Title 24 vs Title 25: What Is the Difference?
They are separate titles of the California Code of Regulations. Title 24 is the California Building Standards Code, and its Part 6 is the Energy Code. Title 25 is the housing title, with the Department of Housing and Community Development’s regulations for State Housing Law, mobilehome parks and manufactured housing. For a site-built building, the energy report comes from Title 24.
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What each title holds
The Building Standards Commission’s guide says the Code of Regulations has 28 titles, each on a subject, and names housing as Title 25. Title 24 is reserved for building standards: the rules for designing and constructing buildings and their equipment. HCD’s own State Housing Law page draws the line the same way. Building standards are published in Title 24, and HCD’s regulations are published in Title 25, Division 1, Chapter 1.
Where the two meet
- Manufactured homes. The Energy Commission’s compliance manual says Title 25, not Title 24, governs manufactured homes, additions to the unit included. HCD publishes the manufactured housing regulations in Title 25, Division 1, Chapter 3, Subchapter 2, from Section 4000. See manufactured homes and Title 24.
- Factory-built housing. It is designed to Title 24, but HCD’s bulletin on the 2025 code cites Title 25 Section 3048 for the rule that approved plans stay valid for 36 months. See prefab ADUs and Title 24.
- Mobilehome and special occupancy parks. HCD adopts the building standards for permanent buildings in these parks, and enforcement follows the Mobilehome Parks Act, the Special Occupancy Parks Act and their Title 25 regulations. In some places a local agency has taken over that enforcement, so the agency on your permit is the one to ask.
Which one a document comes from
A CF1R, CF2R or CF3R is a Title 24, Part 6 document, and the parts of Title 24 shows where Part 6 sits among the others. A plan check comment that cites a Title 25 section is about HCD’s housing regulations, not the Energy Code. A comment that cites Title 20 is about appliance efficiency, which is the Energy Commission’s own title; see Title 24 versus Title 20.
If you are unsure what governs your home or park, what Title 24 is and do I need a Title 24 report are the places to start.
Common Title 24 Questions
- What is Title 24?
- Do I need a Title 24 report?
- How much does a Title 24 report cost?
- How long does a Title 24 report take?
- What is included in a Title 24 report?
- What plans do I need to upload?
Frequently Asked Questions
The Energy Commission’s manual says Title 25, not Title 24, governs manufactured homes, including additions to the unit. A site-built structure on the same lot is different and does need energy documents.
No. That code is Title 24. HCD publishes its building standards in Title 24 and its regulations in Title 25.
Title 20, the Energy Commission’s appliance efficiency regulations. It is neither Title 24 nor Title 25.
Explore What Is Title 24?
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View all What Is Title 24? guides → · Title 24 Guide · Title 24 guide