Building an ADU in Los Angeles: Costs, Permits, and Planning
Updated: 4 hours ago
An accessory dwelling unit can give your family more room while keeping everyone close. It can also create a separate home for guests or a potential long-term rental. Before choosing a floor plan, though, it helps to answer three practical questions: What can your property accommodate, what will the complete project cost, and what approvals will you need?
If you’re considering building an ADU in Los Angeles, start with the property and your goals. Those two factors shape the design, budget, and construction plan.
What is an ADU?
An accessory dwelling unit, or ADU, is an independent residence on the same property as a primary home. It includes space for living and sleeping, cooking facilities, and a bathroom.
Common options include a detached backyard unit, an attached addition, or a conversion of existing space. A junior accessory dwelling unit, or JADU, is a separate category with its own requirements. California defines a JADU as no more than 500 square feet within a single-family residence; it may have its own bathroom or share one with the main home. See the California HCD ADU Handbook for the current definitions and rules.
Which type of ADU fits your property?
Start by considering who will use the space and how they will move between the street, the main house, and the new unit.
Detached ADU: A separate backyard home is worth exploring when privacy is a priority. Consider the entrance, outdoor space, window placement, and how much yard you want to retain.
Attached ADU: An addition connected to the main home may suit your layout. Pay particular attention to the relationship between the two homes, including entrances and sound separation.
Garage conversion: Converting a garage is another option to investigate. Before committing to a layout, have the existing structure evaluated and identify the work needed to create residential living space.
JADU: A smaller unit within the home may fit a different set of goals. Review the specific JADU requirements before assuming it follows the same rules as a full ADU.
Sketch how each option would affect everyday life. Where will deliveries arrive? Where will residents store belongings? Will the main house still have a comfortable outdoor area?
How much does an ADU cost in Los Angeles?
A useful ADU budget starts with a defined scope. Square footage alone does not tell you what is included in an estimate.
When comparing proposals, ask for these items to be identified:
Design, engineering, and any required property investigations.
Permit applications, plan review, and applicable fees.
Demolition, excavation, and site preparation.
Foundation and structural work.
Water, sewer, electrical, and other utility work.
Kitchen, bathroom, heating, cooling, and finishes.
Exterior restoration, paths, drainage, and landscaping.
Allowances, exclusions, and a contingency for unforeseen work.
Ask whether the number you receive represents construction alone or the complete anticipated project. Also clarify which selections are fixed and which remain allowances.
For example, two proposals may both include a kitchen but allow different amounts for cabinetry, appliances, and countertops. Comparing those details early gives you a clearer picture of the budget.
Ohayon Construction starts with a discussion of your property, goals, scope, and budget. Learn more about our ADU construction services in Los Angeles.
Is a garage conversion the right choice?
An existing garage can be a useful starting point, but its suitability needs a closer look.
Before moving forward, ask your project team:
What existing foundation, framing, and roofing can remain?
What changes are needed for insulation, moisture protection, and ventilation?
How will plumbing and electrical services reach the unit?
Where can windows and an entrance be placed?
Can the layout accommodate a practical kitchen, bathroom, and storage?
What happens to the items and activities currently housed in the garage?
Compare the proposed conversion with a detached ADU using the same level of detail. This helps you weigh cost, layout, privacy, and the effect on your property.
What should you know about Los Angeles ADU permits?
Confirm the permitting jurisdiction for your address before relying on a checklist. The City of Los Angeles, unincorporated Los Angeles County, and neighboring cities may use different submission processes.
For properties within the City of Los Angeles, the Department of Building and Safety’s ADU resources provide local guidance and information about its Approved Standard Plans Program. Approved standard plans can reduce plan-review work, but the city still reviews how a selected plan fits the property, including zoning and foundation requirements.
At your initial planning meeting, ask who will prepare the application, respond to review comments, coordinate required approvals, and track the permit process. Get those responsibilities written into the project scope.
How long does ADU construction take?
Ask for a schedule that separates design, permitting, construction, and project closeout. A construction estimate should clearly state when its clock starts.
As one project example, Ohayon Construction’s approximately 500-square-foot detached, one-bedroom ADU in Beverly Hills was completed in 2026 with approximately six months of construction. That example is described on our ADU services page; it is not a guaranteed timeline or an estimate of permitting time for another property.
For your project, discuss what must happen before work begins and which decisions you need to make along the way. Request updates when approvals, material selections, or changes affect the schedule.
Plan the interior around daily life
A compact home deserves careful attention to everyday details. Before finalizing the design, work through the furniture layout and storage needs.
Consider where a dining table will fit, how bedroom doors will open, where laundry will go, and whether there is room for cleaning supplies and seasonal belongings. Think about privacy between the ADU and the main house, particularly where windows and outdoor seating face each other.
If the unit is intended for a family member, discuss their current needs and how those may change. Bring those priorities into the design conversation early.
Questions to ask an ADU contractor
Bring these questions to your consultation:
What information do you need to evaluate my property?
Which ADU options should we compare?
Who is responsible for design, engineering, and permits?
What is included in the estimate, and what is excluded?
How are allowances and changes documented?
What milestones will appear in the schedule?
How will progress and open decisions be communicated?
Clear answers help you understand the proposed work before making a commitment.
Start planning your Los Angeles ADU
Whether you’re exploring a garage conversion or a detached backyard home, the first step is a conversation about your property and how you want to use the space.
Ohayon Construction provides ADU construction and garage-conversion services in Los Angeles and surrounding communities. Contact us for a free consultation to discuss your goals, budget, and next steps.
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