ADU Permitting Process

California's ADU permitting process is now streamlined, but that doesn't mean it's simple! This blog post walks you through all of the different steps.

Last updated 
January 28, 2023
ADU Permitting Process

ADU Permitting Process

The permitting process for ADUs is more streamlined than for most residential building projects, thanks to state legislation and local offices adapting to growing ADU popularity. However, it’s not as simple as you might think.

In this post, we’ll outline the steps of the permitting process, show you how to apply, and give an idea of how long it might take for your permits to be processed.

Permitting Steps

Step 1: Plan Submission & City Initial Review Process

Once your ADU plans and necessary documents are submitted, they are reviewed by a number of departments within your local jurisdiction. At this time, your application is assigned a Plan Checker. When the Plan Checker decides the application is complete*, your fees** will be due.

After the plans have been fully reviewed, they are returned with comments and required clearances.

When you work with Otto to build your ADU, Otto pays the fees to keep momentum on the project and then provides you with an invoice and receipts.

*Complete vs. Approved

In this context, “complete” means that all of the necessary documentation has been provided and the Plan Checker is ready to begin the review process. It does not mean that the permit application is approved, and the Plan Checker may require changes to the plans before final approval is given.

**A note on ADU permit fees

Permit fees are calculated based on the type of work being done and the “valuation” of the work that you provide to the city. For standard garage conversion ADUs, fees between $2500-3500 is typical in LA City, LA County, Pasadena, South Pasadena, and other similar jurisdictions. Some jurisdictions—like Glendale—can easily charge twice that amount.

Step 2: Response & Resubmission

Once we’ve received the comments, our team reviews and responds to each comment and provides the required minor changes or clarifications. On rare occasions, the city may require modification of your project’s design; if that happens, we will notify you of the required alteration and our options for responding.

Simultaneously, our Permitting team gets to work on coordinating the required clearances from the Bureau of Engineering, Planning Department, Utility Agencies, and other city/county agencies that the Plan Checker requires to approve the permit set. Each clearance requires a varying level of documentation and review.

Clearance Examples

  • The Bureau of Engineering could assign clearances for sewer capacity and your ADU’s new address
  • The Planning Department could review your site plan to make sure you aren’t harming any protected trees
  • The Water Provider must give you “Will Serve” and “Fire Flow” letters affirming that your ADU will receive sufficient water (for ground-up ADUs, the Water Provider may also require a separate water connection directly from the street to the unit as a condition of providing these letters)
  • The Power Provider helps with any issues regarding construction near power lines or electrical service modifications
  • In LA City, an HPOZ (Historic Preservation Overlay Zone) is able to issue feedback regarding the design of your ADU
  • In LA City, the Bureau of Sanitation can assign Low Impact Development (LID) clearance to indicate your project is adequately managing stormwater

Step 3: Plan Checker Reviews Resubmission

After the resubmission, it is not uncommon for the Plan Checker to identify additional comments. They are usually minor and can be resubmitted and resolved within a week. Due to our extensive experience, most Otto conversion projects skip this intermediate step, but it is ultimately up to the Plan Checker and project details.

Step 4: City Final Review Process

When the Plan Checker deems the application approved, they mark it as Ready to Issue. Once this happens, Otto contacts the General Contractors (GCs) within our network and provides a final bid. Once the bid is accepted, we coordinate pulling the permit with the city.

At this point, the city requests insurance information from our selected GC and final permitting fees before issuing their stamp of approval. Then construction begins!

In-Person vs. Online Permit Submission

Depending on your jurisdiction, your permit application will either be submitted in person at a local office or online.

In-Person Permit Submission

Some jurisdictions are still managing applications exclusively via in-person communication.

In these circumstances, we print and submit construction plans, which each department then marks up and leaves their comments.

When the departments alert you that they have made comments, you’ll go to the office to pick up the set. Once all comments are addressed, you drop the plans back off and the process continues.

Online Permit Submission

The City of Los Angeles and a few other areas allow virtual correspondence, which makes the process easier to document and (typically) much swifter. ADU permit applications in LA City may be submitted via LADBS.

Permit Timelines

The speed at which your application is processed depends entirely on your jurisdiction.

Los Angeles

In our experience, LA City is the fastest:

  • Average turnaround for a garage conversion is 6 weeks from submission
  • Ground-up ADUs take a bit longer: 30 days to get a Plan Checker assigned, then 6+ weeks for approval

There are a few circumstances that can add review time to LA City projects, including:

Historic Preservation Overlay Zone

If your property is located in an HPOZ, your review time will take longer. The added time and fees depend on the amount of demolition involved in the project.If you aren’t doing substantial demolition*, the process falls under ministerial review/approval and is relatively straightforward. The HPOZ timeline is 21 days from when application is complete (submitting drawings, payment of HPOZ fees (approx. $700-1200), etc.). Anecdotally, we have heard that if an HPOZ takes over 21 days to complete a ministerial review, they must automatically approve. *HPOZs in LA have their own definition of “demolition”:  removal of >50% of wall framing, >50% of roof framing, or substantial removal of street-facing facade (see the LA municipal code 12.20.3.B.9 HP Overlay Zone definition of Demolition). If you are demolishing something, you will need to get board approval, which will cause delays to your process. Boards are supposed to meet monthly, but if not enough board members are available, the meeting is cancelled. Thankfully, we have also heard that if an HPOZ board takes over 21 days to review an application, they must automatically approve it.

Methane testing

The City of Los Angeles may require methane testing before approving permits. If the results of the test are not satisfactory, mitigation efforts are required before final approval may be issued, which can prolong the permitting process.


LA City also has special requirements for properties located within designated hillside areas, and meeting and reviewing these requirements can cause longer-than-average permit approval times.

Other Jurisdictions in Los Angeles County

Other jurisdictions take longer to process ADU permit applications. Average timelines range from 3 to 8 months (or more), depending on the jurisdiction.

Some jurisdictions with longer processing times include:

  • Burbank
  • Glendale
  • Pasadena
  • South Pasadena
  • Unincorporated LA County
  • Santa Monica

Regardless of the jurisdiction, unexpected delays sometimes pop up and slow the process down.


Despite recent changes in state law to easier facilitate ADU permitting, the process is still rather involved. If you don’t have the time or building design experience to communicate with various city departments and alter design plans, the process can seem overwhelming. But Otto can help!

Otto is very familiar with the permitting process in several jurisdictions across the Los Angeles area. We’ve designed and managed permitting for dozens of accessory dwelling units, and our expertise helps the process move much quicker than it often does for homeowner or GC-led projects.

If you’d like to get started designing and permitting your perfect ADU, contact Otto.

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