Outright ADU permit denials are uncommon in California, because state law limits the reasons a city can deny a compliant ADU. Most “rejections” are incomplete-application notices or plan check corrections. The usual causes are incomplete plans, the wrong jurisdiction, overlays found late, utility capacity, and fire requirements.
If your application bounced, it’s probably one of these eight. Here’s each one and the fix.
1. Was the plan set incomplete?
Missing structural calculations, no Title 24 energy report, a site plan without dimensions, or elevations without heights will stop a review. Fix: use a designer who prepares ADU permit sets regularly, and check the city’s or county’s submittal list before you submit.
2. Did you submit to the wrong agency?
Parcels in Valencia, Newhall, Saugus, and Canyon Country go to the City of Santa Clarita. Stevenson Ranch, Castaic, Acton, and Agua Dulce go to LA County. Some addresses near city edges surprise people. Fix: confirm your jurisdiction before anything else.
3. Was an overlay discovered late?
Hillside, high fire hazard, flood, and oak tree conditions add requirements standard plans may not cover. Fix: check your parcel’s overlays during feasibility, before paying for plans.
4. Were there utility capacity problems?
An electrical panel too small with no upgrade shown, an inadequate sewer lateral, or septic capacity that can’t handle the added bedrooms will send plans back. Fix: confirm panel size, sewer or septic, and water service in writing before design. See ADUs on septic and well.
5. Were fire sprinklers missed?
If the main house is required to have sprinklers, the ADU likely needs them, and that affects water service and ceiling design. Fix: confirm sprinkler requirements early. See ADU fire sprinkler rules.
6. Were setbacks or height miscalculated?
Designing to outdated numbers, or drawing a detached ADU taller than the 16-foot limit that applies to most lots, triggers corrections. Fix: design to current state and local standards. See ADU size, setback, height, and parking rules.
7. Did the HOA object after the city approved?
The city and your HOA are separate reviews. Fix: start HOA review the same week you submit to the city or county. See HOAs and ADUs.
8. Was owner-builder paperwork incomplete?
Owner-builders must complete specific disclosures and take responsibility for inspections and anyone working on the job. Fix: unless you’ve done it before, have a licensed contractor pull the permit.
What’s the difference between a correction and a denial?
A correction notice is normal. The reviewer lists issues, your designer fixes them, and you resubmit. A denial is a formal refusal. Because state law limits the grounds for denying a compliant ADU, true denials are uncommon. If you get one that seems to conflict with state law, use the agency’s appeal process. You can also contact the California Department of Housing and Community Development (HCD), which enforces state ADU law.
What deadlines does the city or county have to meet?
Since January 1, 2026, the agency must tell you within 15 business days whether your application is complete and list what’s missing. It must approve or deny a complete application within 60 days. Under AB 3182, a complete application that isn’t acted on in 60 days is deemed approved. See how long an ADU permit takes.
Want help getting a clean permit set?
Call (661) 486-8393. If no one answers, leave a voicemail with your name, phone number, address, and the type of ADU you want. You can also use the contact form. We’ll pass your details to a local ADU contractor, who will follow up with you directly. There’s no obligation to hire.
ADU permit rejection FAQs
Can a city deny an ADU that meets state law?
Its options are limited. A compliant ADU gets ministerial review, and the city must act within 60 days of a complete application.
How many correction rounds are normal?
Many applications get at least one round of corrections. Clean, complete plans from an ADU-experienced designer usually need fewer.
Who enforces state ADU law?
The California Department of Housing and Community Development (HCD) reviews local ADU ordinances and handles complaints about local agencies that don’t follow state ADU law.
Does the 60-day clock run while I fix corrections?
No. The 60-day period covers the agency’s review of a complete application. Time spent revising plans doesn’t count against the agency.