Decoding the New ADU Section Numbers
If you've been reading about ADUs for a few years, the citations stopped matching. The rules didn't vanish. They moved. Here's a map from the old numbers to the new ones, and what actually changed for 2026.
Published Nov 11, 2026
Pick up an ADU article from 2022 and you'll see "Government Code section 65852.2" on nearly every page. Pick up a plan check comment from this year and you'll see numbers like 66314 or 66323 instead.
Same subject. New addresses.
California reorganized its ADU law in 2024, then amended it again in 2025. For a Del Mar owner, the practical problem is simple: older guides, older city handouts and older designer notes may cite sections that no longer exist under those numbers. This note is a decoder.
What happened in 2024
SB 477 (Chapter 7, Statutes of 2024) didn't rewrite the rules. It moved them. According to the state housing department's ADU Handbook, ADU and junior ADU law was relocated from Government Code sections 65852.2, 65852.22, 65852.23 and 65852.26 into a new Chapter 13, sections 66310 through 66342. The handbook says the bill took effect March 25, 2024.
The new chapter has four articles:
| Article | Sections | Covers |
|---|---|---|
| 1. General provisions | 66310 to 66313.5 | Findings, HCD authority, definitions |
| 2. ADU approvals | 66314 to 66332 | Local ordinances, review, standards, fees |
| 3. Junior ADUs | 66333 to 66339 | JADU rules |
| 4. ADU sales | 66340 to 66342 | Condo-style separate sale, where a city opts in |
The conversions people ask about most
The handbook includes a full table. These are the rows that come up most in ordinary projects:
| Old citation | New citation | What it's about |
|---|---|---|
| 65852.2(j) and 65852.22(j) | 66313 | Definitions |
| 65852.2(a)(1)(A), (D), (a)(4)-(5) | 66314 | What a local ordinance must and may do |
| 65852.2(a)(3), (a)(7) | 66317 | Review timing |
| 65852.2(c) | 66321 | Size and setback floors |
| 65852.2(e) | 66323 | ADUs that must be approved on any qualifying lot |
| 65852.2(f) | 66324, later moved to 66311.5 | Fees |
| 65852.23 | 66332, later moved to 66311.7 | Unpermitted ADUs |
| 65852.22 | 66333 to 66339 | Junior ADUs |
| 65852.26 | 66340 and 66341 | Separate sale |
That "later moved" column matters. More on it below.
What changed for 2026
The 2025 session made real substance changes, mostly effective January 1, 2026. HCD's handbook summarizes SB 543 (Chapter 520, Statutes of 2025) in some detail. The changes most likely to touch a Del Mar project:
- Junior ADUs are measured by livable space. A JADU is now no more than 500 square feet of interior livable space. The current text of section 66313(d) says it must be contained entirely within a single-family residence.
- Size limits are based on interior livable space. The handbook notes that size limits in section 66321 are now measured that way.
- Fee lines. Impact fees can't be charged on an ADU with 750 square feet or less of interior livable space, or a JADU with 500 or less. Above 750, fees must be proportional to the primary dwelling.
- School fees. An ADU or JADU with less than 500 square feet of interior livable space doesn't count as added assessable space, which affects school fee calculations.
- Completeness letters. A permitting agency has 15 business days to tell you whether an application is complete. If it isn't, the notice must list what's missing and how to fix it.
- Appeals. Agencies must offer a way to appeal an incompleteness finding or denial, with a final written decision within 60 business days of the appeal.
The same session also renumbered three sections again. Per the handbook, 66324 became 66311.5, 66327 became 66313.5, and 66332 became 66311.7. Section 66333.5 was added.
Why this matters when you read a document
You're likely to run into old citations in three places.
Older city materials. Local handouts get updated on their own schedule. A city sheet written before 2024 may cite 65852.2 throughout. That doesn't make it wrong on substance, but it's worth checking the date at the bottom.
Designer notes and plan sets. Drawings carried forward from an earlier design may keep the old references in their general notes. Updating them is a small fix that saves a correction comment later.
Online articles. Much of what ranks well in search was written before the move. Read the date first.
What didn't change
The core structure of state ADU law is still there under new numbers. A few examples from the current text of section 66314:
- An ADU may be rented separately but generally not sold separately, except under the Article 4 rules.
- A detached ADU's total floor area can't exceed 1,200 square feet under that section.
- Side and rear setbacks for a new ADU can't be more than four feet.
- ADUs can't be required to provide fire sprinklers if the main house isn't required to have them.
Section 66314 itself was amended again by AB 1170, effective January 1, 2026, so even the new numbers keep moving. Always check the "amended by" line at the bottom of the official text.
Unpermitted units got more breathing room
One 2024 change matters to owners with an older backyard unit. HCD says a local agency can't deny a permit for an unpermitted ADU built before January 1, 2020 just because it violates building standards or doesn't meet ADU law or a local ordinance. Health and safety conditions still apply. That rule now sits at section 66311.7. Our legalization page covers the process.
How to check a citation yourself
- Note the old number and subsection.
- Find it in HCD's conversion table in the ADU Handbook.
- Open the new section on the state's legislative information site.
- Read the last line for the most recent amendment and effective date.
It takes five minutes and keeps you from relying on a rule that changed.
Del Mar's local layer
State law sets the floor. Del Mar's own ADU chapter, coastal permit process and design review sit on top of it. For the local side, start with our pages on ADU permits, ADU size and the coastal development permit. Our note on the 800 square foot floor covers one of the most important local rules.
This is general information, not legal advice. For a specific lot, the city planner and your design team have the final read.
Talk it through
We work with verified contractors who build ADUs in Del Mar and keep up with the code changes. Request a Free Quote to start a conversation about your lot.
Sources (accessed Nov 11, 2026): Accessory Dwelling Unit Handbook (2026 update) (California Department of Housing and Community Development) · Government Code section 66313 (definitions) (California Legislative Information) · Government Code section 66314 (California Legislative Information)