How Long Does It Take To Get an ADU Permit in Los Angeles?

Getting an ADU permit in Los Angeles County used to mean waiting years, not months, for approval, but that's changing fast.

An analysis of more than 14,700 ADU permits with documented processing timelines, filed across LA County between 2018 and early 2026, reveals that the median time to approve an ADU permit has dropped 80% in four years, from 942 days in 2021 to just 191 days in 2025.

For homeowners wondering, "how long does an ADU permit take in Los Angeles?", the answer today is dramatically different from what it was even two years ago.

All data referenced in this article is drawn from LA County public permitting records and is available in full at stats.ladu.co.

If you've been thinking of building an ADU, now is the time to act. Request a free site visit from LADU today.

We specialize in building ADUs in the Los Angeles area and have streamlined the process with full ADU design services, ADU permitting, and ADU construction partners, all managed by one team.

Building an ADU has never been easier. Call (213) 855-3334 to learn more about our services.

ADUs Designed Better. Built Smarter.

ADU Permit Processing Times in Los Angeles: Year-by-Year Breakdown

LA County's ADU permitting process was defined by extreme wait times for years. The data shows a steady climb in processing duration from 2018 through 2021, followed by a sustained and accelerating decline:

The climb (2018–2021):

• 2018: 495 days median (approximately 1.4 years)
• 2019: 656 days median (approximately 1.8 years)
• 2020: 822 days median (approximately 2.3 years)
• 2021: 942 days median (approximately 2.6 years)

At the peak, a homeowner submitting an ADU permit application in 2021 would typically not receive approval until mid-2024. The slowest cases in the dataset stretched beyond 2,900 days, roughly eight years from application to resolution.

The turnaround (2022–2026):

• 2022: 791 days median (down 16% from peak)
• 2023: 618 days median (down 22%)
• 2024: 456 days median (down 26%)
• 2025: 191 days median (down 58%)
• 2026 (early data): 63 days median*

*The 2026 figure reflects permits filed in the first months of the year and may shift as newer applications move through the system.

The improvement tracks with state and local reforms designed to streamline ADU permitting, including simplified review processes, pre-approved plan programs, and legislative mandates requiring faster turnaround from planning departments.

Why ADU Permit Wait Times Varied So Much

Several factors contributed to the years-long processing times that defined the 2018–2021 period:

• Surging demand: ADU permit applications in LA County nearly tripled between 2018 and 2025, overwhelming planning departments that weren't staffed for the volume.
• Complex review processes: Many jurisdictions required multiple rounds of plan check corrections, each adding weeks or months.
• Inconsistent standards: Requirements varied across the county's 35+ cities, creating bottlenecks at some offices while others processed more efficiently.
• COVID-era disruptions: Office closures and staffing shortages in 2020 contributed to the backlog that took years to clear.

The Backlog Still Shapes the Data

Despite the improvement in processing times for new applications, the historical backlog continues to affect the overall picture. Looking at all permits with processing data in the dataset:

• 29.2% of permits (4,292) took between one and two years to process
• 14.5% (2,137) took between two and three years
• 10.9% (1,598) took between three and five years
• 6.0% (887) took more than five years
• Only 18.5% of all ADU permits in the dataset were processed in under six months

These numbers reflect the full 2018–2026 period. Homeowners filing today can expect significantly shorter timelines, but the backlog data is a reminder of how recently the system was in much worse shape.

ADU Permit Timeline by City: Where You Apply Matters

Processing speed varies dramatically by jurisdiction within LA County. Among cities with significant permit volume:

Fastest ADU Permit Processing

City	Median Processing Time	Permits Tracked
Altadena	188 days	2,465
Compton	417 days	390
Arcadia	453 days	325

Slowest ADU Permit Processing

City	Median Processing Time	Permits Tracked
Los Angeles (city)	610 days	3,291
Castaic	712 days	58
Littlerock	700 days	107

Altadena processes ADU permits more than three times faster than Los Angeles proper, which is a gap that persists even when controlling for permit volume.

For homeowners deciding where to build, this data matters: the jurisdiction you apply in can add or subtract months (or years) from your timeline. The full city-by-city breakdown is available at stats.ladu.co. Use LADU's property lookup tool to see if your property qualifies.

What This Means for Homeowners Planning an ADU

The 80% reduction in ADU permit processing times is more than a bureaucratic improvement. Permitting speed is the single biggest factor that determines whether a homeowner follows through on building an ADU and how long it will take.

Years-long waits discouraged thousands of potential projects. With median wait times now under six months and trending lower, the calculus has fundamentally changed.

If you're considering an ADU in Los Angeles County, here's what the data suggests:

1. Start now. Processing times are at their lowest in the dataset's history and may continue improving, but demand is also rising.
2. Check your jurisdiction. The city you build in can dramatically affect your timeline. Research processing times for your specific area.
3. Prepare complete applications. Incomplete submissions are the most common cause of delays. Working with experienced professionals helps avoid costly resubmissions.
4. Consider pre-approved plans. Several LA County jurisdictions now offer pre-approved ADU plans that can cut weeks or months from the review process.

How LADU Helps Navigate the ADU Permitting Process

At LADU, we handle the entire ADU process from architectural design through permitting and ADU construction arrangements.

Our team has guided hundreds of homeowners through LA County's permitting system, and we use data, including the permit records behind this analysis, to set realistic timelines and help homeowners avoid common delays.

Our architect-led, vertically integrated approach means fewer handoffs, fewer errors, and faster approvals.

Schedule a free consultation to learn how LADU can help you navigate the ADU permitting process and get your project moving.

Full Data Available

All data cited in this article is sourced from LA County public permitting records and published at stats.ladu.co. The dataset includes permit-level processing timelines, year-over-year trends, and jurisdiction-level breakdowns. It's freely available for research and reporting.