National Coatings Blog

2023 New Building Code - CA Minimum Insulation Requirements

Posted by Nicole Gale on Tue, Feb 28, 2023 @ 07:34 PM

Insulation Building Code 2023


  • The insulation requirements for roof alterations apply to all roof replacements and recovers regardless of whether existing insulation is located above or below the roof deck.

  • The prescriptive minimum requirements for roof alterations are:

    • R-17 or R-23 (depending on climate zone) with the use of continuous insulation (ci) only; or

    • U-0.042 or U-0.037 (depending on climate zone) if the insulation is a combination of continuous and cavity insulation. Assemblies insulated with cavity insulation must have a minimum R-10ci installed above the roof deck.

  • There are two exceptions that include important backstops:

    • Roof Recovers: Recovers are not required to meet the full R-17/23 (or U-0.037/0.042) requirements if at least R-10ci of new insulation is installed above the roof deck.

    • Equipment Curbs and Flashing Heights: The maximum amount of insulation (up to the prescriptive requirement) or R-10ci, whichever is greater, must be installed where flashing heights associated with HVAC equipment curbs present limiting conditions.


  • The California Energy Commission’s web-based tool for locating the Climate Zone applicable to a specific project can be accessed here.
  • The California 2022 Energy Code, Reference Appendices (including JA4), Climate Zone Maps, and the 2022 Multifamily and Nonresidential Compliance Manual can be accessed here.
  • Energy Code Ace tools, training, and resources (including fact sheets) can be accessed here.

Insulation Chart 2023

Get the Entire 2023 Energy Code Requirement Here