California's ADU code has been rewritten almost every year since 2017. The direction has been consistent: fewer restrictions, more units, faster approvals.
Here are the rules that actually matter for San Diego homeowners in 2026.
1. Your HOA almost certainly can't block you
AB 670 (2020) and its follow-ons stripped HOAs of most of their authority to prohibit ADUs on single-family lots. Architectural-committee reviews are still allowed — your HOA can require your ADU look like the rest of the neighborhood — but outright bans are not enforceable.
What this means in practice: if your CC&Rs say "no secondary dwellings," that language is overridden by state law.
2. You don't have to live in either unit
The owner-occupancy requirement was suspended statewide through 2025 and has been extended indefinitely via AB 1033 and related bills. You can build, rent the ADU, rent the main house, or live in either — your choice.
This is a quiet change with huge investor implications. Absentee-owner ADUs are now legal statewide.
3. Most lots can fit more than one ADU
Under current California law, most R-1 lots are entitled to:
- One detached or attached ADU (up to 1,200 sqft)
- One Junior ADU inside the primary residence (up to 500 sqft)
That's three legal units on an R-1 lot. And under SB 9 (2021), many R-1 lots qualify for additional pathways:
- SB 9 lot split — divide one R-1 lot into two conforming lots, each of which can then host its own duplex or single-family home plus ADU.
- SB 9 duplex conversion — convert a single-family home into a duplex on an R-1 lot.
Stacked together, some qualifying lots can legally produce four to six doors. Few homeowners know this.
4. The city has 60 days to review your permit
Under AB 68 and its updates, jurisdictions have 60 days from a complete submission to approve or deny an ADU permit. After 60 days, approval is effectively deemed — though nobody wants to rely on that legal technicality.
What this means for you: your permit should not take six months in 2026 if the submission is clean. If it does, your builder didn't submit a clean package.
5. Parking rules are now minimal
AB 671 and follow-ons eliminated parking requirements for ADUs located within a half-mile of public transit. In practice, that's most of urban San Diego. If your builder tells you you need to build a parking space for your ADU, ask whether the half-mile transit exemption applies.
6. State density bonus can unlock even more
For qualifying rent-restricted affordable projects, California's density bonus law allows up to four total units on an R-1 lot. The rent restrictions are real — you're trading density for affordability covenants — but for the right investor, the math works.
Where the rules still bite in San Diego
State ADU law is permissive, but local overlays still apply in four places:
1. Coastal Zone — Encinitas, Carlsbad, Del Mar, Solana Beach, and parts of SD proper require a Coastal Development Permit in addition to a building permit. Adds 2–6 months. 2. Historic overlays — blocks in North Park, Mission Hills, Banker's Hill, and Sherman Heights have historic review that adds 1–3 months. 3. Fire severity zones — East County and inland North County require fire-rated assemblies. Cost impact, not timeline. 4. Slope and geotech — not a legal rule, but a practical one. Steep lots need engineering.
The changes we're watching in 2026
- SB 1211 amendments — proposed expansions to the number of ADUs allowed on multi-family parcels.
- Coastal Commission ADU policy — expected clarification on how coastal jurisdictions apply state ADU law.
- Parking on ADUs — further loosening expected.
The takeaway
If you bought your San Diego home before 2017, the ADU law has changed four or five times since. What wasn't legal then probably is now. What required owner-occupancy then doesn't now. What was blocked by your HOA then isn't now.
The only reliable way to know what your specific lot is entitled to is a Property Feasibility Analysis. [Request one from ADU PALS →](/contact)
