Title 24 · California Energy Code

Vented cladding, moisture control and permitted continuous insulation conditions

If you install a Class I or II responsive vapor retarder with exterior continuous foam insulation, the exterior insulation must meet the R‑values listed in Table 1404.3(4) for your climate zone and stud depth to control moisture (this permits use of low‑permeance retarders but does not replace energy‑code insulation requirements).

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Last reviewed: July 6, 2026

What the code requires — plain English

The California Building Code requires that when a Class I or II responsive vapor retarder is used with exterior continuous insulation on framed walls, the continuous insulation must meet the minimum R‑values listed in Table 1404.3(4) (part of § 1404.3). These R‑value minimums vary by climate zone and by whether the wall is framed for 2 × 4 or 2 × 6 studs. § 1404.3 also makes clear these R‑values are intended to control moisture so that Class I/II vapor retarders may be used; they do not replace the California Energy Code thermal requirements.

The single most important rule: if you put a Class I or II responsive vapor retarder in a framed wall with exterior foam continuous insulation, the exterior continuous insulation must meet the R‑value minimum in Table 1404.3(4) for your climate zone and stud depth (see § 1404.3).

Requirements in detail

Key defined terms (first mention bolded)

  • Vented cladding — examples include vinyl lap siding, polypropylene, horizontal aluminum siding, brick veneer with an airspace, rainscreen systems, and other approved vented claddings as listed elsewhere in the code (see Table 1404.3(3) notes).
  • Class I or II responsive vapor retarder — a vapor control material with low permeance installed as a responsive retarder in assemblies per the vapor retarder tables and notes in § 1404.3.
  • Continuous insulation — insulation applied to the exterior face of the wall framing (foam plastic insulating sheathing or insulated siding used as exterior continuous insulation per the table).

Minimum continuous‑insulation R‑values that permit Class I/II responsive vapor retarders

Climate zone Stud framing Minimum exterior continuous insulation required (R‑value) Code reference
3 (typical framed wall) R‑2 Table 1404.3(4) — § 1404.3.
4, 5, 6 2 × 4 wall R‑3 Table 1404.3(4) — § 1404.3.
4, 5, 6 2 × 6 wall R‑5 Table 1404.3(4) — § 1404.3.
7 2 × 4 wall R‑5 Table 1404.3(4) — § 1404.3.
7 2 × 6 wall R‑7.5 Table 1404.3(4) — § 1404.3.
8 2 × 4 wall R‑7.5 Table 1404.3(4) — § 1404.3.
8 2 × 6 wall R‑10 Table 1404.3(4) — § 1404.3.

Notes under the table: the table’s values apply only to insulation used to control moisture so that Class I or II vapor retarders may be used; they do not supersede energy‑code thermal envelope requirements.

Spray‑foam and alternate compliance (moisture control)

  • Spray polyurethane foam (applied to the interior side of sheathing, OSB, fiberboard, gypsum, etc.) with an installed permeance ≤ 1.5 perms can be used to meet the continuous‑insulation moisture‑control requirement if either: (1) the spray foam R‑value alone meets the Table 1404.3(4) R‑value, or (2) the combined R‑value of the spray foam plus exterior continuous insulation equals or exceeds the Table value. See § 1404.3.1 for details.

Vapor retarder installation and air‑barrier interaction

  • Vapor retarders must be installed per the manufacturer’s instructions or an approved design; where a vapor retarder functions as part of the continuous air barrier, it must be installed to satisfy the energy‑code air‑barrier requirements as well (see § 1404.3.2).

Climate zone mapping / interpretation

  • The section uses IECC climate zones; mapping between the IECC zones used here and California Energy Code zones is handled in the code (see § 1404.3.3). Use the code’s climate‑zone mapping when determining which line in Table 1404.3(4) applies.

Exceptions & special cases

  • The R‑value columns in Table 1404.3(4) apply only when the insulation is being used for moisture control to permit Class I/II vapor retarders; they do not alter mandatory thermal‑performance requirements in the California Energy Code (Table note a).
  • When using spray foam per § 1404.3.1, check the installed permeance and either meet the Table R‑value with spray foam alone or use the combined R‑value approach described in that section.
  • If a wall assembly uses a Class I vapor retarder on both exterior and interior and the interior one is not a responsive retarder, an approved hygrothermal design is required (see the vapor retarder options and notes in § 1404.3 / Table 1404.3(2)).

Common mistakes

  • Treating the Table R‑values as the same as the energy‑code required R‑values — the Table values are only to permit Class I/II vapor retarders for moisture control and do not replace the California Energy Code envelope requirements.
  • Forgetting the stud depth distinction (2 × 4 vs 2 × 6). The required exterior continuous R differs by stud depth in many climate zones — check the correct row in Table 1404.3(4).
  • Using unapproved claddings as “vented cladding.” Only the claddings and systems listed as examples (vinyl lap, horizontal aluminum, rainscreens, brick veneer with specified airspace, etc.) qualify without additional approval — see the vented‑cladding examples in the code (Table 1404.3(3) notes).
  • Assuming any foam exterior insulation automatically counts as a Class I/II vapor retarder — the foam must be a Class I or II vapor retarder at the installed thickness or have an appropriate facer, or meet spray‑foam provisions in § 1404.3.1.
  • Neglecting proper vapor‑retarder installation and air‑barrier continuity; vapor retarders used as part of the air barrier must be installed to meet air‑barrier requirements per § 1404.3.2.

Worked example — climate zone 5, framed with 2 × 6 studs

Scenario: new wood‑frame exterior wall in Climate Zone 5, with a Class II responsive vapor retarder on the interior and exterior foam insulating sheathing as continuous insulation on the outside of the sheathing.

  1. Look up the required R‑value in Table 1404.3(4) (part of § 1404.3): for Climate Zones 4, 5, 6 the table requires R‑3 over a 2 × 4 wall and R‑5 over a 2 × 6 wall. Since the wall is 2 × 6, the exterior continuous insulation must provide at least R‑5.

  2. Confirm the intent: these R‑values are required only to control moisture so the Class II vapor retarder is permitted; you still must meet the California Energy Code thermal envelope requirements separately.

  3. If instead you plan to use interior spray foam (applied to the interior of the sheathing) with permeance ≤ 1.5 perms, you may comply if the spray foam R equals or exceeds R‑5, or if the spray foam R plus the exterior continuous insulation R together equal or exceed R‑5 (see § 1404.3.1). For example, 1.5" of closed‑cell spray foam (~R‑7 to R‑8 depending on product) would by itself exceed R‑5 and meet the moisture‑control requirement; verify manufacturer R and permeance.

Related provisions (code sections)

  • § 1404.3 — Vapor retarder options and Tables 1404.3(2), 1404.3(3) and Table 1404.3(4) (continuous insulation with Class I or II responsive vapor retarder).
  • § 1404.3.1 — Spray foam plastic insulation provisions for moisture control (permeance ≤ 1.5 perms and combined‑R options).
  • § 1404.3.2 — Vapor retarder installation (manufacturer instructions, air‑barrier interaction).
  • § 1404.3.3 — Climate‑zone mapping notes used by this section.
  • § 1404.4 — Flashing and drainage details to prevent moisture entry into the exterior wall.

Code references

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

  • § 1404.3 High relevance — show source text

    Where a Class I or II vapor retarder is used in combination with foam plastic insulating sheathing installed as continuous insulation on the exterior side of frame walls, the
    continuous insulation shall comply with Table 1404.3(4) and the Class I or II vapor retarder shall be a responsive vapor retarder.|a. A responsive vapor retarder shall be allowed on the interior side of any frame wall in all climate zones.
    b. In frame walls with a Class I vapor retarder on the exterior side, use of a Class I interior vapor retarder that is not a responsive vapor retarder shall require an_approved_ design.
    c. Where a Class I or II vapor retarder is used in combination with foam plastic insulating sheathing installed as continuous insulation on the exterior side of frame walls, the
    continuous insulation shall comply with Table 1404.3(4) and the Class I or II vapor retarder shall be a responsive vapor retarder.|a. A responsive vapor retarder shall be allowed on the interior side of any frame wall in all climate zones.
    b. In frame walls with a Class I vapor retarder on the exterior side, use of a Class I interior vapor retarder that is not a responsive vapor retarder shall require an_approved_ design.
    c. Where a Class I or II vapor retarder is used in combination with foam plastic insulating sheathing installed as continuous insulation on the exterior side of frame walls, the
    continuous insulation shall comply with Table 1404.3(4) and the Class I or II vapor retarder shall be a responsive vapor retarder.|

    TABLE 1404.3(3)—CLASS III VAPOR RETARDERS Col2
    ZONE CLASS III VAPOR RETARDERS PERMITTED FOR:a, b
    4 Vented cladding over wood structural panels
    Vented cladding over fiberboard
    Vented cladding over gypsum
    Continuous insulation with_R_-value ≥ R-2.5 over 2 × 4 wall
    Continuous insulation with_R_-value ≥ R-3.75 over 2 × 6 wall
    5 Vented cladding over wood structural panels
    Vented cladding over fiberboard
    Vented cladding over gypsum
    Continuous insulation with_R_-value ≥ R-5 over 2 × 4 wall
    Continuous insulation with_R_-value ≥ R-7.5 over 2 × 6 wall
    6 Vented cladding over fiberboard
    Vented cladding over gypsum
    Continuous insulation with_R_-value ≥ R-7.5 over 2 × 4 wall
    Continuous insulation with_R_-value ≥ R-11.25 over 2 × 6 wall
    7 Continuous insulation with_R_-value ≥ R-10 over 2 × 4 wall
    Continuous insulation with_R_-value ≥ R-15 over 2 × 6 wall
    8 Continuous insulation with_R_-value ≥ R-12.5 over 2 × 4 wall
    Continuous insulation with_R_-value ≥ R-20 over 2 × 6 wall
    a. Vented cladding shall include vinyl lap siding, polypropylene, horizontal aluminum siding, brick veneer with airspace as specified in this code, rainscreen systems and other
    approved vented claddings.
    b. The requirements in this table apply only to insulation used to control moisture in order to permit the use of Class III vapor retarders. The insulation materials used to satisfy
    this option also contribute to but do not supersede the building thermal envelope requirements of the_California Energy Code_.    		 a.
  • § 14-7 High relevance — show source text

    Vented cladding shall include vinyl lap siding, polypropylene, horizontal aluminum siding, brick veneer with airspace as specified in this code, rainscreen systems and other
    approved vented claddings.
    b. The requirements in this table apply only to insulation used to control moisture in order to permit the use of Class III vapor retarders. The insulation materials used to satisfy
    this option also contribute to but do not supersede the building thermal envelope requirements of the_California Energy Code_.|

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    TABLE 1404.3(4)—CONTINUOUS INSULATION WITH A CLASS I OR II RESPONSIVE VAPOR RETARDER Col2
    CLIMATE ZONE PERMITTED CONDITIONSa
    3 Continuous insulation with_R_-value ≥ R-2
    4, 5, 6 Continuous insulation with_R_-value ≥ R-3 over 2 × 4 wall
    Continuous insulation with_R_-value ≥ R-5 over 2 × 6 wall
    7 Continuous insulation with_R_-value ≥ R-5 over 2 × 4 wall
    Continuous insulation with_R_-value ≥ R-7.5 over 2 × 6 wall
    8 Continuous insulation with_R_-value ≥ R-7.5 over 2 × 4 wall
    Continuous insulation with_R_-value ≥ R-10 over 2 × 6 wall
    a. The requirements in this table apply only to insulation used to control moisture in order to permit the use of Class I or II vapor retarders. The insulation materials used to
    satisfy this option also contribute to but do not supersede the building thermal envelope requirements of the_California Energy Code_.    		 a. The requirements in this table apply only to insulation used to control moisture in order to permit the use of Class I or II vapor retarders. The insulation materials used to
    satisfy this option also contribute to but do not supersede the building thermal envelope requirements of the_California Energy Code_.
    TABLE 1404.3(5)—CONTINUOUS INSULATION ON WALLS WITHOUT A CLASS I, II, OR III INTERIOR VAPOR RETARDERa Col2
    CLIMATE ZONE PERMITTED CONDITIONSb,c
    4 Continuous insulation with_R_-value ≥ 4.5
    5 Continuous insulation with_R_-value ≥ 6.5
    6 Continuous insulation with_R_-value ≥ 8.5
    7 Continuous insulation with_R_-value ≥ 11.5
    8 Continuous insulation with_R_-value ≥ 14
    a. The total insulating value of materials to the interior side of the exterior continuous insulation, including any cavity insulation, shall not exceed R-5. Where the_R_-value of
    materials to the interior side of the exterior continuous insulation exceeds R-5, an_approved_ design shall be required.
    b. A water vapor control material layer having a permeance of not greater than 1 perm in accordance with ASTM E96, Procedure A (dry cup) shall be placed on the exterior side
    of the wall and to the interior side of the exterior continuous insulation. The exterior continuous insulation shall be permitted to serve as the vapor control layer where, at its
    installed thickness or with a facer on its interior face, the exterior continuous insulation is a Class I or II vapor retarder.
    c.
  • § 2.5 High relevance — show source text

    b**| |4|Vented cladding over wood structural panels
    Vented cladding over fiberboard
    Vented cladding over gypsum
    Continuous insulation with_R_-value ≥ R-2.5 over 2 × 4 wall
    Continuous insulation with_R_-value ≥ R-3.75 over 2 × 6 wall| |5|Vented cladding over wood structural panels
    Vented cladding over fiberboard
    Vented cladding over gypsum
    Continuous insulation with_R_-value ≥ R-5 over 2 × 4 wall
    Continuous insulation with_R_-value ≥ R-7.5 over 2 × 6 wall| |6|Vented cladding over fiberboard
    Vented cladding over gypsum
    Continuous insulation with_R_-value ≥ R-7.5 over 2 × 4 wall
    Continuous insulation with_R_-value ≥ R-11.25 over 2 × 6 wall| |7|Continuous insulation with_R_-value ≥ R-10 over 2 × 4 wall
    Continuous insulation with_R_-value ≥ R-15 over 2 × 6 wall| |8|Continuous insulation with_R_-value ≥ R-12.5 over 2 × 4 wall
    Continuous insulation with_R_-value ≥ R-20 over 2 × 6 wall| |a. Vented cladding shall include vinyl lap siding, polypropylene, horizontal aluminum siding, brick veneer with airspace as specified in this code, rainscreen systems and other
    approved vented claddings.
    b. The requirements in this table apply only to insulation used to control moisture in order to permit the use of Class III vapor retarders. The insulation materials used to satisfy
    this option also contribute to but do not supersede the building thermal envelope requirements of the_California Energy Code_.|a. Vented cladding shall include vinyl lap siding, polypropylene, horizontal aluminum siding, brick veneer with airspace as specified in this code, rainscreen systems and other
    approved vented claddings.
    b. The requirements in this table apply only to insulation used to control moisture in order to permit the use of Class III vapor retarders. The insulation materials used to satisfy
    this option also contribute to but do not supersede the building thermal envelope requirements of the_California Energy Code_.|

    2025 CALIFORNIA BUILDING CODE 14-7

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    TABLE 1404.3(4)—CONTINUOUS INSULATION WITH A CLASS I OR II RESPONSIVE VAPOR RETARDER Col2
    CLIMATE ZONE PERMITTED CONDITIONSa
    3 Continuous insulation with_R_-value ≥ R-2
    4, 5, 6 Continuous insulation with_R_-value ≥ R-3 over 2 × 4 wall
    Continuous insulation with_R_-value ≥ R-5 over 2 × 6 wall
    7 Continuous insulation with_R_-value ≥ R-5 over 2 × 4 wall
    Continuous insulation with_R_-value ≥ R-7.5 over 2 × 6 wall
    8 Continuous insulation with_R_-value ≥ R-7.5 over 2 × 4 wall
    Continuous insulation with_R_-value ≥ R-10 over 2 × 6 wall
    a. The requirements in this table apply only to insulation used to control moisture in order to permit the use of Class I or II vapor retarders.
  • § 1404.3.1 High relevance — show source text

    The exterior continuous insulation shall be permitted to serve as the vapor control layer where, at its
    installed thickness or with a facer on its interior face, the exterior continuous insulation is a Class I or II vapor retarder.
    c. The requirements of this table apply only to continuous insulation used to control moisture in order to allow walls without a Class I, II or III interior vapor retarder. The insula-
    tion materials used to satisfy this option also contribute to but do not supersede the_building_ thermal envelope requirements of the_California Energy Code_.|a. The total insulating value of materials to the interior side of the exterior continuous insulation, including any cavity insulation, shall not exceed R-5. Where the_R_-value of
    materials to the interior side of the exterior continuous insulation exceeds R-5, an_approved_ design shall be required.
    b. A water vapor control material layer having a permeance of not greater than 1 perm in accordance with ASTM E96, Procedure A (dry cup) shall be placed on the exterior side
    of the wall and to the interior side of the exterior continuous insulation. The exterior continuous insulation shall be permitted to serve as the vapor control layer where, at its
    installed thickness or with a facer on its interior face, the exterior continuous insulation is a Class I or II vapor retarder.
    c. The requirements of this table apply only to continuous insulation used to control moisture in order to allow walls without a Class I, II or III interior vapor retarder. The insula-
    tion materials used to satisfy this option also contribute to but do not supersede the_building_ thermal envelope requirements of the_California Energy Code_.|

    �

    EXTERIOR WALLS

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

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

    1404.3.2 Vapor retarder installation. Vapor retarders shall be installed in accordance with the manufacturer’s instructions or an approved design. Where a vapor retarder also functions as a component of a continuous air barrier, the vapor retarder shall be installed as an air barrier in accordance with the California Energy Code . 1404.3.3 California Energy Code and International Energy Conservation Code Climate Zones. The IECC climate zones used by this section differ from those used by the California Energy Code to determine applicability of energy efficiency measures. Comparison of IECC and California Energy Code climate zones is shown in Chapter 12, Table 1202.3.1. 1404.4 Flashing. Flashing shall be installed in such a manner so as to prevent moisture from entering the exterior wall or to redirect that moisture to the surface of the exterior wall covering or to a water-resistive barrier complying with Section 1403.2 and that is part of a means of drainage complying with Section 1402.2.

  • § 1404.3 High relevance — show source text

    The requirements in this table apply only to insulation used to control moisture in order to permit the use of Class I or II vapor retarders. The insulation materials used to
    satisfy this option also contribute to but do not supersede the building thermal envelope requirements of the_California Energy Code_.|

    TABLE 1404.3(5)—CONTINUOUS INSULATION ON WALLS WITHOUT A CLASS I, II, OR III INTERIOR VAPOR RETARDERa Col2
    CLIMATE ZONE PERMITTED CONDITIONSb,c
    4 Continuous insulation with_R_-value ≥ 4.5
    5 Continuous insulation with_R_-value ≥ 6.5
    6 Continuous insulation with_R_-value ≥ 8.5
    7 Continuous insulation with_R_-value ≥ 11.5
    8 Continuous insulation with_R_-value ≥ 14
    a. The total insulating value of materials to the interior side of the exterior continuous insulation, including any cavity insulation, shall not exceed R-5. Where the_R_-value of
    materials to the interior side of the exterior continuous insulation exceeds R-5, an_approved_ design shall be required.
    b. A water vapor control material layer having a permeance of not greater than 1 perm in accordance with ASTM E96, Procedure A (dry cup) shall be placed on the exterior side
    of the wall and to the interior side of the exterior continuous insulation. The exterior continuous insulation shall be permitted to serve as the vapor control layer where, at its
    installed thickness or with a facer on its interior face, the exterior continuous insulation is a Class I or II vapor retarder.
    c. The requirements of this table apply only to continuous insulation used to control moisture in order to allow walls without a Class I, II or III interior vapor retarder. The insula-
    tion materials used to satisfy this option also contribute to but do not supersede the_building_ thermal envelope requirements of the_California Energy Code_.    		 a. The total insulating value of materials to the interior side of the exterior continuous insulation, including any cavity insulation, shall not exceed R-5. Where the_R_-value of
    materials to the interior side of the exterior continuous insulation exceeds R-5, an_approved_ design shall be required.
    b. A water vapor control material layer having a permeance of not greater than 1 perm in accordance with ASTM E96, Procedure A (dry cup) shall be placed on the exterior side
    of the wall and to the interior side of the exterior continuous insulation. The exterior continuous insulation shall be permitted to serve as the vapor control layer where, at its
    installed thickness or with a facer on its interior face, the exterior continuous insulation is a Class I or II vapor retarder.
    c. The requirements of this table apply only to continuous insulation used to control moisture in order to allow walls without a Class I, II or III interior vapor retarder. The insula-
    tion materials used to satisfy this option also contribute to but do not supersede the_building_ thermal envelope requirements of the_California Energy Code_.

    �

    EXTERIOR WALLS

  • § 1404.3 High relevance — show source text
    TABLE 1404.3(2)—VAPOR RETARDER OPTIONS Col2 Col3 Col4
    CLIMATE ZONE VAPOR RETARDER CLASS VAPOR RETARDER CLASS VAPOR RETARDER CLASS
    CLIMATE ZONE Ia IIa III
    1, 2 Not permitted Not Permitted Permitted
    3 Not permitted Permittedc Permitted
    4 (except Marine) Not permitted Permittedc See Table 1404.3(3)
    Marine 4, 5, 6, 7, 8 Permittedb, c Permittedc See Table 1404.3(3)
    a. A responsive vapor retarder shall be allowed on the interior side of any frame wall in all climate zones.
    b. In frame walls with a Class I vapor retarder on the exterior side, use of a Class I interior vapor retarder that is not a responsive vapor retarder shall require an_approved_ design.
    c. Where a Class I or II vapor retarder is used in combination with foam plastic insulating sheathing installed as continuous insulation on the exterior side of frame walls, the
    continuous insulation shall comply with Table 1404.3(4) and the Class I or II vapor retarder shall be a responsive vapor retarder.    		 a. A responsive vapor retarder shall be allowed on the interior side of any frame wall in all climate zones.
    b. In frame walls with a Class I vapor retarder on the exterior side, use of a Class I interior vapor retarder that is not a responsive vapor retarder shall require an_approved_ design.
    c. Where a Class I or II vapor retarder is used in combination with foam plastic insulating sheathing installed as continuous insulation on the exterior side of frame walls, the
    continuous insulation shall comply with Table 1404.3(4) and the Class I or II vapor retarder shall be a responsive vapor retarder.    		 a. A responsive vapor retarder shall be allowed on the interior side of any frame wall in all climate zones.
    b. In frame walls with a Class I vapor retarder on the exterior side, use of a Class I interior vapor retarder that is not a responsive vapor retarder shall require an_approved_ design.
    c. Where a Class I or II vapor retarder is used in combination with foam plastic insulating sheathing installed as continuous insulation on the exterior side of frame walls, the
    continuous insulation shall comply with Table 1404.3(4) and the Class I or II vapor retarder shall be a responsive vapor retarder.    		 a. A responsive vapor retarder shall be allowed on the interior side of any frame wall in all climate zones.
    b. In frame walls with a Class I vapor retarder on the exterior side, use of a Class I interior vapor retarder that is not a responsive vapor retarder shall require an_approved_ design.
    c. Where a Class I or II vapor retarder is used in combination with foam plastic insulating sheathing installed as continuous insulation on the exterior side of frame walls, the
    continuous insulation shall comply with Table 1404.3(4) and the Class I or II vapor retarder shall be a responsive vapor retarder.
    TABLE 1404.3(3)—CLASS III VAPOR RETARDERS Col2
    ZONE **CLASS III VAPOR RETARDERS PERMITTED FOR:a,
  • § 11.25 High relevance — show source text

    5 over 2 × 4 wall.| |6|Continuous insulation with_R_-value ≥ 11.25 over 2 × 6 wall.| |7|Continuous insulation with_R_-value ≥ 10 over 2 × 4 wall.| |7|Continuous insulation with_R_-value ≥ 15 over 2 × 6 wall.| |8|Continuous insulation with_R_-value ≥ 12.5 over 2 × 4 wall.
    Continuous insulation with_R_-value ≥ 20 over 2 × 6 wall.| |a. Vented cladding shall include vinyl, polypropylene, or horizontal aluminum siding, brick veneer with a clear airspace as specified in Table R703.8.4(1), rainscreen systems
    and other approved vented claddings.
    b. The requirements in this table apply only to insulation used to control moisture in order to permit the use of Class III vapor retarders. The insulation materials used to satisfy
    this option also contribute to but do not supersede the thermal envelope requirements of Chapter 11.|a. Vented cladding shall include vinyl, polypropylene, or horizontal aluminum siding, brick veneer with a clear airspace as specified in Table R703.8.4(1), rainscreen systems
    and other approved vented claddings.
    b. The requirements in this table apply only to insulation used to control moisture in order to permit the use of Class III vapor retarders. The insulation materials used to satisfy
    this option also contribute to but do not supersede the thermal envelope requirements of Chapter 11.|

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    WALL COVERING

    TABLE R702.7(4)—CONTINUOUS INSULATION WITH CLASS I OR II RESPONSIVE VAPOR RETARDER Col2
    CLIMATE ZONE PERMITTED CONDITIONSa
    3 Continuous insulation with_R_-value ≥ 2.
    4, 5 and 6 Continuous insulation with_R_-value ≥ 3 over 2 × 4 wall.
    Continuous insulation with_R_-value ≥ 5 over 2 × 6 wall.
    7 Continuous insulation with_R_-value ≥ 5 over 2 × 4 wall.
    Continuous insulation with_R_-value ≥ 7.5 over 2 × 6 wall.
    8 Continuous insulation with_R_-value ≥ 7.5 over 2 × 4 wall.
    Continuous insulation with_R_-value ≥ 10 over 2 × 6 wall.
    a. The requirements in this table apply only to insulation used to control moisture in order to permit the use of Class II vapor retarders. The insulation materials used to satisfy
    this option also contribute to but do not supersede the thermal envelope requirements of Chapter 11.    		 a. The requirements in this table apply only to insulation used to control moisture in order to permit the use of Class II vapor retarders. The insulation materials used to satisfy
    this option also contribute to but do not supersede the thermal envelope requirements of Chapter 11.
  • § 7.1 High relevance — show source text

    The total insulating value of materials to the interior side of the exterior continuous insulation, including any cavity insulation, shall not exceed R-5. Where the R-value of
    materials to the interior side of the exterior continuous insulation exceeds R-5, an approved design shall be required.
    b. A water vapor control material layer having a permeance not greater than 1 perm in accordance with ASTM E96 Procedure A (dry cup) shall be placed on the exterior side of
    the wall and to the interior side of the exterior continuous insulation. The exterior continuous insulation shall be permitted to serve as the vapor control layer where, at its
    installed thickness or with a facer on its interior face, the exterior continuous insulation is a Class I or II vapor retarder.
    c. The requirements in this table apply only to insulation used to control moisture in order to allow walls without a Class I, II or III interior vapor retarder. The insulation materi-
    als used to satisfy this option also contribute to but do not supersede the thermal envelope requirements of the_California Energy Code_.|a. The total insulating value of materials to the interior side of the exterior continuous insulation, including any cavity insulation, shall not exceed R-5. Where the R-value of
    materials to the interior side of the exterior continuous insulation exceeds R-5, an approved design shall be required.
    b. A water vapor control material layer having a permeance not greater than 1 perm in accordance with ASTM E96 Procedure A (dry cup) shall be placed on the exterior side of
    the wall and to the interior side of the exterior continuous insulation. The exterior continuous insulation shall be permitted to serve as the vapor control layer where, at its
    installed thickness or with a facer on its interior face, the exterior continuous insulation is a Class I or II vapor retarder.
    c. The requirements in this table apply only to insulation used to control moisture in order to allow walls without a Class I, II or III interior vapor retarder. The insulation materi-
    als used to satisfy this option also contribute to but do not supersede the thermal envelope requirements of the_California Energy Code_.|

    R702.7.1 Spray foam plastic insulation for moisture control with Class II and III vapor retarders. For purposes of compliance with Tables R702.7(3) and R702.7(4), spray foam with a maximum permeance of 1.5 perms at the installed thickness applied to the interior side of wood structural panels, fiberboard, insulating sheathing or gypsum shall be deemed to meet the continuous insulation moisture control requirement in accordance with one of the following conditions:

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

    R702.7.2 Vapor retarder installation. Vapor retarders shall be installed in accordance with the manufacturer’s instructions, accepted installation methods or an approved design. Where a vapor retarder also functions as a component of a continuous air barrier, the vapor retarder shall be installed as an air barrier in accordance with Section N1102.5.1.1.

    R702.7.3 California Energy Code and International Energy Conservation Code Climate Zones. The IECC climate zones used by this section differ from those used by the California Energy Code to determine applicability of energy efficiency measures. Comparison of IECC and California Energy Code climate zones is shown in Table R702.7.3.

    |TABLE R702.7.3—IECC VS.

  • § 7-8 High relevance — show source text

    The insulation materials used to satisfy
    this option also contribute to but do not supersede the thermal envelope requirements of Chapter 11.|

    7-8 2025 CALIFORNIA RESIDENTIAL CODE

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

    WALL COVERING

    TABLE R702.7(4)—CONTINUOUS INSULATION WITH CLASS I OR II RESPONSIVE VAPOR RETARDER Col2
    CLIMATE ZONE PERMITTED CONDITIONSa
    3 Continuous insulation with_R_-value ≥ 2.
    4, 5 and 6 Continuous insulation with_R_-value ≥ 3 over 2 × 4 wall.
    Continuous insulation with_R_-value ≥ 5 over 2 × 6 wall.
    7 Continuous insulation with_R_-value ≥ 5 over 2 × 4 wall.
    Continuous insulation with_R_-value ≥ 7.5 over 2 × 6 wall.
    8 Continuous insulation with_R_-value ≥ 7.5 over 2 × 4 wall.
    Continuous insulation with_R_-value ≥ 10 over 2 × 6 wall.
    a. The requirements in this table apply only to insulation used to control moisture in order to permit the use of Class II vapor retarders. The insulation materials used to satisfy
    this option also contribute to but do not supersede the thermal envelope requirements of Chapter 11.    		 a. The requirements in this table apply only to insulation used to control moisture in order to permit the use of Class II vapor retarders. The insulation materials used to satisfy
    this option also contribute to but do not supersede the thermal envelope requirements of Chapter 11.
    TABLE R702.7(5)—CONTINUOUS INSULATION ON WALLS WITHOUT A CLASS I, II OR III INTERIOR VAPOR RETARDERa Col2
    CLIMATE ZONE PERMITTED CONDITIONSb, c
    4 Continuous insulation with_R_-value ≥ 4.5
    5 Continuous insulation with_R_-value ≥ 6.5
    6 Continuous insulation with_R_-value ≥ 8.5
    7 Continuous insulation with_R_-value ≥ 11.5
    8 Continuous insulation with_R_-value ≥ 14
    a. The total insulating value of materials to the interior side of the exterior continuous insulation, including any cavity insulation, shall not exceed R-5. Where the R-value of
    materials to the interior side of the exterior continuous insulation exceeds R-5, an approved design shall be required.
    b. A water vapor control material layer having a permeance not greater than 1 perm in accordance with ASTM E96 Procedure A (dry cup) shall be placed on the exterior side of
    the wall and to the interior side of the exterior continuous insulation. The exterior continuous insulation shall be permitted to serve as the vapor control layer where, at its
    installed thickness or with a facer on its interior face, the exterior continuous insulation is a Class I or II vapor retarder.
    c. The requirements in this table apply only to insulation used to control moisture in order to allow walls without a Class I, II or III interior vapor retarder. The insulation materi-
    als used to satisfy this option also contribute to but do not supersede the thermal envelope requirements of the_California Energy Code_.    		 a. The total insulating value of materials to the interior side of the exterior continuous insulation, including any cavity insulation, shall not exceed R-5.
  • California Energy Code High relevance — show source text
    TABLE R702.7(2)—VAPOR RETARDER OPTIONS Col2 Col3 Col4
    CLIMATE ZONE VAPOR RETARDER CLASS VAPOR RETARDER CLASS VAPOR RETARDER CLASS
    CLIMATE ZONE CLASS Ia CLASS IIa CLASS III
    1, 2 Not Permitted Not Permitted Permitted
    3, 4 (except Marine 4) Not Permitted Permittedc Permitted
    Marine 4, 5, 6, 7, 8 Permittedb, c Permittedc See Table R702.7(3)
    a. A responsive vapor retarder shall be allowed on the interior side of any frame wall in all climate zones.
    b. In frame walls, use of a Class I vapor retarder that is not a responsive vapor retarder on the interior side with a Class I vapor retarder on the exterior side shall require an
    approved design.
    c. Where a Class I or II vapor retarder is used in combination with foam plastic insulating sheathing or insulated siding installed as continuous insulation on the exterior side of
    frame walls, the continuous insulation shall comply with Table R702.7(4) and the Class I or II vapor retarder shall be a responsive vapor retarder_._    		 a. A responsive vapor retarder shall be allowed on the interior side of any frame wall in all climate zones.
    b. In frame walls, use of a Class I vapor retarder that is not a responsive vapor retarder on the interior side with a Class I vapor retarder on the exterior side shall require an
    approved design.
    c. Where a Class I or II vapor retarder is used in combination with foam plastic insulating sheathing or insulated siding installed as continuous insulation on the exterior side of
    frame walls, the continuous insulation shall comply with Table R702.7(4) and the Class I or II vapor retarder shall be a responsive vapor retarder_._    		 a. A responsive vapor retarder shall be allowed on the interior side of any frame wall in all climate zones.
    b. In frame walls, use of a Class I vapor retarder that is not a responsive vapor retarder on the interior side with a Class I vapor retarder on the exterior side shall require an
    approved design.
    c. Where a Class I or II vapor retarder is used in combination with foam plastic insulating sheathing or insulated siding installed as continuous insulation on the exterior side of
    frame walls, the continuous insulation shall comply with Table R702.7(4) and the Class I or II vapor retarder shall be a responsive vapor retarder_._    		 a. A responsive vapor retarder shall be allowed on the interior side of any frame wall in all climate zones.
    b. In frame walls, use of a Class I vapor retarder that is not a responsive vapor retarder on the interior side with a Class I vapor retarder on the exterior side shall require an
    approved design.
    c. Where a Class I or II vapor retarder is used in combination with foam plastic insulating sheathing or insulated siding installed as continuous insulation on the exterior side of
    frame walls, the continuous insulation shall comply with Table R702.7(4) and the Class I or II vapor retarder shall be a responsive vapor retarder_._

    |TABLE R702.

Frequently asked questions

When does Table 1404.3(4) apply?

Table 1404.3(4) applies when a Class I or II responsive vapor retarder is used in combination with foam plastic insulating sheathing or exterior continuous insulation on the exterior side of framed walls; the table sets the minimum exterior continuous R‑values required to permit those vapor retarders (see § 1404.3).

What qualifies as “vented cladding”?

The code lists examples such as vinyl lap siding, polypropylene, horizontal aluminum siding, brick veneer with an airspace, and rainscreen systems as vented cladding; check the relevant table notes for the full list and approved alternatives (see Table 1404.3(3)).

Can spray foam substitute for the Table R‑value?

Yes — per § 1404.3.1, interior‑applied spray foam with an installed permeance ≤ 1.5 perms can satisfy the continuous‑insulation moisture‑control requirement if its R‑value alone meets the Table requirement or if the combined R of the spray foam and exterior continuous insulation meets the Table requirement.

Do the Table 1404.3(4) R‑values replace energy‑code insulation requirements?

No. The table values are for moisture control to permit Class I/II vapor retarders; those insulation materials also “contribute to but do not supersede” the California Energy Code thermal envelope requirements.

What if I put a Class I vapor retarder on both sides of a wall?

Using a Class I vapor retarder on the interior in addition to one on the exterior (where the interior retarder is not a responsive retarder) will require an approved hygrothermal design per the vapor retarder options and notes in § 1404.3.

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Related in the California Energy Code

Continuous insulation R‑value requirements to allow interior vapor retarders (1404.3 tables)

Vapor retarder installation requirements and spray foam criteria for moisture control

Residential continuous insulation tables and limits (R702.7(4) and R702.7(5))

Moisture control, continuous insulation and thermal‑bridging controls

California Energy Code