Skip to content
OwnAdu

Phase 03 of 06

Phase 3: ADU permits

Permitting is where ADU projects most often stall. California law mandates 60-day approval for complete applications, but the practical timeline depends on submittal quality and your city. Set realistic expectations here and the project moves; underestimate it and you lose months.

Typical duration

4–16+ weeks (state mandate: 60 days for complete applications)

Typical phase cost

$12,000–$77,000 total in California (varies wildly by city)

What California state law actually requires in 2026

California has moved aggressively over the past several years to preempt local ADU restrictions. The 2026 framework, summarized from the California Department of Housing and Community Development (HCD) March 2026 ADU Handbook update and Andalusia Drafting's 2026 permit guide:

  • Ministerial review (AB 881). Cities must approve compliant ADU applications within 60 days of receiving a complete application — no public hearings, no neighbor appeals.
  • 15-day completeness review (SB 543). The city must decide whether your application is complete within 15 business days. An incomplete app doesn't start the 60-day clock — which is why first-submittal quality matters more than city efficiency.
  • Pre-approved plans. 30-day review when you use one of your city's pre-approved standard plans. LADBS has 20+ free plans; San Jose, San Diego, Berkeley, and Sacramento have similar catalogs.
  • Coastal Development Permits (AB 462). Properties in the California Coastal Zone now have CDP review processed concurrently with building permits within 60 days, instead of sequentially.
  • Legalization path (AB 2533, effective Jan 1 2025). Unpermitted ADUs built before January 1, 2020 can be legalized through a streamlined process without health-and-safety penalties.
  • Multifamily expansion (SB 1211, 2025). Multifamily lots can now add up to 8 detached ADUs (previously 2).
  • Impact fee exemption. ADUs under 750 sq ft are partially or fully exempt from impact fees statewide under SB 13 and follow-on legislation. Above 750 sq ft, proportional impact fees apply.

What's actually in the permit submittal

A complete California ADU submittal in 2026 typically includes:

  • Architectural drawings (site plan, floor plans, elevations, sections, details)
  • Structural drawings and calculations stamped by a licensed California engineer
  • Title 24 energy compliance (CF-1R form and supporting calculations)
  • Soils report (often required for new foundations, especially on hillside lots)
  • Mechanical, electrical, and plumbing plans
  • Survey (for tight lots) and grading/drainage plans when applicable
  • Application fees (separate from impact fees, which come at issuance)

A complete, well-prepared submittal moves through plan check in one or two cycles — Andalusia Drafting reports 60-day approvals in over 85% of cases when submitting complete plan sets that anticipate each city's specific requirements. An incomplete or sloppy submittal will be returned, restarting the 15-day completeness clock and adding 3–8 weeks per correction cycle.

Permit and impact fees by California city in 2026

California permit costs vary dramatically by jurisdiction. Total permit-related costs (direct permit fees + professional soft costs + utility connections) range from $12,000 to $77,000 across the state (Andalusia Drafting, 2026). Specific city brackets:

  • Inland Empire (Riverside, Corona, Moreno Valley): $8,000–$15,000 direct permit fees; total all-in $12,000–$22,000. The lowest-cost permitting market in California (Dynamic Quality Builders, 2026).
  • San Diego: $1,800–$3,000 typical building permit fee plus impact fees; 50–75 day timelines for standard ADUs. Coastal Overlay Zone properties require concurrent CDP review per AB 462.
  • San Jose: 35–55 day actual timelines — the fastest in California in 2026 (Andalusia Drafting). The city publishes a Building Fee Estimator on its planning portal.
  • Los Angeles: $1,800–$2,800 typical building permit fee plus construction fees of $2,000–$10,000 (Aduwestcoast 2026). LADBS pre-approved plans cut review to 50–70 days; custom plans run 8–16 weeks. Total all-in permit costs $15,000–$25,000 (DQB).
  • Orange County: $12,000–$20,000 permit-related, 6–12 week timelines. HOA review adds time and complexity (DQB).
  • Ventura County: $10,000–$18,000 permit costs, 6–10 week timelines. WUI fire zones may add fire-resistant construction requirements (DQB).
  • San Francisco: The state's highest permit fees at 6–9% of construction cost (Andalusia Drafting). Total all-in $33,000–$57,000. SF's two-agency process (DBI + Planning) adds a second review timeline to every project, though DBI's 100% electronic review is the most modern in the state.

Sacramento sits between Inland Empire and the Bay Area at roughly $1,200–$2,000 in baseline permit fees. Outside California, expect permit costs to track 30–60% lower because fewer states impose California's Title 24 energy compliance and seismic engineering requirements.

The plan-check correction cycle

Expect 1–3 rounds of corrections, with each cycle taking 3–8 weeks to come back. SnapADU notes that even thorough plans see at least one round of corrections — this is universal, not a sign of a bad designer. Common correction categories:

  • Setback or height calculations the plan-checker reads differently
  • Structural calculations needing clarification or additional details
  • Title 24 / energy compliance worksheets that need updates
  • Fire-rated assembly details near property lines
  • Drainage and grading requirements
  • Connection specifications and shear wall analysis for hillside lots

Most corrections are routine. The slowdown isn't the plan-checker's comments — it's how fast your design team responds. SnapADU reports that using a third-party permitting agency (rather than keeping design and permitting in one firm) adds up to 6 weeks because each hand-off adds days. Design-build firms with in-house permitting consistently move fastest.

What to do while you wait

Use the permit weeks productively:

  • Finalize your financing. Lenders need permits or near-permits to fund construction loans.
  • Solidify your builder shortlist. If you're going to bid, send out documents and gather written quotes.
  • Order long-lead items (windows, doors, custom cabinetry) with 12–20 week lead times. Material lead times are one of SnapADU's top seven project-delay drivers.
  • Confirm your insurance plan with your carrier — many require a builder's risk policy during construction.

The cost of skipping permits

Don't. Andalusia Drafting documents the consequences from California jurisdictions: fines from $500 to $30,000+, stop-work orders, forced demolition, title issues that block resale, denied insurance claims, and personal liability exposure. The legalization path under AB 2533 is real, but it's a permit process — not a permission slip. Doing the permit work up front is always cheaper than fixing the consequences later.

Once your permit is approved, you're ready for Phase 4 — Financing (if you haven't locked it already) and Phase 5 — Construction.

Have questions about your phase 03 decisions?

Get the free Homeowner's Playbook — full breakdown of every phase, with checklists.

By submitting, you consent to OwnAdu and up to three vetted ADU builders contacting you by email about your project. Consent is not a condition of purchase. Unsubscribe at any time via the link in any email. See our Privacy and Terms.

← Previous phase

Design

Next phase →

Financing