What Revisions Kill ADU Permit Timelines?

Why ADU Permit Revisions Derail Your Timeline

If you are planning to build an Accessory Dwelling Unit in California, one of the biggest risks to your timeline is permit revisions. The California Department of Housing and Community Development (HCD) mandates that local jurisdictions process ADU permits within 60 days of a complete application. But that 60-day clock only starts when your application is deemed "complete," and it resets every time the city issues a correction letter asking for revisions to your plans.

For many homeowners in Los Angeles and across California, what they expected to be a two-month permitting process turns into a six-month or even year-long ordeal. Each round of revisions can add 4 to 8 weeks to your project, and some projects go through three, four, or even five rounds of corrections before finally receiving approval.

In this comprehensive guide, we will walk through the most common revisions that kill ADU permit timelines, explain exactly why each one happens, and give you actionable strategies to avoid them. Whether you are working with an architect, a design-build firm, or planning to submit plans yourself, understanding these pitfalls will save you thousands of dollars and months of frustration.

How the ADU Plan Check Revision Process Works

Before diving into specific revisions, it helps to understand how the revision cycle works in most California cities. When you submit your ADU plans to the building department, the plans are routed to multiple review desks. In Los Angeles, for example, your plans may be reviewed by the building and safety division, the fire department, the department of city planning, the bureau of engineering, and sometimes the department of water and power.

Each desk reviews your plans independently and generates a list of corrections. These corrections are compiled into a single correction letter (sometimes called a "plan check letter" or "clearance sheet") and sent back to you or your architect. You then have to address every single correction, resubmit your plans, and wait for them to be re-reviewed.

Here is where timelines get destroyed: each re-review typically takes 2 to 4 weeks, and if any single desk finds additional issues or your corrections did not fully address their concerns, you receive another correction letter. This cycle can repeat multiple times.

Revision Cycle	Typical Wait Time	Cumulative Delay
First plan check	4-6 weeks	4-6 weeks
First revision re-review	2-4 weeks	6-10 weeks
Second revision re-review	2-4 weeks	8-14 weeks
Third revision re-review	2-4 weeks	10-18 weeks

As you can see, three rounds of revisions can stretch a process that should take 60 days into 4 or 5 months. And this does not even count the time your architect needs to actually make the corrections and prepare revised plans, which can take 1 to 2 weeks per cycle.

The Top 10 Revisions That Kill ADU Permit Timelines

1. Incomplete or Missing Structural Calculations

Structural calculations (also called "calcs") are required for virtually every ADU project in California. These calculations demonstrate that your ADU's foundation, framing, and roof structure meet the requirements of the California Building Code (CBC). One of the most frequent revision requests is for missing, incomplete, or inconsistent structural calculations.

Common issues include calculations that do not match what is shown on the plans, missing lateral force analysis for seismic loads, missing foundation calculations, or failing to account for California's seismic design requirements. If your structural engineer uses generic calculations rather than site-specific ones, the plan checker will send them back for revision.

To avoid this, hire a licensed California structural engineer (not just a designer) and have them coordinate directly with your architect before submittal. Verify that all beam sizes, foundation details, and connection hardware on the plans exactly match what is in the calculation package.

2. Title 24 Energy Compliance Errors

California's Title 24 energy standards are strict, and ADUs are no exception. The energy compliance report (CF-1R for residential) must be submitted with your plans and must be consistent with what is actually shown on the construction documents. Frequent revision triggers include window specifications that do not match the Title 24 report, incorrect climate zone assignments, missing mechanical ventilation details, and HVAC equipment that does not meet minimum efficiency requirements.

The California Energy Commission updates these standards regularly. In 2026, heat pump systems are the baseline for new construction, and your plans must show compliant equipment. If your HVAC system does not match your Title 24 report, expect a correction letter.

3. Setback and Zoning Violations

California state law (Government Code Section 65852.2) establishes maximum setback requirements for ADUs. For detached ADUs, the state law allows a maximum 4-foot rear and side setback requirement. However, many homeowners and even some designers make mistakes here. Common setback-related revisions include measuring setbacks incorrectly (from the wrong reference point), not accounting for roof overhangs, violations of front yard setback requirements (which are not reduced by state law), and encroachment into utility easements.

The solution is to obtain a current survey of your property and verify all setback dimensions before submittal. Have your designer clearly call out all setback dimensions on the site plan.

4. Fire Separation Distance Issues

When your ADU is close to the property line or to the main house, the California Building Code and California Residential Code impose specific requirements for fire separation distance. These requirements affect wall construction, window placement, and roof assembly. If your ADU wall is less than 5 feet from a property line, you may need a 1-hour fire-rated wall assembly with no openings (windows or doors) on that side.

This is one of the most common revision triggers because designers sometimes show windows on walls that are too close to property lines, or they fail to specify the proper fire-rated wall assembly. Your plans should clearly indicate all fire-rated assemblies with UL or GA numbers.

5. Grading and Drainage Plan Deficiencies

Most jurisdictions require a grading and drainage plan that shows how stormwater will be managed on your property after the ADU is built. Common revision triggers include failing to show drainage away from foundations, missing stormwater management calculations, not showing existing and proposed drainage patterns, and conflicting grades between the site plan and the grading plan.

In Los Angeles, the Bureau of Engineering reviews grading plans separately from the building plans. This means your grading corrections can hold up your entire project even if your building plans are approved. Work with a civil engineer to prepare a thorough grading plan from the start.

6. Utility Connection Discrepancies

Your ADU plans must clearly show how the unit will connect to water, sewer, gas (if applicable), and electrical service. Many correction letters cite missing or unclear utility connection details. Common issues include not showing the sewer lateral connection point, unclear electrical panel location and service size, missing water meter or sub-meter details, and gas line routing conflicts with other utilities.

Contact your local utility providers (LADWP, SoCal Gas, etc.) early in the design process to understand connection requirements. Show all utility connections clearly on your site plan and include a plumbing riser diagram.

7. Parking and Access Issues

While California state law has largely eliminated parking requirements for ADUs (especially those within half a mile of public transit), there are still situations where parking-related corrections arise. If your ADU project eliminates existing covered parking (such as converting a garage), you may need to show replacement uncovered parking spaces. Access issues, such as inadequate turning radius for emergency vehicles or blocked access to the main home, can also trigger revisions.

8. Missing or Incorrect Details on Construction Documents

Plan checkers are meticulous. Missing details that may seem minor can trigger a revision cycle. Common examples include missing window and door schedules, absent hardware specifications for structural connections (Simpson ties, hold-downs, etc.), incomplete electrical panel schedules, missing plumbing fixture counts, and insufficient roof ventilation details.

A thorough, complete set of construction documents is your best defense. Ask your architect to use a comprehensive ADU plan check list before submitting.

9. Americans with Disabilities Act (ADA) and Accessibility Issues

While ADUs are generally classified as residential and are not subject to full ADA requirements, certain accessibility provisions may apply depending on the jurisdiction and the intended use. If the ADU is intended for rental or if local ordinances require accessible features, you may need to show accessible pathways, doorway widths, and bathroom clearances. Missing or incorrect accessibility details are a growing source of revisions.

10. Inconsistencies Between Plan Sheets

One of the most frustrating reasons for revisions is simple inconsistency between different sheets of your plans. If the floor plan shows a 36-inch door but the elevation shows a 30-inch door, or if the site plan shows the ADU in a different location than the grading plan, the plan checker will flag it. These types of errors are entirely preventable with a careful quality check before submittal.

How Revisions Impact Your Overall Project Cost

Permit revisions do not just cost you time. They cost real money. Here is how:

Cost Category	Per Revision Cycle	3 Revision Cycles
Architect revision fees	$500 - $2,000	$1,500 - $6,000
Structural engineer revisions	$300 - $1,000	$900 - $3,000
Title 24 report updates	$200 - $500	$600 - $1,500
Construction cost escalation	$1,000 - $3,000+	$3,000 - $9,000+
Lost rental income	$2,000 - $4,000	$6,000 - $12,000

When you add it all up, three rounds of revisions can cost a homeowner $12,000 to $30,000 or more in direct costs and lost income. This is why investing in quality plans upfront is so critical.

Proven Strategies to Minimize Revisions

Based on our experience helping hundreds of homeowners through the ADU permitting process, here are the most effective strategies to minimize or eliminate revisions:

Hire an Experienced ADU-Specific Designer

Not all architects and designers are equal when it comes to ADU permitting. Look for a designer who has successfully permitted at least 20 ADUs in your specific city. They will know the local plan checker's preferences, common correction items, and how to address them proactively. Check out our guide on choosing the right ADU contractor for more tips.

Get a Pre-Submittal Meeting

Many building departments offer pre-submittal meetings or over-the-counter consultations where you can review preliminary plans with a plan checker before formal submittal. This is invaluable for identifying potential issues early. In Los Angeles, you can schedule a preliminary consultation with LADBS for a nominal fee.

Use a Plan Check Checklist

Before submitting, go through every item on your jurisdiction's plan check requirements list. Most building departments publish these on their websites. Compare your plans against the checklist item by item.

Coordinate All Consultants

Ensure your architect, structural engineer, Title 24 consultant, and civil engineer are all working from the same base plans and are coordinating their work. Many revisions stem from consultants working in silos.

Los Angeles-Specific Revision Triggers

If you are building an ADU in the City of Los Angeles, there are some city-specific issues that frequently cause revisions:

• Hillside Ordinance compliance: Properties in hillside areas face additional requirements for grading, retaining walls, and maximum building height calculations
• Specific Plan areas: Many neighborhoods in LA have specific plans with additional design requirements that go beyond standard zoning
• Historic districts: If your property is in a Historic Preservation Overlay Zone (HPOZ), your ADU design may need to comply with architectural guidelines
• Very High Fire Hazard Severity Zone (VHFHSZ): Properties in fire zones face additional requirements for exterior materials, sprinklers, and defensible space
• Green code compliance: LA Green Building Code (LAGBC) adds requirements for water conservation, materials, and energy efficiency

Understanding these LA-specific requirements before you start designing is essential. The LADBS website provides zoning information reports (ZIMAS) that will tell you which overlay zones and specific plans apply to your property.

How to Get Expedited Plan Review

Several California cities offer expedited or priority plan review for ADUs. In Los Angeles, LADBS offers an Express Plan Check program that can reduce initial review time to 15 business days. Other cities like Pasadena and Long Beach have similar programs. However, be aware that expedited review only speeds up the initial review, not subsequent revision cycles. The best way to take advantage of expedited review is to submit clean, complete plans that do not require revisions.

Some jurisdictions also offer over-the-counter approval for qualifying ADU projects, which can dramatically reduce your permitting timeline. See our detailed comparison of approval processes to determine if your project qualifies.

Frequently Asked Questions

How many revision cycles does the average ADU project go through?

The average ADU project in California goes through 1.5 to 2.5 revision cycles. Well-prepared plans from experienced designers may receive approval with zero or one revision. Poorly prepared plans can go through 4 or more cycles. According to data from the California HCD, projects submitted by experienced ADU designers have a 40% lower revision rate.

Does the 60-day permit processing clock reset with each revision?

Under California Government Code Section 65852.2, the 60-day clock begins when the application is deemed complete. When the city issues corrections, the clock pauses until you resubmit revised plans. Once you resubmit, the city has 60 days to review the revised plans. In practice, most cities process revisions faster than the initial review, but the total elapsed time still increases significantly.

Can I appeal a revision request that I disagree with?

Yes, you can request a meeting with the supervising plan checker or the chief building official to discuss a correction you believe is incorrect. This is especially relevant when a local requirement conflicts with California state ADU law, as state law generally preempts local regulations. Document your position with code references and bring them to the meeting.

Should I use a permit expediting service?

Permit expediting services can be helpful for navigating complex city processes, but they do not eliminate the need for quality plans. A good expediter can help you submit to the right desks, follow up on stalled reviews, and communicate with plan checkers. Expect to pay $1,500 to $5,000 for ADU expediting services in Los Angeles.

What happens if my contractor starts building before revisions are resolved?

Never begin construction without an approved permit. Building without a permit can result in stop-work orders, fines, and required demolition of completed work. The risks far outweigh any time savings. Wait for your approved plans before beginning construction. Learn more about the complete ADU permit process in our detailed guide.

How can I check the status of my plan review?

Most California cities now offer online plan check tracking. In Los Angeles, you can check your permit status through the LADBS online portal. You can also call your assigned plan checker directly. Keep your permit application number handy for all status inquiries.