Is any project too small for Title 24?

No project is too small for the rules to apply, because the Energy Code has no size threshold. What can be waived is the paperwork: the building department may decide not to require a certificate of compliance for some small alterations and for additions under 300 square feet that need no field verification. That decision belongs to the department.

Is a re-roof a repair or an alteration?

An alteration. Section 100.1 treats replacing any component that has requirements in the Standards as an alteration rather than a repair, and the Energy Commission's manual gives re-roofing as an example.

Can a new home still have a gas furnace?

Under the state Energy Code, yes, through the performance approach, provided the design makes up the extra energy elsewhere. The prescriptive package assumes a heat pump. Local ordinances can be stricter, so check with the building department.

Can I submit a 2022-code report with a permit application made today?

Not for an ordinary project. Applications submitted on or after 1 January 2026 are checked against the 2025 Energy Code. Homes rebuilt under Executive Order N-29-25 after the January 2025 Los Angeles-area fires are one of the few exceptions.

10 Title 24 Myths, and the Code Sections That Settle Them

Most Title 24 myths grew from something that used to be true, or that is true for a neighbouring case. Here are the ten that cost people the most time, each with the section of the 2025 Energy Code, or the Energy Commission's own guidance, that settles it.

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Each myth here is held in good faith, usually because it was once true or holds for a neighbouring case. The section numbers let you check every correction; Title 24 requirements gives the overview.

1. "It's a small job, so Title 24 doesn't apply"

Part 6 sets no size threshold. Its Section 100.1 definition makes any change to water heating, space conditioning, lighting, electrical power distribution or the envelope an alteration, one light fixture included. Paperwork is another matter: Part 1, Section 10-103(a)1C lets the building department waive or simplify the certificate for some small jobs with no field verification, while warning that a waiver licenses nothing the code forbids. Do I need a Title 24 report? has examples.

2. "Replacing like for like is a repair"

The Section 100.1 definition of a repair closes this gap itself: replacing any component, system or equipment for which there are requirements in the Standards "is considered an alteration and not a repair." A water heater, a heat pump or a re-roof all count. The real exception is glazing: new glass in an existing sash and frame, or a new sash in an existing frame, is a repair if it performs at least as well (note to Section 150.2(b)1B).

3. "Once plan check is done, the field test is a formality"

Field verification was called HERS testing until it was renamed under the ECC Program on 1 January 2026, and nothing about it became optional. Section RA2.4.4 of the Reference Appendices says the department shall not approve the dwelling until it has the registered CF3Rs from an ECC-Rater, so a skipped test resurfaces at final. See how to prepare for an ECC-Rater visit.

4. "The report from last year still works"

Only for a permit applied for under that edition. Part 1, Section 10-103(d)1 ties a permit to the Part 6 requirements in effect on the date it was applied for; since 1 January 2026 that means the 2025 code, and an expired permit with no work under it is judged afresh on the new application's date. HCD Information Bulletin 2025-03 notes that the application date is generally set by the local government. Narrow exceptions exist: rebuilds under Executive Order N-29-25 (see rebuilding after a wildfire) and the model-home rule in can you reuse a Title 24 report?

5. "Every new building needs solar panels"

Section 150.1(c)14 puts PV on newly constructed single-family buildings, and even there it has exits. No PV is required where the solar access roof area is under 80 contiguous square feet (Exception 1), where Equation 150.1-C gives less than 1.8 kWdc (Exception 2), or where the department finds the roof cannot carry PV under the ASCE 7-16 snow-load chapter (Exception 3). A JA12 battery lets the size drop by 25 per cent (Exception 5). Additions and alterations sit outside the section, and the Energy Commission has said ADUs created within existing space, or as additions, are not subject to it. See residential solar requirements.

6. "Title 24 is basically insulation"

Insulation is simply the part people see. Section 100.0(b) lists what Part 6 covers: the building envelope, space conditioning, water heating, pools, spas, solar-ready buildings, indoor lighting, outdoor lighting, electrical power distribution and signs. Title 24 itself is the whole California Building Standards Code. The Building Standards Commission lists its parts: the Building Code in Part 2, the Residential Code in Part 2.5, electrical, mechanical and plumbing codes in Parts 3 to 5, the Energy Code in Part 6, the Wildland-Urban Interface Code in Part 7, the Fire Code in Part 9, the Existing Building Code in Part 10 and CALGreen in Part 11. A Title 24 report is about Part 6 alone.

7. "California has banned gas in new homes"

The Energy Commission's 2025 fact sheet says it "does not mandate specific fuel types." The prescriptive package does assume electric equipment: Section 150.1(c)6 for space heating, Section 150.1(c)8 for water heating, where the options are a 240-volt heat pump water heater, one meeting the NEEA Advanced Water Heater Specification Tier 3, or solar water heating with electric backup. A gas furnace or water heater still complies on the performance path when its extra energy is offset elsewhere, and its presence triggers the electric-ready wiring of Sections 150.0(n), (t), (u) and (v). Some local governments have gone further, so the answer can depend on the address; see do new homes have to be all-electric?

8. "An unconditioned building is outside the code"

Section 100.0(a) brings unconditioned buildings within Part 6 alongside conditioned ones, and Section 100.0(c) applies the lighting rules to unconditioned space. The single-family building definition in Section 100.1 includes an Occupancy Group U building on a residential site, so a detached garage or workshop is covered. Its envelope is unregulated while it stays unconditioned; its hardwired lighting is not. Add heating or cooling and it becomes newly conditioned space, held to the rules for an addition. See accessory structures and unconditioned space.

9. "Any double-pane window will pass"

Pane count is not a rating. A replacement window must meet the U-factor and solar heat gain coefficient of Table 150.1-A for its climate zone (Section 150.2(b)1B): U-0.27 in zones 1 to 5, 11 to 14 and 16, U-0.30 elsewhere, with an SHGC cap in most zones. A small-job allowance lets up to 75 square feet of replacement windows meet U-0.40 instead, with SHGC no higher than 0.35 in zones 2, 4 and 6 to 15. The values come from NFRC 100 and NFRC 200 ratings under Section 110.6(a). See windows and Title 24.

10. "A house lost to fire can be rebuilt to its old specification"

The compliance manual's Example 1-1 answers this: buildings destroyed or damaged by natural disasters must meet the Energy Code in effect when the permit is applied for, for the portions being rebuilt. A 1970s house rebuilt today is held to the 2025 code. Executive Order N-29-25 makes an exception for homes lost in the January 2025 Los Angeles-area fires, which may stay on the 2022 code without PV or a battery.