3, allowable‑stress (ASD) combinations in ASCE 7 §2.4, or the CBC’s alternative allowable‑stress combinations in CBC § 1605.2. Use the ASCE 7 strength combinations when designing for strength (limit states); use ASCE 7 §2.4 or CBC § 1605.2 when using allowable‑stress procedures — and always follow the CBC exceptions and the ASCE 7 modifications referenced by the CBC. See CBC § 1605 and § 1605.1 for the controlling requirement and exceptions, and CBC § 1605.2 for the CBC’s alternative ASD combinations (CBC § 1605 § 1605.1 § 1605.2) .

Requirements in detail

Which combination set to use

  • Strength (factored) combinations: use the strength (limit‑state/LRFD) load combinations specified in ASCE 7, Section 2.3 when designing to strength/limit states. The CBC directs designers to ASCE 7 §2.3 for strength combinations (CBC § 1605.1) .
  • Allowable‑stress combinations: you may use the allowable‑stress combinations in ASCE 7 §2.4, or you may use the CBC’s alternative allowable‑stress combinations in CBC § 1605.2. CBC § 1605.1 explicitly allows either ASCE 7 §2.4 or the alternative CBC combinations (§ 1605.2) .
  • When you use the CBC’s alternative ASD combos (§ 1605.2), follow the alternative forms and the additional rules recorded in that section (including special rules for wind/seismic cases and foundation proportioning) .

Key procedural rules (decision‑relevant items)

  • If you choose ASCE 7 strength combinations, follow ASCE 7 §2.3; the CBC defers to ASCE 7 (CBC § 1605.1) .
  • When using the ASCE 7 allowable‑stress combinations (ASCE 7 §2.4), CBC § 1605.1 lists specific limits/exceptions (for example, treatment of small roof snow and roof live loads with seismic; crane hook load combination limits) — see Exceptions & special cases below for those concrete thresholds .
  • If you use CBC § 1605.2 alternative ASD combinations: (a) allowable stresses may be increased or load combinations reduced where permitted by the material chapters or referenced standards; (b) for wind with counteracting dead load use only two‑thirds of the minimum dead likely to be in place during the wind event; (c) when evaluating sliding/overturning/bearing with these alternative combinations, do not apply the ASCE 7 foundation‑overturning reduction in Section 12.13.4; (d) for foundations proportioned with seismic loads, the vertical seismic effect Ev in ASCE 7 Equation 12.4‑4 may be taken equal to zero — all are stated in § 1605.2 .
  • For CBC § 1605.2 the code also requires each alternative load combination be investigated with one or more variable loads set to zero (to catch omitted coincident effects) .

Decision table (quick reference)

Decision / value What to use or check Code reference
Design philosophy (strength vs. ASD) Strength: ASCE 7 §2.3. ASD: ASCE 7 §2.4 or CBC alternative §1605.2 CBC § 1605.1
Alternative ASD basic combos Use the combinations and rules given in CBC § 1605.2 (examples include D+L+(Lr or 0.7S or R), D+L+0.6W, etc.) CBC § 1605.2
Dead load when counteracting wind in CBC §1605.2 Use 2/3 of minimum dead likely in place during the design wind event when combining dead and wind where they counteract CBC § 1605.2
Roof snow / roof live vs seismic (ASCE 7 §2.4 ASD) If flat roof snow ≤45 psf and roof live ≤30 psf, need not be combined with seismic; if snow >45 psf, combine 15% with seismic (per CBC exception) CBC § 1605.1 (Exceptions)
Crane hook loads with ASD (ASCE 7 §2.4) Crane hook loads need not be combined with roof live, or with >¾ of snow, or >½ of wind when ASCE 7 §2.4 ASD is used (CBC exception) CBC § 1605.1 (Exceptions)
Investigation practice Each combination that’s used to check a member/element shall be evaluated with one or more variable loads set to zero (CBC §1605.2 requirement) CBC § 1605.2

Notes on symbols and referenced definitions

CBC § 1605 refers designers to ASCE 7 for the notation and definitions used in the ASCE combinations (for example D, L, Lr, S, W, R, earthquake effects, etc.). The CBC text references ASCE 7 §2.3 and §2.4 as the authoritative statements of the full numeric factors for strength and ASCE ASD combinations; the CBC’s § 1605.2 provides alternate ASD forms and accompanying modifiers. Verify symbol meanings in ASCE 7 before applying formulae .

Exceptions & special cases

  • ASCE 7 Chapter 18/19 modifications. CBC § 1605.1 allows the ASCE 7 Chapter 18 and 19 modifications to the load combinations to apply where they are required by ASCE 7 (for example special provisions for certain occupancies and systems) .
  • Flat roof snow and roof live combined with seismic (ASD per ASCE 7 §2.4): if flat roof snow ≤ 45 psf and roof live ≤ 30 psf, those loads need not be combined with seismic; if flat roof snow > 45 psf then combine 15% of the snow with seismic — CBC § 1605.1 exception .
  • Crane hook load combinations: when using ASCE 7 §2.4 allowable‑stress combinations, crane hook loads need not be combined with roof live loads, or with more than 3/4 of the snow load, or 1/2 of the wind loads (CBC § 1605.1 exception) .
  • Tornado: if design for tornado loads governs, the CBC § 1605.2 alternative allowable stress combinations shall not be used when tornado loads are controlling — see CBC § 1605.1 exception .
  • Stability checks: regardless of which combination set you use, for overall stability checks (overturning, sliding, buoyancy) use of the combinations in ASCE 7 §2.3 or §2.4 or CBC § 1605.2 is permitted; when using strength combinations, strength reduction factors applicable to soil resistance must be provided by the registered design professional (CBC § 1605.1.1) .
  • Foundations and soil: CBC provides additional guidance tying foundation design/soil bearing values to the chosen combination set (see CBC § 1605.2 and related sections in the soil chapters) — e.g., CBC notes special foundation proportioning allowances when using the alternative ASD combos (CBC § 1605.2) .

Common mistakes

  • Treating the CBC as prescriptive to only one combination set. CBC permits multiple sets (strength combos from ASCE 7 §2.3, ASD from ASCE 7 §2.4, or CBC § 1605.2) — pick one appropriate to the design approach and follow its rules; do not mix factors from different approaches without justification and code authority (CBC § 1605.1) .
  • Forgetting the CBC exceptions. For example, failing to apply the flat‑roof snow/roof live exceptions with seismic when using ASCE 7 §2.4 ASD or ignoring the crane hook combination limits can lead to overly conservative or non‑compliant combinations (CBC § 1605.1 exceptions) .
  • Using full dead load with counteracting wind. When using the CBC alternative ASD combos that include wind, you must use only two‑thirds of the minimum dead load likely to be in place during the wind event where the dead load counteracts wind (CBC § 1605.2) .
  • Not checking "variable loads = zero" cases. CBC § 1605.2 explicitly requires investigating each alternative ASD combination with one or more variable loads set to zero to ensure no unanticipated governing condition is missed .
  • Applying CBC § 1605.2 when tornado loads govern. The code forbids using the alternative ASD combinations of § 1605.2 when tornado loads are the controlling design action (CBC § 1605.1 exception) .

Worked example — concrete scenario using CBC § 1605.2 alternative ASD combination

Situation: a short cantilevered bracket supports a small roof‑mounted device. You choose the CBC alternative allowable‑stress combinations (CBC § 1605.2) for member checks. The element has:

  • Dead load D = 1,000 lb
  • Live load L = 500 lb
  • Wind load W = 800 lb (For simplicity, assume no snow, roof live Lr, rain R, or other variables govern in this example.)

CBC § 1605.2 lists, among others, the alternative ASD combination D + L + 0.6W (Equation 16A‑2) for cases including wind effects .

Apply Equation 16A‑2:

  1. Start with D + L + 0.6W (CBC Equation 16A‑2) .
  2. Insert numbers: 1,000 + 500 + 0.6 × 800 = 1,000 + 500 + 480 = 1,980 lb.
  3. Conclusion: design the bracket for 1,980 lb (allowable‑stress combination load) for the wind‑involving case. Also evaluate the other CBC § 1605.2 combinations (e.g., D + L + (Lr or 0.7 S or R) and combinations with both wind and snow per the CBC equations) and verify each with one or more variable loads set to zero as required by CBC § 1605.2 .

Notes:

  • If instead you had used ASCE 7 strength (LRFD) combinations, you must use ASCE 7 §2.3 factors — CBC § 1605.1 requires using ASCE 7 §2.3 for strength design but the ASCE 7 text itself is not reproduced in the CBC. Refer to ASCE 7 for the numeric LRFD factors and combinations (CBC § 1605.1) .
  • If the element were supporting roof snow >45 psf and you were using ASCE 7 §2.4 ASD, recall the CBC exception: 15% of snow must be combined with seismic in that threshold case (CBC § 1605.1 exception) .

Related provisions (select CBC sections)

  • § 1605 — Load combinations (general authority and options)
  • § 1605.1 — General; ASCE 7 references; exceptions (flat roof snow/roof live thresholds, crane hook limits, tornado rule, stability allowance)
  • § 1605.2 — Alternative allowable‑stress design load combinations and special rules (dead load reduction for wind, foundation proportioning notes, required zeroed variable investigations)
  • § 1605.1.1 — Stability: use of allowed combinations for overturning/sliding/buoyancy checks; soil resistance reduction factor requirements for strength design
  • Chapter references: ASCE 7 (as adopted by CBC references) — ASCE 7 §2.3 (strength) and §2.4 (ASD) per CBC § 1605.1; consult ASCE 7 for the full set of numeric factors (ASCE 7 text is referenced, not reproduced, in the CBC)

Code references

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

  • CBC § 1605.1 High relevance — show source text

    SECTION 1605—LOAD COMBINATIONS

    1605.1 General. Buildings and other structures and portions thereof shall be designed to resist the strength load combinations specified in ASCE 7, Section 2.3, the allowable stress design load combinations specified in ASCE 7, Section 2.4, or the alternative allowable stress design load combinations of Section 1605.2.

    Exceptions:

    1. The modifications to load combinations of ASCE 7, Section 2.3, ASCE 7, Section 2.4 and Section 1605.2 specified in ASCE 7 Chapters 18 and 19 shall apply.

    16-8 2025 CALIFORNIA BUILDING CODE

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

    STRUCTURAL DESIGN

    1. Where the allowable stress design load combinations of ASCE 7, Section 2.4 are used, flat roof snow loads of 45 pounds per square foot (2.15 kN/m [2] ) and roof live loads of 30 pounds per square foot (1.44 kN/m [2] ) or less need not be combined with seismic load. Where flat roof snow loads exceed 45 pounds per square foot (2.15 kN/m [2] ), 15 percent shall be combined with seismic loads.

    2. Where the allowable stress design load combinations of ASCE 7 Section 2.4 are used, crane hook loads need not be combined with roof live loads or with more than three-fourths of the snow load or one-half of the wind loads.

    3. Where design for tornado loads is required, the alternative allowable stress design load combinations of Section 1605.2 shall not apply when tornado loads govern the design.

    1605.1.1 Stability. Regardless of which load combinations are used to design for strength, where overall structure stability (such as stability against overturning, sliding, or buoyancy) is being verified, use of the load combinations specified in Section 2.3 or 2.4 of ASCE 7, and in Section 1605.2 shall be permitted. Where the load combinations specified in ASCE 7, Section 2.3 are used, strength reduction factors applicable to soil resistance shall be provided by a registered design professional. The stability of retaining walls shall be verified in accordance with Section 1807.2.3.

    1605.2 Alternative allowable stress design load combinations. In lieu of the load combinations in ASCE 7, Section 2.4, structures and portions thereof shall be permitted to be designed for the most critical effects resulting from the following combinations. Where using these alternative allowable stress load combinations that include wind or seismic loads, allowable stresses are permitted to be increased or load combinations reduced where permitted by the material chapter of this code or the referenced standards. For load combinations that include the counteracting effects of dead and wind loads, only two-thirds of the minimum dead load likely to be in place during a design wind event shall be used. Where using these alternative load combinations to evaluate sliding, overturning and soil bearing at the soil-structure interface, the reduction of foundation overturning from Section 12.13.4 in ASCE 7 shall not be used. Where using these alternative basic load combinations for proportioning foundations for loadings, which include seismic loads, the vertical seismic load effect, E v, in Equation 12.4-4 of ASCE 7 is permitted to be taken equal to zero.

  • CBC § 16-3 High relevance — show source text

    1601 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-3

    1602 Notations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-3

    1603 Construction Documents . . . . . . . . . . . . . . . . . . . . . . . 16-4

    1604 General Design Requirements. . . . . . . . . . . . . . . . . . . 16-5

    1605 Load Combinations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-8

    1606 Dead Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-9

    1607 Live Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16-10

    1608 Snow Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16-18

    1609 Wind Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16-24

    1610 Soil Loads and Hydrostatic Pressure. . . . . . . . . . . .16-31

    1611 Rain Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16-32

    1612 Flood Loads. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16-33

    1613 Earthquake Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . .16-34

    1614 Atmospheric Ice Loads . . . . . . . . . . . . . . . . . . . . . . . .16-36

    1615 Tsunami Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16-36

    1616 Structural Integrity . . . . . . . . . . . . . . . . . . . . . . . . . . .16-36

    1617 Additional Requirements for Community Colleges [DSA-SS/CC] . . . . . . . . . . . . . 16-38

    CHAPTER 16A STRUCTURAL DESIGN. . . . . . . . . . . . . . . . . 16A-1

    1601A General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16A-3

    1602A Notations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16A-3

  • CBC § 4.09 High relevance — show source text

    For anchorage of concrete or masonry walls to roof and floor diaphragms, the out-of-plane strength design force shall not be less than 280 lb/linear ft (4.09 kN/m) of wall. Required anchors in masonry walls of hollow units or cavity walls shall be embedded in a reinforced grouted structural element of the wall. See Sections 1609 for wind design requirements and 1613 A for earthquake design requirements. 1604 A .8.3 Decks. Where supported by attachment to an exterior wall, decks shall be positively anchored to the primary structure and designed for both vertical and lateral loads as applicable. Such attachment shall not be accomplished by the use of toenails or nails subject to withdrawal. Where positive connection to the primary building structure cannot be verified during inspection, decks shall be self-supporting. Connections of decks with cantilevered framing members to exterior walls or other framing members shall be designed for both of the following:

    1. The reactions resulting from the dead load and live load specified in Table 1607 A .1, or the snow load specified in Section 1608, in accordance with Section 1605 A, acting on all portions of the deck.
    2. The reactions resulting from the dead load and live load specified in Table 1607 A .1, or the snow load specified in Section 1608 A, in accordance with Section 1605 A, acting on the cantilevered portion of the deck, and no live load or snow load on the remaining portion of the deck. 1604 A .9 Wind and seismic detailing. Lateral force-resisting systems shall meet seismic detailing requirements and limitations prescribed in this code and ASCE 7 Chapters 11, 12, 13, 15, 17 and 18 as applicable, even where wind load effects are greater than seismic load effects.

    Exception: References within ASCE 7 to Chapter 14 shall not apply, except as specifically required herein.

    1604 A .10 Loads on storm shelters. Loads and load combinations on storm shelters shall be determined in accordance with ICC 500.

    2025 CALIFORNIA BUILDING CODE 16A-9

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

    �

    STRUCTURAL DESIGN

    SECTION 1605 A —LOAD COMBINATIONS

    1605 A .1 General. Buildings and other structures and portions thereof shall be designed to resist the strength load combinations specified in ASCE 7, Section 2.3, the allowable stress design load combinations specified in ASCE 7, Section 2.4, or the alternative allowable stress design load combinations of Section 1605 A .2. Exceptions:

  • CBC § 2.3 High relevance — show source text

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

    �

    STRUCTURAL DESIGN

    SECTION 1605 A —LOAD COMBINATIONS

    1605 A .1 General. Buildings and other structures and portions thereof shall be designed to resist the strength load combinations specified in ASCE 7, Section 2.3, the allowable stress design load combinations specified in ASCE 7, Section 2.4, or the alternative allowable stress design load combinations of Section 1605 A .2. Exceptions:

    1. The modifications to load combinations of ASCE 7, Section 2.3, ASCE 7, Section 2.4 and Section 1605 A .2 specified in ASCE 7 Chapters 18 and 19 shall apply.

    2. Where the allowable stress design load combinations of ASCE 7, Section 2.4 are used, flat roof snow loads of 45 pounds per square foot (2.15 kN/m [2] ) and roof live loads of 30 pounds per square foot (1.44 kN/m [2] ) or less need not be combined with seismic load. Where flat roof snow loads exceed 45 pounds per square foot (2.15 kN/m [2] ), 15 percent shall be combined with seismic loads.

    3. Where the allowable stress design load combinations of ASCE 7 Section 2.4 are used, crane hook loads need not be combined with roof live loads or with more than three-fourths of the snow load or one-half of the wind loads.

    4. Where design for tornado loads is required, the alternative allowable stress design load combinations of Section 1605 A .2 shall not apply when tornado loads govern the design.

    1605 A .1.1 Stability. Regardless of which load combinations are used to design for strength, where overall structure stability (such as stability against overturning, sliding, or buoyancy) is being verified, use of the load combinations specified in Section 2.3 or 2.4 of ASCE 7, and in Section 1605 A .2 shall be permitted. Where the load combinations specified in ASCE 7, Section 2.3 are used, strength reduction factors applicable to soil resistance shall be provided by a registered design professional. The stability of retaining walls shall be verified in accordance with Section 1807 A .2.3. When using allowable stress design, factor of safety for soil bearing values shall not be less than the overstrength factor of the structures supported.

    1605A.1.2 Foundation resistance. [OSHPD 1 & 4] Strength design for foundation geotechnical capacity shall be in accordance with ASCE 7, Section 12.13.5 for all strength design load combinations, except that Resistance Factor (Ø) shall be permitted to be 1.0 for load combinations with amplified seismic forces in accordance with Section 1617A.1.15. Allowable stress design for founda- tion geotechnical capacity shall be in accordance with ASCE 7, Section 12.13.6 for all allowable stress design load combinations, and shall be established to be consistent with strength design requirements in ASCE 7, Section 12.13.5.

    1605 A **.2 Alternative allowable stress design load combinations.

  • CBC § 15-20 Medium relevance — show source text

    1508 Roof Insulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15-20

    1509 Roof Coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15-20

    1510 Radiant Barriers Installed Above Deck . . . . . . . . . .15-21

    1511 Rooftop Structures . . . . . . . . . . . . . . . . . . . . . . . . . . .15-21

    1512 Reroofing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15-24

    1513 [DSA-SS & DSA-SS/CC, OSHPD 1, 1R, 2, 4 & 5] Seismic Anchorage of Slate Shingle, Clay and Concrete Tile Roof Coverings. . . . . . . 15-25

    INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . INDEX-1

    HISTORY NOTE TO VOLUME 1 . . . . . . . . . . . . . . . . . . . . . .HIST-1

    VOLUME 2

    CHAPTER 16 STRUCTURAL DESIGN . . . . . . . . . . . . . . . . . .16-1

    1601 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-3

    1602 Notations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-3

    1603 Construction Documents . . . . . . . . . . . . . . . . . . . . . . . 16-4

    1604 General Design Requirements. . . . . . . . . . . . . . . . . . . 16-5

    1605 Load Combinations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-8

    1606 Dead Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-9

    1607 Live Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16-10

    1608 Snow Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16-18

    1609 Wind Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16-24

    1610 Soil Loads and Hydrostatic Pressure. . . . . . . . . . . .16-31

  • CBC § 110.2 Medium relevance — show source text

    Water-to-water heat pumps with a capacity less than 135,000 Btu/h are included in Table 110.2-B, Heat Pumps—Minimum Efficiency Requirements.
    i. Source leaving liquid temperature.
    1. The cooling evaporator liquid flow rate used for the heating rating for a reverse cycle air-to-water heat pump shall be the flow rate determined during the full load cooling rating.
    2. The cooling evaporator liquid flow rate for the simultaneous cooling and heating and heat recovery liquid cooled chilling packages rating shall be the liquid flow rates
    from the cooling operation full-load rating.
    3. For heating-only fluid-to-fluid chiller packages, the evaporator flow rate obtained with an entering liquid temperature of 54°F and a leaving liquid temperature of 44°F
    shall be used.
    j. NA means the requirements are not applicable.|a. The size category is the full-load net refrigeration cooling mode capacity, which is the capacity of the evaporator available for cooling of the thermal load external to the chill-
    ing package.
    b. For air source heat pumps, compliance with both the 47°F and 17°F heating source outdoor air temperature (OAT) rating efficiency is required for heating.
    c. Heating full-load rating conditions are at standard rating conditions defined in AHRI 550/590 (I-P), Table 4, includes the impact of defrost for air source heating ratings.
    d. For units that operate in both cooling and heating, compliance with both the cooling and heating efficiency is required.
    e. For heat recovery heating chilling package applications where there is simultaneous cooling and heating, compliance with the heating performance heat recover COPHR is
    only required at one of the four heating AHRI 550/590 (I-P) standard ratings conditions of Low, Medium, Hot-Water 1 or Hot-Water 2. Compliance with the cooling-only perfor-
    mance is required as defined in Notes b and c of Table 110.2-I.
    f. For applications where the chilling package is installed to operate only in heating, compliance only with the heating performance COPH is required at only one of the heating
    AHRI 550/590 (I-P) standard rating conditions of Low, Medium, High, or Boost. Compliance with cooling performance is not required.
    g. For heat pump chilling package applications where the cooling capacity is not being used for conditioning, compliance with the heating performance COPH is only required at
    one of the heating AHRI 550/590 (I-P) standard rating conditions of Low, Medium, High, or Boost. Compliance with the cooling performance is required as defined in Notes b
    and c of Table 110.2-I, except as noted in Note f.
    h. Water-to-water heat pumps with a capacity less than 135,000 Btu/h are included in Table 110.2-B, Heat Pumps—Minimum Efficiency Requirements.
    i. Source leaving liquid temperature.
    1. The cooling evaporator liquid flow rate used for the heating rating for a reverse cycle air-to-water heat pump shall be the flow rate determined during the full load cooling rating.
    2. The cooling evaporator liquid flow rate for the simultaneous cooling and heating and heat recovery liquid cooled chilling packages rating shall be the liquid flow rates
    from the cooling operation full-load rating.
    3. For heating-only fluid-to-fluid chiller packages, the evaporator flow rate obtained with an entering liquid temperature of 54°F and a leaving liquid temperature of 44°F
    shall be used.
    j. NA means the requirements are not applicable.|a.

  • CBC § 4.93 Medium relevance — show source text

    55|AHRI 550/590| |> 400 and < 600|44i|> 4.93|> 3.96|> 2.97|NAj|AHRI 550/590| |> 400 and < 600|65 i|NAj|NAj|NAj|> 3.9|AHRI 550/590| |> 600|44i|> 4.93|> 3.96|> 2.97|NAj|AHRI 550/590| |> 600|65 i|NAj|NAj|NAj|> 3.9|AHRI 550/590| |a. The size category is the full-load net refrigeration cooling mode capacity, which is the capacity of the evaporator available for cooling of the thermal load external to the chill-
    ing package.
    b. For air source heat pumps, compliance with both the 47°F and 17°F heating source outdoor air temperature (OAT) rating efficiency is required for heating.
    c. Heating full-load rating conditions are at standard rating conditions defined in AHRI 550/590 (I-P), Table 4, includes the impact of defrost for air source heating ratings.
    d. For units that operate in both cooling and heating, compliance with both the cooling and heating efficiency is required.
    e. For heat recovery heating chilling package applications where there is simultaneous cooling and heating, compliance with the heating performance heat recover COPHR is
    only required at one of the four heating AHRI 550/590 (I-P) standard ratings conditions of Low, Medium, Hot-Water 1 or Hot-Water 2. Compliance with the cooling-only perfor-
    mance is required as defined in Notes b and c of Table 110.2-I.
    f. For applications where the chilling package is installed to operate only in heating, compliance only with the heating performance COPH is required at only one of the heating
    AHRI 550/590 (I-P) standard rating conditions of Low, Medium, High, or Boost. Compliance with cooling performance is not required.
    g. For heat pump chilling package applications where the cooling capacity is not being used for conditioning, compliance with the heating performance COPH is only required at
    one of the heating AHRI 550/590 (I-P) standard rating conditions of Low, Medium, High, or Boost. Compliance with the cooling performance is required as defined in Notes b
    and c of Table 110.2-I, except as noted in Note f.
    h. Water-to-water heat pumps with a capacity less than 135,000 Btu/h are included in Table 110.2-B, Heat Pumps—Minimum Efficiency Requirements.
    i. Source leaving liquid temperature.
    1. The cooling evaporator liquid flow rate used for the heating rating for a reverse cycle air-to-water heat pump shall be the flow rate determined during the full load cooling rating.
    2. The cooling evaporator liquid flow rate for the simultaneous cooling and heating and heat recovery liquid cooled chilling packages rating shall be the liquid flow rates
    from the cooling operation full-load rating.
    3. For heating-only fluid-to-fluid chiller packages, the evaporator flow rate obtained with an entering liquid temperature of 54°F and a leaving liquid temperature of 44°F
    shall be used.
    j. NA means the requirements are not applicable.|a. The size category is the full-load net refrigeration cooling mode capacity, which is the capacity of the evaporator available for cooling of the thermal load external to the chill-
    ing package.
    b.

  • CBC § 2109.2.4.9 Medium relevance — show source text

    Adobe 2109.2.4.9

    Fire resistance 704.10 Masonry, wood support 2304.13 Liquefied Petroleum Gas Table 414.5.1,

    415.9.2 Listed (definition) 202 Listing Agency (definition) 202 Live Load 1607

    Construction Documents 1603.1.1

    Posting of 106.1 Roof 1607

    Live/Work Units 310.3, 508.5 Accessibility Chapters 11A and 11B Separation 508.2 Load and Resistance Factor Design (LRFD) 1602.1

    Factored load 1604.2

    Limit state 1604.2

    Load combinations 1605 Wood design 2302.1, 2307 Load Combinations 1605 Allowable stress design 1605, 1605.2 Alternative allowable stress load

    combinations 1605.2 Load and resistance factor design 1605 Strength design 1605 Loads 106, 202 Atmospheric ice 1614 Combinations 1605

    Dead 1606

    Factored load 402.8.2.1, 1604.2,

    1709.2

    Flood 1603.1.7, 1612 Impact 1607.12 Live 508.5.8, 1603.1.1, 1607 Load effects 1604.4

    Nominal load 1604.2 Partial loading 1607.3.1, 1607.3.2 Rain 1603.1.9, 1611 Seismic 1603.1.5, 1613 Snow 1603.1.3, 1608 Soil lateral 1610

    Tornado 1603.1.4, 1609.5, 1609.6.3.2 Tsunami 1615

    Wind 1603.1.4, 1609 Lobbies Assembly occupancy 1030.4 Elevator 405.4.3, 1009.2.1, 1009.4, 3006, 3007.6, 3008.6 Exit discharge 1028.2 Underground buildings 405.4.3 Lobby 202 Local Enforcing Agency 1.8.3 Locks and Latches 1010.2, 1010.2.8 Delayed egress locks 1010.2.12 Electromagnetically locked 1010.2.10 Fire Exit Hardware 1010.2.10, 1010.2.8 Group I-2 407.4.1.1, 1010.2.13 Group I-3 408.4 High-rise 403.5.3 Sensor release 1010.2.11

    Toilet rooms Chapter 29 Lodging Houses 310.4, 310.4.2 Lowest Floor 1603.1.7, 1612.4 Lumber

    General provisions Chapter 23 Quality standards 2303

  • CBC § 16A-9 Medium relevance — show source text
    1. The reactions resulting from the dead load and live load specified in Table 1607 A .1, or the snow load specified in Section 1608 A, in accordance with Section 1605 A, acting on the cantilevered portion of the deck, and no live load or snow load on the remaining portion of the deck. 1604 A .9 Wind and seismic detailing. Lateral force-resisting systems shall meet seismic detailing requirements and limitations prescribed in this code and ASCE 7 Chapters 11, 12, 13, 15, 17 and 18 as applicable, even where wind load effects are greater than seismic load effects.

    Exception: References within ASCE 7 to Chapter 14 shall not apply, except as specifically required herein.

    1604 A .10 Loads on storm shelters. Loads and load combinations on storm shelters shall be determined in accordance with ICC 500.

    2025 CALIFORNIA BUILDING CODE 16A-9

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

    �

    STRUCTURAL DESIGN

    SECTION 1605 A —LOAD COMBINATIONS

    1605 A .1 General. Buildings and other structures and portions thereof shall be designed to resist the strength load combinations specified in ASCE 7, Section 2.3, the allowable stress design load combinations specified in ASCE 7, Section 2.4, or the alternative allowable stress design load combinations of Section 1605 A .2. Exceptions:

    1. The modifications to load combinations of ASCE 7, Section 2.3, ASCE 7, Section 2.4 and Section 1605 A .2 specified in ASCE 7 Chapters 18 and 19 shall apply.

    2. Where the allowable stress design load combinations of ASCE 7, Section 2.4 are used, flat roof snow loads of 45 pounds per square foot (2.15 kN/m [2] ) and roof live loads of 30 pounds per square foot (1.44 kN/m [2] ) or less need not be combined with seismic load. Where flat roof snow loads exceed 45 pounds per square foot (2.15 kN/m [2] ), 15 percent shall be combined with seismic loads.

    3. Where the allowable stress design load combinations of ASCE 7 Section 2.4 are used, crane hook loads need not be combined with roof live loads or with more than three-fourths of the snow load or one-half of the wind loads.

    4. Where design for tornado loads is required, the alternative allowable stress design load combinations of Section 1605 A .2 shall not apply when tornado loads govern the design.

  • CBC § 2306.2 Medium relevance — show source text

    For Case 1 through 6 descriptions see Figure 2306.2(1).|For SI: 1 inch = 25.4 mm, 1 pound per foot = 14.5939 N/m.
    a. For framing of other species: (1) Find specific gravity for species of lumber in ANSI/AWC NDS. (2) For staples find shear value from table for Structural I panels (regardless of
    actual grade) and multiply value by 0.82 for species with specific gravity of 0.42 or greater, or 0.65 for all other species.
    b. Space fasteners maximum 12 inches on center along intermediate framing members (6 inches on center where supports are spaced 48 inches on center).
    c. Framing at adjoining panel edges shall be 3 inches nominal or wider.
    d. Staples shall have a minimum crown width of7/16 inch and shall be installed with their crowns parallel to the long dimension of the framing members.
    e. The minimum nominal width of framing members not located at boundaries or adjoining panel edges shall be 2 inches.
    f. For shear loads of normal or permanent load duration as defined by the ANSI/AWC NDS, the values in the table shall be multiplied by 0.63 or 0.56, respectively.
    g. For Case 1 through 6 descriptions see Figure 2306.2(1).|For SI: 1 inch = 25.4 mm, 1 pound per foot = 14.5939 N/m.
    a. For framing of other species: (1) Find specific gravity for species of lumber in ANSI/AWC NDS. (2) For staples find shear value from table for Structural I panels (regardless of
    actual grade) and multiply value by 0.82 for species with specific gravity of 0.42 or greater, or 0.65 for all other species.
    b. Space fasteners maximum 12 inches on center along intermediate framing members (6 inches on center where supports are spaced 48 inches on center).
    c. Framing at adjoining panel edges shall be 3 inches nominal or wider.
    d. Staples shall have a minimum crown width of7/16 inch and shall be installed with their crowns parallel to the long dimension of the framing members.
    e. The minimum nominal width of framing members not located at boundaries or adjoining panel edges shall be 2 inches.
    f. For shear loads of normal or permanent load duration as defined by the ANSI/AWC NDS, the values in the table shall be multiplied by 0.63 or 0.56, respectively.
    g. For Case 1 through 6 descriptions see Figure 2306.2(1).|For SI: 1 inch = 25.4 mm, 1 pound per foot = 14.5939 N/m.
    a. For framing of other species: (1) Find specific gravity for species of lumber in ANSI/AWC NDS. (2) For staples find shear value from table for Structural I panels (regardless of
    actual grade) and multiply value by 0.82 for species with specific gravity of 0.42 or greater, or 0.65 for all other species.
    b. Space fasteners maximum 12 inches on center along intermediate framing members (6 inches on center where supports are spaced 48 inches on center).
    c. Framing at adjoining panel edges shall be 3 inches nominal or wider.
    d.

  • CBC § 803.13 Medium relevance — show source text

    Incidental uses 509 Interior finishes Table 803.13, 804 Live load Table 1607.1 Means of egress Aisles 1018.3

    Stairway, exit access 1019 Travel distance 1006.3, 1017.2,

    1006.2.1

    Mixed occupancies 508.2, 508.3, 508.4 Accessory 303.1.2, 508.2 Ambulatory care facilities 422 Assembly 303.1.2

    Assembly spaces 1030 Exit signs 1013.1 Guards 1015.2, 1030.17 Main exit 1030.3

    Open air 1005.3.1, 1005.3.2, 1006.3, 1009.6.4, 1019.3, 1027, 1030.6.2 Panic hardware 1010.2.8, 1010.4.1 Smoke-protected 1005.3.1, 1005.3.2, 1006.3, 1009.6.4, 1019.3, 1027, 1030.6.2 Travel distance 1006.2.1, 1006.3, 1017.2, 1030.7 Mixed occupancies 508.3, 508.4 Accessory 508.2 Education 303.1.3

    Live/work units 508.5 Mall buildings 402 Other occupancies 303.1.1, 303.1.2, 303.1.3 Parking below/above 510.7, 510.9 Religious facilities 303.1.4 Special mixed 510.2 Motion picture theaters 409, 507.12 Occupancy exceptions 303.1.1, 303.1.2, 303.1.3, 303.1.4, 305.1.1, 305.2.1 Plumbing fixtures Chapter 29 Risk category Table 1604.5 Seating, fixed (see Seating, Fixed) Seating, open-air assembly seating 1030.6.3 Seating, smoke-protected 1030.6.2 Sprinkler protection 410, 504.3, 506.2, 507.12, 507.4, 507.6, 507.7, 903.2.1 Stages and platforms 410 Standpipes 905.3.2, 905.5.1 Unlimited area 507.12, 507.4, 507.4.1, 507.6, 507.7 Assisted Living (see Group I-1 and Group R-4) 308.2, 310.5, 420 Atmospheric Ice Loads 1614 Atrium 404

    Alarms and detection 404.4, 907.2.15 Enclosure 404.6, 707.3.6 Interior finish 404.8 Means of egress 404.9, 404.10, 404.11, 1006.3.2, 1017.3, 1019.3, 1023.2,

    1028.2

    Smoke control 404.5, 909 Sprinkler protection 404.3 Standby power 404.7 Travel distance 404.9, 1006.2.1, 1006.3, 1017.2

    Use 404.2

    Attic 202

  • CBC § 1604.8.3 Medium relevance — show source text

    See Sections 1609 for wind design requirements and 1613 for earthquake design requirements. 1604.8.3 Decks. Where supported by attachment to an exterior wall, decks shall be positively anchored to the primary structure and designed for both vertical and lateral loads as applicable. Such attachment shall not be accomplished by the use of toenails or nails subject to withdrawal. Where positive connection to the primary building structure cannot be verified during inspection, decks shall be self-supporting. Connections of decks with cantilevered framing members to exterior walls or other framing members shall be designed for both of the following:

    1. The reactions resulting from the dead load and live load specified in Table 1607.1, or the snow load specified in Section 1608, in accordance with Section 1605, acting on all portions of the deck.
    2. The reactions resulting from the dead load and live load specified in Table 1607.1, or the snow load specified in Section 1608, in accordance with Section 1605, acting on the cantilevered portion of the deck, and no live load or snow load on the remaining portion of the deck. 1604.9 Wind and seismic detailing. Lateral force-resisting systems shall meet seismic detailing requirements and limitations prescribed in this code and ASCE 7 Chapters 11, 12, 13, 15, 17 and 18 as applicable, even where wind load effects are greater than seismic load effects.

    Exception: References within ASCE 7 to Chapter 14 shall not apply, except as specifically required herein.

    1604.10 Loads on storm shelters. Loads and load combinations on storm shelters shall be determined in accordance with ICC 500.

    SECTION 1605—LOAD COMBINATIONS

    1605.1 General. Buildings and other structures and portions thereof shall be designed to resist the strength load combinations specified in ASCE 7, Section 2.3, the allowable stress design load combinations specified in ASCE 7, Section 2.4, or the alternative allowable stress design load combinations of Section 1605.2.

    Exceptions:

    1. The modifications to load combinations of ASCE 7, Section 2.3, ASCE 7, Section 2.4 and Section 1605.2 specified in ASCE 7 Chapters 18 and 19 shall apply.

    16-8 2025 CALIFORNIA BUILDING CODE

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

    STRUCTURAL DESIGN

    1. Where the allowable stress design load combinations of ASCE 7, Section 2.4 are used, flat roof snow loads of 45 pounds per square foot (2.15 kN/m [2] ) and roof live loads of 30 pounds per square foot (1.44 kN/m [2] ) or less need not be combined with seismic load. Where flat roof snow loads exceed 45 pounds per square foot (2.15 kN/m [2] ), 15 percent shall be combined with seismic loads.

    2. Where the allowable stress design load combinations of ASCE 7 Section 2.4 are used, crane hook loads need not be combined with roof live loads or with more than three-fourths of the snow load or one-half of the wind loads.

    3. Where design for tornado loads is required, the alternative allowable stress design load combinations of Section 1605.2 shall not apply when tornado loads govern the design.

Frequently asked questions

Which combination set should I pick: ASCE 7 strength, ASCE 7 ASD, or CBC § 1605.2?

Pick the set that matches your design method: use ASCE 7 §2.3 when designing to strength (limit states); ASCE 7 §2.4 or CBC § 1605.2 when using allowable‑stress. CBC § 1605.1 permits any of these but follow the specific exceptions and modifiers the CBC lists .

If I use CBC § 1605.2, do I still need to check ASCE 7 combinations?

CBC § 1605.2 provides permitted alternative ASD combinations for allowable‑stress design; you must still consider the ASCE 7 strength combinations when designing for strength limit states. Also, the CBC requires you to investigate each CBC § 1605.2 combination with variable loads set to zero to ensure no missed governing case .

How do I treat dead load with wind under CBC § 1605.2?

Where dead and wind counteract, CBC § 1605.2 requires using only two‑thirds of the minimum dead load likely to be in place during the design wind event when combining dead and wind counteracting effects .

Do the CBC § 1605.2 combinations apply when tornado loads govern?

No. The CBC explicitly states the alternative allowable‑stress combinations of § 1605.2 shall not be used when tornado loads govern the design (CBC § 1605.1 exception) .

Must I combine roof snow with seismic?

Under ASCE 7 §2.4 ASD as adopted by CBC § 1605.1, flat roof snow ≤45 psf and roof live ≤30 psf need not be combined with seismic; if flat roof snow >45 psf then combine 15% of the snow with seismic per the CBC exception .

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