Detached ADU
A new backyard residence shaped around the lot, access, utilities and intended use.
Los Angeles accessory dwelling units
ADU design and construction, resolved around your property.
RSA coordinates feasibility, design, approvals and construction for detached ADUs, attached units and garage conversions across Greater Los Angeles.
The useful first answer
Can an ADU work here?
That answer begins with the address—not a standard plan or a square-foot price. Lot geometry, existing buildings, access, utilities, easements and the reviewing authority can change the practical path.
An early property study should identify what is known, what requires confirmation and which professional inputs are needed before budget or schedule commitments are made.
The service at a glance
What RSA does, what your property needs, and how the work is sequenced
Scope RSA coordinates
- Property review: records, jurisdiction, access, existing structures and utility paths.
- Feasibility and scope: which ADU type fits, what needs a survey, soils or engineering input.
- Design and engineering coordination through a complete permit submission.
- Responses to agency corrections and coordination of utility applications.
- Construction, inspections and closeout under a written scope and change-order process.
Property prerequisites to confirm
- A lot zoned for residential or mixed use with an existing or proposed primary dwelling.
- The agency that actually reviews the parcel (city, county or coastal authority).
- Existing permits and any unpermitted work on the lot.
- Access for construction, and where water, sewer, electric and gas can connect.
- Easements, protected trees, slope, fire or flood mapping that may change scope.
State baseline: Gov. Code § 66314 and the HCD ADU handbook; local standards and parcel conditions still apply. Reviewed September 26, 2026.
How the work is sequenced
- 01Property review and a written list of unknowns.
- 02Feasibility, scope and a budget built from that scope.
- 03Design, engineering and a complete application.
- 04Agency review and applicant corrections.
- 05Utility work, construction and inspections.
- 06Final inspection and closeout documents.
No fixed duration is promised: agency review clocks run only after a complete application, and corrections, utility work and inspections depend on the project. See the permit timeline guide.
Choose the right path
Three common ADU starting points
Garage conversion
A study of the existing structure, foundation, ceiling height, openings and utility path.
Explore garage conversionsAttached ADU or JADU
A compact addition or conversion coordinated with the primary home and its systems.
Before design begins
Confirm the responsible planning and building authority.
Review available property and permit records.
Document existing structures, access and utility conditions.
Define intended use, spatial priorities and decision criteria.
Identify survey, engineering or specialist input that may be required.
Build the scope before relying on a budget or schedule.
Service fit
Is a full accessory dwelling unit the right project here?
Usually the right starting point when
- The lot already has — or will have — a single-family or multifamily home, and there is room for a separate entrance, a path of travel and usable outdoor space.
- The unit needs to stand on its own long term: full kitchen, full bathroom, its own heating and cooling, and its own or sub-metered services where the utility allows it.
- Long-term rental income or housing a family member matters more than resale of the unit itself, which state law does not allow separately from the house.
- You can share the address early, so the reviewing authority, overlays and utility conditions are checked before anyone draws a floor plan.
Check these before committing
- If sharing the kitchen with the main house is acceptable, a junior unit inside the existing walls is often the shorter and cheaper route.
- Very high fire hazard severity zones, historic districts, hillside and coastal parcels add review layers that should be identified before a footprint is fixed.
- Sewer capacity, an undersized electrical service, recorded easements or an existing unpermitted structure can each change the sequence of work.
- If you need a fixed price before any investigation, the number cannot be defensible — it follows the survey, the utility check and an agreed scope.
What the service includes
Five phases, each with something you can hold
Scope is written down phase by phase so you can see what is being done, what it produces and where a decision is owed from you.
- 01
Property study
The work: Confirm which agency reviews the property, read the available permit and property records, identify which statutory pathway fits, and list what is still unknown.
What you receive: A written feasibility summary separating confirmed conditions from items that need investigation.
- 02
Design
The work: Develop the unit plan, a site plan with dimensioned setbacks, the envelope and the systems strategy, and coordinate the consultants the property requires — survey, soils, structural, energy compliance.
What you receive: A coordinated drawing set intended for submittal, with the consultant reports it depends on.
- 03
Submittal and plan check
The work: Assemble the application so it can be deemed complete, then track and answer plan-check corrections through to issuance.
What you receive: Correction responses on the record and an issued building permit.
- 04
Construction
The work: Site work, utilities, foundation, framing, rough-in of mechanical, electrical and plumbing, inspections, then finishes and fixtures.
What you receive: Signed inspection records at each stage rather than progress described in conversation.
- 05
Closeout
The work: Final inspection chain, occupancy approval, correction of punch items, and handover of documentation.
What you receive: Occupancy approval, as-built documents, appliance and system manuals, and the warranty package.
Process milestones
The gates that actually move the project
Each milestone closes on something verifiable. Nothing below is a promised date — dates depend on the agency, the consultants and the decisions still open.
- 01
Address reviewed
Closes when: The reviewing authority and the available statutory pathways are confirmed in writing.
- 02
Feasibility accepted
Closes when: You approve the scope and the list of unknowns that still need investigation.
- 03
Design frozen
Closes when: Layout, envelope and the required consultant reports are complete and consistent.
- 04
Application deemed complete
Closes when: Intake accepts the submittal, which is the event that starts the statutory 60-day decision period.
- 05
Permit issued
Closes when: Plan-check corrections are cleared and agency fees are paid.
- 06
Rough-in approved
Closes when: Framing and mechanical, electrical and plumbing inspections are signed off.
- 07
Occupancy approved
Closes when: The final inspection chain is complete and the unit is legally habitable.
Realistic dependencies
What sits outside anyone's control
These are the items that most often move a schedule. Naming them early is more useful than a confident calendar.
- Plan-check correction cycles. The statutory 60-day period runs from a completed application and is tolled for delays the applicant requests.
- Utility work — capacity review, meter and panel upgrades, and whether the unit gets its own service — runs on the provider's schedule, not the city's.
- Agency fees and impact fees vary by jurisdiction, and a local agency may charge fees to implement the state statute.
- Consultant reports. Survey, soils, structural and energy compliance all gate the drawings that follow them.
- Private restrictions. Recorded easements and HOA or CC&R provisions can constrain placement even where the city would approve it.
- Where a city publishes no local figure, the statewide baseline is what applies until that city's own current publication is confirmed for the address.
Statewide baseline
Rules that apply before any local ordinance is read
Read each of these against the current publication of the agency reviewing your property. They describe statewide law, not the conditions of a specific parcel.
A permitting agency must approve or deny a completed application to create an accessory dwelling unit within 60 days, and the application is deemed approved if it does not. The clock is tolled for any delay the applicant requests, so completeness at intake is what actually starts it.
Cal. Gov. Code § 66317A detached, newly built accessory dwelling unit is approved ministerially at four-foot side and rear setbacks. A city may still apply a floor-area limit of no more than 800 square feet of livable space and the statutory height limits.
Cal. Gov. Code § 66323(a)(2)A conversion inside the existing space of the house or of an accessory structure is approved ministerially, with expansion limited to 150 square feet beyond the existing structure and only to accommodate ingress and egress. The space needs exterior access, and side and rear setbacks must be sufficient for fire and safety.
Cal. Gov. Code § 66323(a)(1)An accessory dwelling unit may be rented separately from the primary residence, but it may not be sold or conveyed separately from it outside the narrow statutory exceptions.
Cal. Gov. Code § 66314(a)(1)An accessory dwelling unit is not required to have fire sprinklers if they are not required for the primary residence, and building one does not trigger a sprinkler retrofit of the existing house.
Cal. Gov. Code § 66314(d)(12)A junior accessory dwelling unit is limited to one per lot, must sit within the walls of the proposed or existing single-family residence — an attached garage counts as within it — and carries a recorded deed restriction against separate sale. Owner-occupancy applies only where the junior unit shares sanitation facilities with the house.
Cal. Gov. Code § 66333
Read from the official code text on 24 September 2026. Statutes change; confirm the current section before relying on it.
Decisions people actually face
Questions worth settling before design starts
Answers below are statewide and source-cited. What applies to your parcel has to be confirmed with the reviewing agency.
How long does the city have to decide on the application?
Sixty days from a completed application, and if the agency does not approve or deny it in that period the application is deemed approved under Cal. Gov. Code § 66317. The practical lever is completeness at intake — the period is tolled for any delay the applicant requests, so a submittal that is not accepted as complete has not started the clock at all.
Do I have to live on the property to build an ADU?
State law does not impose owner-occupancy on an accessory dwelling unit. It does for a junior accessory dwelling unit that shares sanitation facilities with the house, and that requirement drops away when the junior unit has its own sanitation facilities, under Cal. Gov. Code § 66333.
Can I sell the ADU separately later?
No, outside the narrow statutory exceptions. Cal. Gov. Code § 66314(a)(1) allows the unit to be rented separately from the primary residence but not sold or otherwise conveyed separately from it. Plan the project around rental income or family use rather than a future separate sale.
Detached new build, or convert the garage?
The condition of the existing shell usually decides. A conversion inside existing space is ministerial but expansion is capped at 150 square feet and only for ingress and egress under Cal. Gov. Code § 66323(a)(1), so the current footprint is close to the finished footprint. A detached new unit is ministerial at four-foot side and rear setbacks and can be sized to the plan, subject to a local livable-area cap of up to 800 square feet under § 66323(a)(2).
Will building an ADU force fire sprinklers into my existing house?
No. Cal. Gov. Code § 66314(d)(12) states that an accessory dwelling unit is not required to provide fire sprinklers where they are not required for the primary residence, and that constructing one does not trigger a sprinkler requirement in the existing dwelling.
What do you need from me before a real number is possible?
The address and parcel number, any permit history the city holds, access to walk the site, and a decision on intended use and size. From there the survey, the utility capacity answer and the agreed scope are what a defensible figure is built on. A square-foot average quoted before those is a guess wearing a number.
Primary sources
Verify rules with the agency responsible for the property.
State guidance is a starting point. Local review, site conditions and the submitted scope determine what applies to an individual project.
Keep researching
Move from the lot question to a documented decision
Garage conversion
What an existing garage has to satisfy before it can be lived in.
Build the budget
Separate known costs, allowances, exclusions and unknowns before comparing totals.
Prepare a funding decision
Compare cash, equity and construction-finance questions without treating examples as offers.
Compare proposals
Align scope, allowances, exclusions, responsibilities and unknowns.
Navigate permits
Find the authority, assemble documents, track corrections and clear referrals.
Evaluate preapproved plans
Compare plan approval with the site-specific work still required.
Decision answers
What to settle before an ADU design starts
Is my lot eligible for an ADU in Los Angeles?
State law allows at least one ADU and one JADU on most single-family lots, but the reviewing city — not the mailing address — decides the details. Confirm the jurisdiction first; a Beverly Hills ZIP code can sit inside the City of Los Angeles.
How much ADU activity is there locally?
In August 2026, the City of Los Angeles authorized 2,478 new housing units, of which 343 were in one-unit buildings (Census Building Permits Survey). ADUs are not reported separately in that survey, so treat it as context for small-building activity, not an ADU count.
Source: U.S. Census Bureau — Building Permits Survey, place files
How do I compare two ADU bids fairly?
Line up design, engineering, permits, utilities, site work, structure, finishes and contingency for each bid, and keep excluded or unknown items open instead of counting them as zero.
Source: CSLB — license lookup
RSA location
Based in Beverly Hills, serving Greater Los Angeles.
8484 Wilshire Blvd, Beverly Hills, CA 90211
(818) 724-8623Before a consultation
What to bring to a first property conversation
The more of this is available, the sooner the conversation moves from general guidance to your specific property.
Send property detailsThe enquiry form is the current intake route. Nothing is committed by sending it.
- The property address, and the parcel number if you have it.
- Any plans, surveys, permit records or reports already in hand.
- Photos of the areas involved, including the existing structures.
- How the finished space should be used, and by whom.
- Constraints you already know about: access, tenants, trees, easements, HOA review.
- Where you are in the process, and what decision you are trying to make next.
Property review