Why California ADU Permits Get Rejected in 2026: The Most Common Plan Check Corrections (and How to Avoid Them)
Last updated: September 29, 2026
Quick answer
Most California ADU permits are not denied outright. They are sent back with plan check corrections. The most common reasons are missing or inconsistent information across sheets, stair and egress details that don't meet the California Residential Code (CRC), incomplete Title 24 energy compliance forms, missing CALGreen notes, unclear site plan setbacks and utilities, and missing wildfire (WUI) construction details in fire hazard zones.
Each round of corrections can add weeks to an approval. The fastest way to avoid them is to check your full permit set against the current code, sheet by sheet, before you submit.
Why ADU plan check matters more in 2026
Three changes make a clean first submission more important this year.
- A new code cycle took effect on January 1, 2026. California adopted the 2025 edition of the California Building Standards Code (Title 24), including updated residential, energy and green building requirements. Plans prepared with old templates, notes or energy forms are a common source of corrections.
- State ADU law was reorganized. California's ADU statutes were moved into a new section of the Government Code (starting at Section 66310), and recent bills refined rules on setbacks, height and local review. Cities are updating their checklists to match, and reviewers expect plans to cite current requirements.
- Demand is high and review time is the bottleneck. State law generally requires cities to act on a complete ADU application within 60 days. But the clock applies to a complete application, so every correction round restarts part of the wait.
For designers and builders, each resubmittal costs unbilled hours. For homeowners, it means delayed construction, higher carrying costs and frustrated contractors.
What is plan check?
Plan check is the review a city or county building department performs on your construction drawings before issuing a permit. Reviewers confirm the design complies with the building, residential, energy, green building, fire and zoning codes that apply to the project.
If something is missing or non-compliant, the reviewer issues a correction list (also called plan check comments). You revise the drawings, respond to each comment, and resubmit. The permit is issued only after every comment is resolved.
A typical residential ADU permit set includes a cover sheet, site plan, floor plan, exterior elevations, building sections, structural sheets, MEP (mechanical, electrical, plumbing) plans, CALGreen notes and a Title 24 energy report.
The 14 most common ADU plan check corrections
Most corrections fall into a predictable set of issues. The table below groups them by the sheet where reviewers usually find them, with the fix for each.
| # | Sheet | Common correction | How to fix it before you submit |
|---|---|---|---|
| 1 | Cover sheet | Outdated code editions listed | List the 2025 California codes in effect since January 1, 2026 (CRC, CBC, CEC, CPC, CMC, Energy Code, CALGreen). |
| 2 | Cover sheet | Missing project data | Show APN, zoning, occupancy, construction type, lot area, existing and proposed floor area, and fire sprinkler status. |
| 3 | Cover sheet | Scope of work is vague | Describe the ADU type (detached, attached, conversion, JADU), square footage and all work included. |
| 4 | Site plan | Setbacks not dimensioned | Dimension distances from the ADU to all property lines and to other structures. |
| 5 | Site plan | Utilities not shown | Show water, sewer, gas and electrical routing, meter locations and any easements. |
| 6 | Site plan | Fire access or hazard zone not addressed | Note the Fire Hazard Severity Zone status and the path of travel for fire access where required. |
| 7 | Floor plan | Egress windows not specified | Label sleeping room windows with net clear opening, width, height and sill height to meet CRC R310. |
| 8 | Floor plan | Smoke and CO alarms missing | Show smoke alarms (CRC R314) and carbon monoxide alarms (CRC R315) in every required location. |
| 9 | Floor plan / sections | Stair dimensions non-compliant or missing | Dimension risers, treads, headroom, width and handrails per CRC R311.7. |
| 10 | Floor plan / sections | Guards missing or unclear | Show guard height and baluster spacing at decks, lofts and stairs per CRC R312. |
| 11 | Elevations | Heights don't match zoning limits | Dimension building height from grade and confirm it against local and state ADU height limits. |
| 12 | Sections | Insulation and assemblies don't match energy report | Make wall, roof and floor assemblies on the sections match the Title 24 report exactly. |
| 13 | Title 24 energy | CF1R missing, unsigned or inconsistent | Include a signed CF1R. Match square footage, glazing, HVAC, water heating and solar PV to the drawings. |
| 14 | CALGreen | Mandatory measures not on the plans | Add the CALGreen residential mandatory measures checklist and required notes (EV readiness, water-efficient fixtures, construction waste). |
Notice a pattern: many corrections are consistency errors, not design errors. The floor plan says one thing, the energy report says another, and the reviewer has to send it back. These are the hardest issues to catch by eye and the easiest to catch with a systematic cross-sheet check.
Extra checks for wildfire zones
If the property is in a Fire Hazard Severity Zone or Wildland-Urban Interface area, reviewers also look for ignition-resistant construction per CRC R337 and CBC Chapter 7A. That includes Class A roofing, ember-resistant vents, compliant exterior wall coverings, tempered or multi-pane glazing, and defensible space notes. Missing WUI notes are a frequent correction in hillside and foothill communities across the Bay Area.
ADU pre-submission checklist
Run through this list before you upload your permit set. It takes less time than a single correction round.
- Cover sheet lists the current 2025 California code editions
- Project data, scope of work and sheet index are complete
- Every sheet in the index is actually in the set
- Site plan dimensions all setbacks, utilities and easements
- Fire Hazard Severity Zone status is stated, with WUI details if applicable
- Egress windows, smoke alarms and CO alarms are shown and labeled
- Stairs and guards are fully dimensioned
- Building height is dimensioned and checked against the height limit
- Assemblies on the sections match the Title 24 energy report
- CF1R is signed and matches the drawings
- CALGreen mandatory measures are on the plans
- Existing and proposed conditions are clearly distinguished on every sheet
- Your city's local ADU checklist has been reviewed for extra requirements
Local requirements vary. Always confirm your city or county's own ADU submittal checklist, because many jurisdictions add requirements beyond state code.
How zHeight helps you get approved faster
zHeight designs permit-ready ADU, addition, remodel and new construction plans for Bay Area homeowners and builders, with code compliance built in from the first sheet. With 225+ projects completed across 52+ jurisdictions, we know what plan checkers in each city look for.
- Design with the current code. Every plan set is prepared to the 2025 California codes and the local ADU rules of your city.
- Title 24 and CALGreen handled in-house. Your CF1R and energy calculations are prepared to match the drawings, so the most common consistency corrections never happen.
- Cross-sheet quality checks before submittal. Our AI-assisted review compares the site plan, floor plan, sections and energy report against California code requirements, so issues are fixed before the city sees them.
- Corrections handled for you. If the city does issue comments, we revise the drawings and prepare the response letter.
What a pre-submission check does not replace
A pre-submission check is a quality step. It does not replace the official review by the building department or local requirements unique to your jurisdiction. The goal is simple: submit a set that is as close to approval-ready as possible, the first time.
Frequently asked questions
How long does ADU plan check take in California?
State law generally requires cities to approve or deny a complete ADU application within 60 days. In practice, total time depends on how many correction rounds are needed. A complete, consistent first submission is the biggest factor you control.
What is the most common reason an ADU permit gets sent back?
Missing or inconsistent information across sheets is the most frequent issue. Examples include energy report values that don't match the drawings, undimensioned setbacks, and missing egress, stair or alarm details.
What codes apply to a California ADU in 2026?
ADUs must meet the 2025 California Building Standards Code, in effect since January 1, 2026. That includes the California Residential Code, Energy Code, CALGreen, and Electrical, Plumbing and Mechanical codes, plus state ADU law and local zoning.
Do ADUs need Title 24 energy compliance?
Yes. New ADUs and additions need a Title 24 energy compliance report, typically a CF1R, and the values in it must match the drawings. Newly constructed detached ADUs are generally subject to solar PV requirements, with some exceptions.
What are CALGreen requirements for an ADU?
CALGreen residential mandatory measures cover items like EV charging readiness, water-conserving plumbing fixtures, construction waste diversion and indoor air quality. They must be shown or noted on the plans.
Can AI check building plans for code compliance?
Yes. AI-assisted review can check a permit set against code rules, flag likely failures and missing information, and point to the sheet and code section involved. It is used before submission and does not replace official review.
How do I respond to plan check comments?
Revise the drawings, then submit a response letter that lists each comment, what you changed, and the sheet where the change appears. Cloud the revisions on the drawings so the reviewer can find them quickly.
Get your ADU approved on the first submission
Most ADU plan check corrections are predictable and preventable. Current code editions, dimensioned life-safety details, a matching Title 24 report and complete CALGreen notes remove the majority of reasons a set gets sent back.
Planning an ADU in the Bay Area? zHeight designs permit-ready plans with Title 24 and code compliance built in.
This article is for general information and is not legal or professional advice. Code requirements vary by jurisdiction, so confirm details with your local building department.