One of the first questions every Los Angeles homeowner asks when considering an ADU is: how long will this actually take? The honest answer is that a complete ADU project — from first conversation to move-in-ready unit — typically takes 9 to 18 months in Greater Los Angeles. The wide range reflects the type of ADU, the permit jurisdiction, contractor preparation, and whether unforeseen conditions arise during construction. APLA Construction (CA Lic #1136359) has built ADUs across all of Greater LA and this guide is based on what we actually see on the ground.
Every ADU project in Los Angeles moves through five distinct phases. Understanding each one will help you set realistic expectations and avoid surprises.
Before any drawings are made, a qualified ADU contractor needs to evaluate your property. This includes:
APLA provides this evaluation at no charge. Most homeowners can get a clear picture of what is and is not feasible on their property within one site visit.
Once the project scope is confirmed, your architect or designer prepares the plans. For a garage conversion ADU, this is relatively straightforward — the structure already exists and the drawings primarily cover the interior conversion. For a detached new-construction ADU, the design phase is more involved and includes:
Standard ADU designs by experienced architects typically take 4–6 weeks. More complex or custom designs can take 6–8 weeks.
This is the phase with the most variability in Greater Los Angeles. Permit timelines depend on which jurisdiction your property falls under:
Note: These are business processing timelines, not calendar days. Incomplete submittals that generate correction comments from the plan checker will reset the clock.
Once permits are issued, construction begins. Here is what the construction timeline looks like for each ADU type:
Before your ADU can be legally occupied, it must pass final inspection and receive a Certificate of Occupancy (CO) from the building department. This is typically a 1–2 week process once all work is complete and the inspection is scheduled. A contractor with a clean relationship with local inspectors and a tightly managed punch list process will move through this phase quickly.
Most delays are predictable and preventable with the right contractor. The most common causes of ADU delays in LA:
APLA manages the full ADU process from design coordination through final inspection under one contract. We pre-schedule inspections, complete permit submittals correctly the first time, and assign a dedicated site supervisor to each project. Our clients in Sherman Oaks, Studio City, Culver City, and across Greater LA see consistent timelines that match our initial estimates.
For properties in the City of Los Angeles (LADBS jurisdiction), ADU permit approval takes 4–8 weeks when the submittal is complete and accurate. California law requires LADBS to process ADU applications within 60 days. Other cities in Greater LA — Pasadena, Glendale, Santa Monica — have their own timelines ranging from 6 to 14 weeks.
A garage conversion ADU is the fastest ADU type — typically 9–12 months from start to Certificate of Occupancy. The existing structure eliminates the foundation, framing, and roofing phases. A JADU (Junior ADU within the main home) can be even faster at 6–10 months since no new structure is created.
Yes. Submitting a complete, accurate permit package the first time eliminates correction rounds — which are the single biggest source of permit delays. Hiring an architect experienced with LADBS or your specific city’s building department dramatically reduces back-and-forth. APLA’s design team has an established track record with LADBS and multiple LA city building departments.
A garage conversion ADU takes 11–16 weeks to build after permits are issued. A detached new-construction ADU takes 17–24 weeks. These timelines assume a dedicated crew and no major unforeseen conditions.
There is no bad season to start in LA — the mild climate means construction can proceed year-round. However, starting permit submittal in early spring (February–March) means you are in the construction phase before summer heat and clear of the holiday slowdowns that affect permit offices in December.
APLA manages the complete ADU process under one contract: design coordination, permit submittal, construction, all inspections, and final Certificate of Occupancy. You do not need to separately hire an architect, engineer, or permit expediter — APLA coordinates all of it.
APLA Construction builds ADUs throughout Greater Los Angeles — from garage conversions in Sherman Oaks to detached ADUs in Culver City and Pasadena. Contact us for a free site evaluation and realistic timeline estimate for your property.
Call: (818) 818-4419
Email: info@aplaconstruction.com
CA General Contractor License #1136359
Serving all of Greater Los Angeles — San Fernando Valley, Westside, South Bay, Pasadena, and beyond. Learn more about our ADU construction services.