Design-Build ADU Builders for Standard and Non-Standard LA Lots
Most ADU construction in Los Angeles gets sold out of a catalog. Pick a floor plan, sign, wait. On a flat rectangular lot with an easy sewer connection, that works fine. It works a lot less well on a hillside, on an SB9 split, on a lot with a difficult soil report, or anywhere the drawings have to be defended in front of a plan checker. YD Group is a design-build firm with architecture, structural engineering and LADBS permit expediting under one roof, so the set that goes into plan check is the set we have to build.
Why LA Timelines Slip, and What the 60-Day Rule Actually Says
California law gives a local agency 60 days to approve or deny a complete ADU application (Government Code section 66317), and 15 business days to tell you whether the application is complete at all. Read that quickly and it sounds like a two-month permit.
The clock only runs on a complete application. Every time the city issues a correction letter, the submittal stops being complete, and the 60 days start over when you resubmit. That is how a 60-day statute and a real Los Angeles permit timeline of four to eight months before breaking ground manage to coexist. Two or three correction rounds are normal on most projects, including straightforward garage conversions, and separate clearances like LADWP and Fire usually add another two months.
So the number that decides your schedule is not the statutory 60 days. It is how many correction rounds your drawing set generates, and that depends on who prepared it. An ADU architect and a structural engineer working in the same office can control that. A pre-drawn plan cannot.
What California Law Guarantees You Can Build
State ADU law sets floors that no city in Los Angeles County can legislate below. As of 2026, under Government Code section 66323 and related statute, a local agency may not:
- Cap an ADU below 850 square feet, or below 1,000 square feet where the unit has more than one bedroom.
- Require more than four feet of side or rear setback for a newly constructed detached ADU.
- Require more than one parking space per unit, and it may require no parking at all within half a mile of public transit.
- Limit an existing multifamily property to fewer than eight detached ADUs, capped at the number of existing units on the lot.
A junior ADU is its own category, limited to 500 square feet, with one allowed per single-family lot.
Those are statewide minimums, not the whole picture. Hillside ordinances, very high fire hazard severity zones, historic overlays, easements and utility capacity all sit on top of them, and in Los Angeles they are usually what actually decides the project.
Detached New Construction
A standalone backyard unit with its own entrance, drawn to your lot rather than to a catalog. We settle the setback, height and utility routing questions on paper, where changes cost drawings instead of concrete.
Garage Conversion
Converting an existing garage looks like the easy option and often is not. Foundations, slab condition, headroom and fire separation from the primary residence are where these projects collect corrections. Compare the two approaches.
Hillside, SB9 and Multi-Unit Sites
Retaining walls, caissons and grade beams, geotechnical coordination, SB9 lot splits and multi-unit developments. A prefab model or a stock plan set cannot absorb this work, and it makes up a large share of our portfolio.
Choosing an ADU Contractor in Los Angeles
Most homeowners build an ADU team in pieces. A designer, then an engineer, then a permit runner, then a general contractor. Every handoff between them is a place where responsibility turns negotiable. When a plan checker rejects a detail, the designer says the engineer specified it, the engineer says the contractor asked for it, and the correction round happens anyway.
YD Group keeps architectural design, structural engineering, Title 24 energy calculations and LADBS submittal in the same office. One team answers for whether the set clears plan check, and the same team stands behind the build. On a standard lot that mostly saves time. On a hillside, a constrained lot or an SB9 site, it is often the difference between a project that gets permitted and one that stalls.
Related reading: LADBS ADU permit requirements, hillside ADU construction and what an ADU costs to build in Los Angeles, plus whether an ADU or a room addition adds more value.
Frequently Asked Questions (FAQ)
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How long does ADU construction in Los Angeles take?
Plan for four to eight months from starting drawings to breaking ground, plus the construction period after that. California law gives the agency 60 days to decide a complete application, but each correction letter restarts that clock, and most projects go through two or three rounds. Timelines vary a lot by lot and by jurisdiction. -
Do I need an architect, an engineer, or a contractor to build an ADU?
In practice you need all three. Los Angeles wants stamped structural drawings and Title 24 energy calculations before it issues a permit, and a licensed contractor to build to them. With a design-build firm, one contract covers the whole sequence instead of three that point at each other. -
How large can my ADU be?
Under current state law a city cannot hold an ADU below 850 square feet, or below 1,000 square feet if it has more than one bedroom. What your specific lot supports comes down to setbacks, lot coverage, height limits and any overlay zones that apply to it. -
Can I build an ADU on a hillside lot?
Usually yes, but hillside lots bring retaining walls, grading limits, geotechnical reports, deep foundations and access requirements that flat-lot plan sets never address. Pre-drawn and prefab ADU packages rarely work here without substantial custom engineering. -
Do ADU builders handle the permit process?
Some do. Others leave it to you or to a third-party expediter. We prepare the drawing set, submit it, and manage corrections through to permit issuance, because how a set is drawn is what decides how many correction rounds it draws. -
What is the difference between an ADU and a JADU?
A JADU tops out at 500 square feet, has to be created within the walls of an existing single-family home, and only one is allowed per lot. A standard ADU can be detached, attached or converted, and it is far less constrained in size.
The requirements and timelines described here reflect California state law and typical Los Angeles market conditions as of 2026, and are offered as general guidance. Your zone, lot conditions, overlays and utility capacity decide what is actually buildable, and an accurate answer for your property comes from a feasibility review.
Approved by the City of Los Angeles
Three of our ADU designs are on the LADBS Standard Plan Program list, which means the City of Los Angeles has already reviewed and approved the drawings. Building from a standard plan takes design review off your schedule completely. The plan check that normally runs for months has already happened.
- ADU83: 1 story, 1 bedroom with options, 743 sq ft
- ADU80: 1 story, 2 bedrooms with options, 900 sq ft
- ADU75: 2 story, 3 bedrooms with options, 1,180 sq ft
All three appear on the LADBS approved standard plans register under our practice, with YD Group as applicant, designer and structural engineer of record.
Find Out What Your Lot Will Actually Support
Before you commit to a floor plan, get a feasibility review of your property: zoning, setbacks, utilities and the constraints that decide the schedule. Contact YD Group to book yours.
