ADU Contractor in Los Angeles
No two Los Angeles lots hand you the same ADU project. The city spans pre-war bungalow blocks with alley-fed detached garages, postwar Valley tracts, hillside parcels that need engineering before they need architecture, and Coastal Zone properties on a different approval track entirely.
What ADUs look like in Los Angeles
In the older flatland neighbourhoods — much of the Eastside, Mid-City, and the pre-war blocks of the Valley — the standard configuration is a single-storey house with a detached one- or two-car garage at the rear, often reached by a long driveway or an alley. That garage is the single most common ADU in Los Angeles, because the footprint, the setbacks and often the sewer connection already exist. Postwar Valley tracts tend to give you a larger, flatter rear yard, which usually favours a new detached unit over a conversion. Hillside parcels are a different project: the geotechnical report, the engineered footings and fire-zone construction can add six figures before the unit itself is priced, and they are the main reason two ADUs of the same size in the same city can differ by $150,000.
Roughly speaking: detached garage on a flat lot means start with a conversion; open flat rear yard means a new detached unit is usually better value per square foot; hillside means get the soils report before you fall in love with a floor plan.
Four ways to add an ADU in Los Angeles
Most cities give you three routes. The City of Los Angeles gives you a fourth, because it runs the deepest pre-approved plan catalogue in the region — including one plan it gives away.
| Route | Suits an LA lot when | The catch |
|---|---|---|
| Pre-approved standard plan | Level lot, ordinary soil, and one of the catalogue sizes genuinely fits what you need. The structural set has already been reviewed once by LADBS | You still submit your own zoning, setbacks and foundation. Layout freedom is limited or nil, and the free YOU-ADU set assumes level grade |
| Detached new build | You want the layout to suit the household rather than the catalogue, or the lot is anything other than straightforward | Full structural review, plus the solar requirement that comes with any new detached dwelling |
| Garage conversion | The pre-war flatland blocks — the Eastside, Mid-City, the older Valley streets — where a detached garage sits at the rear, often fed from an alley | You lose the garage, and an unpermitted one has to be legalised first. Alley access helps construction but can complicate the new services |
| Junior ADU inside the house | Hillside or Coastal parcels where building anything new outside is the expensive part | Capped at 500 square feet and it costs you a bedroom |
The standard-plan route is genuinely worth understanding before you commission a design — our guide to the LADBS ADU Standard Plan Program covers what it saves, what it does not, and the assumptions the free plan makes about your lot. Detached ADU vs garage conversion covers the other main trade.
What an ADU costs in Los Angeles
What moves a Los Angeles project inside our published ranges: Hillside lots are the biggest single swing: a geotechnical report, engineered footings and fire-zone construction. Coastal Zone properties need a Coastal Development Permit, which adds months rather than dollars, but the carrying cost is real. On older flatland lots, the two things that most often move a budget after demolition starts are the sewer lateral and the main electrical panel — both are invisible until someone opens them up, which is why we look at them on the site walk rather than after.
| ADU type | Typical all-in budget |
|---|---|
| Garage conversion | $100,000–$200,000 |
| Detached, about 500 sq ft | $180,000–$260,000 |
| Detached, 700–800 sq ft | $225,000–$350,000 |
| Detached, 1,000 sq ft | $300,000–$450,000+ |
These are typical Los Angeles budgeting estimates, not a price list or a quote. Your project can come in lower or higher depending on the house, the scope and the finishes; the only real number is a written proposal after a site visit.
Budgeting ranges, not quotes — see the full ADU cost breakdown.
How the permit process works in Los Angeles
Submittal goes to LADBS through ePlanLA. LADBS has 15 business days to confirm the application is complete, and every department must approve or deny within 60 days of that. The important structural point is that plan check runs alongside City Planning, Fire, LADWP and Sanitation clearances rather than after them, so the project moves at the speed of the slowest department. Before design starts we pull the zoning, Hillside Area, fire-zone, HPOZ and Coastal Zone flags from ZIMAS and confirm transit distance, because that combination decides whether you build a state-law ADU, an ordinance ADU, or both.
What we check on a Los Angeles lot first
- Zoning, Hillside Area, fire-zone, HPOZ and Coastal Zone flags pulled from ZIMAS
- Distance to a major transit stop, which decides 16 ft or 18 ft of height
- Whether a state-law ADU, an ordinance ADU, or both are available on the parcel
- Sewer lateral condition and main electrical panel capacity
That site walk is free, and it is deliberately where we tell people if a lot does not work.
How long a Los Angeles ADU takes, end to end
The structural fact about LA is that plan check runs alongside City Planning, Fire, LADWP and Sanitation rather than after them. That is faster than a queue — but it means the project moves at the speed of the slowest department, and one unanswered clearance holds everything.
| Phase | What happens | Typical |
|---|---|---|
| Feasibility | Site walk, zoning and overlay check, hillside or Coastal status, LADWP capacity, and whether a standard plan fits | 2–4 weeks |
| Design and engineering | Layout, structural, Title 24, solar. Shorter if a pre-approved plan fits your lot | 2–6 weeks |
| Plan check | ePlanLA submittal to LADBS — 15 business days to confirm completeness, then 60 days per department, running in parallel | 5–10 weeks |
| Construction | Garage conversion at the short end; hillside or Coastal work at the long end | 3–6 months |
| Inspections and close-out | Final sign-offs, LADWP connections, certificate of occupancy | 1–4 weeks |
Add the phases up and a detached unit runs roughly five to ten months from first conversation to keys, with a garage conversion at the short end. Los Angeles has the widest spread of any city we work in, because a flat Valley lot and a Coastal Zone hillside parcel are barely the same project. How long an ADU takes goes through the same phases in more detail.
LADWP, and why parallel clearances cut both ways
LADWP is a clearance in its own right, running at the same time as plan check rather than after it. When it is handled early that is an advantage — nothing waits in line. When it is not, it becomes the department everything else is waiting on, and the 60-day clocks keep running while nothing moves.
What we settle before design rather than during review:
- Electric service capacity. A second dwelling with its own kitchen, laundry, heat pump and required solar is real load. A great many older LA houses sit on a panel that will not carry it, and the upgrade is a real line item.
- Where the services actually run. Alley-fed properties in the pre-war neighbourhoods behave differently from street-fed ones, and it affects where the unit can sensibly go.
- Water service and metering. Shared or separate, decided at design stage — retrofitting a separate service later is the expensive version.
None of this is exotic. It is simply the difference between a project that clears in one cycle and one that spends an extra two months in correction letters.
Where we build
We build across the City of Los Angeles and the wider county, from the Valley through the Westside to the Eastside; our Los Angeles page lists the areas we cover, and we also work throughout the San Fernando Valley.
ADU questions Los Angeles homeowners ask us
Is a garage conversion cheaper than a detached ADU in Los Angeles?
Usually, yes. A garage conversion typically runs $100,000–$200,000 against $180,000–$260,000 for a detached 500 sq ft unit, because the slab, walls and roof already exist. The exception is a garage with a failing slab or no footings worth keeping, where the demolition and rebuild can cost more than starting clean.
What slows an ADU down most in the City of Los Angeles?
Clearances, not plan check. LADBS plan check runs alongside City Planning, Fire, LADWP and Sanitation, and the project moves at the pace of the slowest department. Hillside, HPOZ and Coastal flags each add their own review, which is why we pull them from ZIMAS before design starts.
Do you handle the permits in Los Angeles, or do I?
We do — design, engineering, submittal and every correction, dealing with the Los Angeles reviewers directly.
Should I use one of the City’s pre-approved plans?
If your lot is level, your soil is ordinary and a catalogue size fits what you actually need, it is a real saving on design fees and it shortens plan check. If you are on slope, have an unusual footprint, or the layout genuinely matters to you, a custom design is normally the better answer — and the free YOU-ADU set in particular is engineered for level grade. Our standard plans guide lays out the assumptions in full.
My property is in the Coastal Zone. Is that a problem?
It is a different approval track rather than a barrier, and it adds time. The practical consequence is that the sequence matters more: we establish what the Coastal position is during feasibility, before a design exists to be revised. Budget for the additional review when you plan the schedule.
Can we stay in the house while you build?
For a detached unit or a garage conversion, yes, and most clients do. On the alley-fed blocks it is easier still, because deliveries and site traffic come off the alley rather than past your front door. A junior ADU inside the house is the exception — that one takes a bedroom and part of the plumbing out of service.
Will you tell me if my lot is a bad candidate?
Yes, and the site walk is free so that we can. A hillside parcel where engineering swallows the budget, an LADWP upgrade that changes the maths, a Coastal position that adds months — we would rather say so in the first two hours than take a deposit. You get a written proposal within 48 hours, and it either carries a real number or explains why we think you should not proceed.
Next steps
For what the code allows on your lot, see Los Angeles ADU rules or run the ADU rules calculator. For our scope, process and warranty, see ADU construction, garage conversions and how we run a project. Our garage-to-ADU conversion is photographed at every stage. Green Design and Build is CSLB #1110975, licensed, bonded and insured.