9 to 18 months for most projects — and construction is often the shortest phase.
How Long Does an ADU Take to Build in Los Angeles? Realistic Timelines by Type
Design, engineering, and plan check can add five to eight months to the front of an ADU project before a single tool touches the site. Here’s what each phase actually takes, by ADU type.
CSLB #1071589Licensed Since 2020LA DBS & LA County DPW
Answer First
A Los Angeles ADU Takes Longer Than the Construction Phase Alone
The full ADU timeline in Los Angeles runs 9 to 18 months for most projects — and construction is often the shortest phase.
Most homeowners planning an ADU focus on the build — crews, materials, a finished unit. What they don’t account for is everything that happens before a permit is issued. In Los Angeles, the design, engineering, and plan check phases can add five to eight months to the front of a project. Planning your timeline around move-in dates or rental income requires knowing what all the phases actually take, not just the construction window.
9–18 mo
Typical full ADU timeline
3–5 mo
Plan check, detached new build
6–8 wks
Added per correction cycle
4–8 wks
LADWP connection at the end
In this guide
Local Context
Why Los Angeles ADU Timelines Run Longer Than Other Markets
LA DBS plan check timelines and LADWP scheduling add phases that most homeowners don’t see coming.
Los Angeles has one of the most active ADU permit pipelines in the country, and that volume affects review speed at LA DBS — the city agency that issues building permits and conducts construction inspections. Standard plan check reviews for new detached ADU construction currently run three to five months. Conversion projects typically move faster, averaging six to ten weeks, but only when the application is complete and accurate on first submission.
A correction request — a written response from LA DBS identifying items that must be revised before the permit can be issued — restarts a portion of the review clock. One correction cycle on a detached ADU application can add six to eight weeks. Two cycles can push permit issuance past the six-month mark from initial submission.
LADWP — the Los Angeles Department of Water and Power — adds another layer at the end. Electrical service connection for a new ADU typically requires four to eight weeks of scheduling after construction is complete, independent of LA DBS and on LADWP’s own calendar. Projects in unincorporated LA County route through LA County DPW instead, whose review timelines differ from city timelines.
By Phase
ADU Timeline by Phase: What Each Stage Actually Takes
Every ADU project moves through the same sequence — design, permit application, plan check, issuance, construction, inspections, and utility connection.
Design and Engineering Phase
The period before anything is submitted to LA DBS. An architect or designer produces architectural drawings, structural calculations, the Title 24 energy compliance report, and the site plan — the documents that form the permit application package. Duration: 4 to 8 weeks for most ADU types. Above-garage ADUs run closer to 8 to 10 weeks because the structural calculations for the existing garage carrying new load above are more involved.
A complete, accurate application package submitted on the first attempt is the single most effective way to reduce the overall project timeline.
LA DBS Plan Check Timeline
ADU Type
Plan Check (first submission, clean)
JADU (within existing structure)
4 to 6 weeks
Garage Conversion
6 to 10 weeks
Attached ADU
8 to 14 weeks
Detached ADU (new construction)
3 to 5 months
Above-Garage ADU
4 to 6 months
Projects that qualify for SB 35 ministerial approval — a streamlined, non-discretionary process available for certain affordable housing projects — can move significantly faster, since LA DBS must approve them administratively without discretionary review. Not every ADU qualifies, but the pathway is worth evaluating.
Permit Issuance
After plan check clears with no outstanding corrections, the permit is issued and construction can begin — typically one to two weeks after final plan check approval, less if the applicant responds to issuance notices quickly.
Construction Phase by ADU Type
ADU Type
Construction Duration
JADU Conversion
6 to 8 weeks
Garage Conversion
8 to 12 weeks
Attached ADU
12 to 16 weeks
Detached ADU (new build)
14 to 20 weeks
Above-Garage ADU
16 to 24 weeks
Construction begins the day the permit is in hand and ends when all inspections pass — foundation, framing, MEP rough-in, insulation, drywall, finishes, and final inspection. Above-garage ADUs carry the longest window because the existing garage structure must be reinforced before the new unit above can be framed.
LADWP Utility Connection Schedule
After construction is complete and the final LA DBS inspection is signed off, electrical service connection with LADWP is scheduled — typically four to eight weeks. This is not a construction delay; it’s an external scheduling dependency that adds time at the project’s end.
Total Timeline by ADU Type (Design Through Move-In)
ADU Type
Total Estimated Timeline
JADU
5 to 8 months
Garage Conversion
6 to 10 months
Attached ADU
9 to 14 months
Detached ADU (new build)
12 to 18 months
Above-Garage ADU
14 to 20 months
These ranges assume a clean first submission with no correction requests. Each correction cycle adds six to eight weeks to the plan check phase.
Scenarios
Three Los Angeles ADU Scenarios and How Timelines Play Out
The same ADU type can have very different timelines depending on the property, the jurisdiction, and the application quality.
Garage conversion in the San Fernando Valley
A homeowner in Reseda plans a 450-square-foot garage conversion inside the City of LA, so the application goes to LA DBS. Design takes five weeks. Plan check takes eight weeks on a clean first submission. Permit issues within ten days. Construction runs ten weeks, and LADWP connection takes five weeks after final inspection. Total: roughly seven months from first design meeting to move-in.
Detached ADU with one correction cycle
A homeowner in Granada Hills submits plans for a 750-square-foot detached ADU. Design takes six weeks. LA DBS issues a correction request after twelve weeks of plan check — one item on the structural calculations — reviewed in another seven weeks. Permit issues two weeks later, construction runs sixteen weeks, LADWP takes six. Total: roughly fourteen months, with the correction cycle alone adding seven weeks.
JADU conversion in unincorporated LA County
A homeowner near Altadena plans a 480-square-foot JADU inside the main home’s existing footprint. Because the parcel is unincorporated, the application routes through LA County DPW rather than LA DBS. Design takes four weeks, plan check nine weeks, construction seven weeks, LADWP four. Total: roughly six months — but the routing affected both submission requirements and review timeline.
Professional Perspective
What I’ve Seen in Four Years of LA ADU Projects
— Uzi Ezra, Founder & CEO, US LA Home Remodeling Inc
The gap between expected and actual timelines almost always lives in the permit phase — and planning for it upfront changes the whole project experience.
When I started US LA Home Remodeling Inc in 2020, I watched homeowners plan rental income start dates around construction timelines alone. They’d hear “fourteen weeks to build” and back-calculate a lease start date from there. What wasn’t in that math was the four to five months of design and plan check sitting in front of the build.
The construction phase is the part I control completely — I can sequence trades, order materials ahead of inspections, and keep a crew on schedule. The plan check timeline is something different. I can influence it, and a complete, accurate first submission is the most powerful thing I do to protect a homeowner’s schedule, but I can’t compress LA DBS’s review queue.
What I tell every client before we start: build the timeline from first design meeting to LADWP connection. That’s the real schedule. Rental income, family occupancy, refinancing against the ADU’s value — all of those depend on the full timeline, not just the construction window.
When to Call
When to Bring a Licensed Contractor Into the Timeline Conversation
The design phase is the right time to involve a licensed contractor — not after plans are drawn.
Bringing a licensed contractor in before design begins has a direct effect on the plan check phase. A contractor with active LA DBS experience knows which drawing details trigger correction requests and which material specifications cause reviewers to flag structural questions. That knowledge shapes the application package before it’s submitted.
If you’re evaluating an ADU project, the most useful thing a contractor can tell you at that stage isn’t a construction price — it’s a realistic end-to-end schedule, including which phases they control and which depend on external agency timelines. See the ADU builder program for how feasibility, design, and construction fit together.
A contractor who can map that schedule from design through LADWP connection — with phase-specific duration ranges by ADU type — is working from direct project experience. That experience is worth more than a rough construction estimate at the outset.
Areas We Serve
ADU Projects Across Greater Los Angeles
US LA Home Remodeling Inc manages ADU construction across the full Greater Los Angeles area — from the San Fernando Valley, including Tarzana, Reseda, Granada Hills, Woodland Hills, and Northridge, to communities throughout the City of Los Angeles and surrounding LA County. We file permits through both LA DBS and LA County DPW. Office and dispatch: 5530 Corbin Ave, Tarzana, CA 91356.
TarzanaResedaGranada HillsWoodland HillsNorthridgeCity of Los AngelesAltadenaLA County
Ready to Start?
Start With the Full Timeline, Not Just the Build
Every ADU project needs a schedule that runs from first design meeting to LADWP connection — not just from permit issuance to construction completion. The first conversation covers your ADU type, your property’s jurisdiction, and what the full timeline looks like for your specific project.
1-800-508-0259 · info@uslaremodeling.com · 5530 Corbin Ave, Tarzana, CA 91356