Quick answer: An ADU costs $50,000–$280,000 in Los Angeles, ranging from a JADU interior conversion to a full detached new-construction unit. APLA Construction (CA Lic #1136359) provides free estimates across Greater Los Angeles.
How much does an ADU cost in Los Angeles? It is the first question every homeowner asks, and the answer depends significantly on the type of ADU, the size, the jurisdiction, and the condition of your property. In 2026, ADU construction costs in Greater LA range from $50,000 for a basic JADU to $300,000+ for a large detached new-construction ADU. This guide breaks down every cost component so you can budget accurately before starting. APLA Construction (CA Lic #1136359) has built ADUs across all of Greater Los Angeles and these numbers reflect current market reality.
A starting-point range based on real Los Angeles pricing — not a substitute for a free on-site estimate.
Estimates reflect typical Greater Los Angeles pricing as of 2026 and can vary based on site conditions, permitting jurisdiction, and design decisions. CA Lic #1136359.
| ADU Type | Typical Cost Range |
| JADU (Junior ADU) | $50,000–$90,000 |
| Garage conversion ADU | $80,000–$140,000 |
| Attached ADU | $120,000–$220,000 |
| Detached ADU (new construction) | $140,000–$280,000 |
The ranges above are wide because five factors move the number more than anything else:
A Junior ADU is carved out of existing interior space in the main home — typically a bedroom or den — and requires its own entrance and efficiency kitchen. No new structure is built. JADUs are the lowest-cost ADU type because they use existing square footage. Size is capped at 500 sq ft by state law.
The most popular ADU type in Los Angeles. An attached or detached garage is converted into a fully livable unit with kitchen, bathroom, bedroom, and living area. The existing structure eliminates foundation, framing, and roofing costs, making this the best value ADU for most LA homeowners.
An attached ADU shares one or more walls with the main home and may be built in a side yard, over a garage, or as a rear addition. It requires new construction for the walls and roof that don’t share with the main structure.
A fully detached new-construction ADU in the backyard is the most expensive type but also the most desirable for tenants and adds the most property value. Size can be up to 1,200 sq ft under California state law.
Ranges are useful for planning, but a full line-item budget shows where the money actually goes. Here’s an illustrative full budget for a typical 500 sq ft two-car garage conversion in the San Fernando Valley — studio layout, mid-range finishes, standard site conditions with utilities already close by:
| Line Item | Cost |
| Design and architectural drawings | $6,500 |
| Structural engineering | $2,500 |
| Permits and LADBS fees | $5,500 |
| Demo and site prep | $4,500 |
| Structural framing (door opening, insulation prep) | $8,000 |
| Electrical (sub-panel, full rough-in, fixtures) | $8,500 |
| Plumbing (kitchen + bath rough-in and fixtures) | $13,000 |
| HVAC (mini-split system) | $6,000 |
| Insulation and drywall | $9,000 |
| Kitchen (stock cabinets, laminate counters, appliances) | $16,000 |
| Bathroom (standard tile, fixtures, vanity) | $14,000 |
| Flooring (LVP throughout) | $6,500 |
| Windows and exterior doors | $8,000 |
| Paint, trim, and finish carpentry | $5,000 |
| Project management and contingency | $8,000 |
| Total | $121,000 |
That lands inside the $80,000–$140,000 garage conversion range above — toward the upper-middle because this example includes a full kitchen (not a kitchenette) and mid-range rather than budget finishes. A smaller unit, a kitchenette instead of a full kitchen, or stock everything at the lower end of each line item can bring a comparable project closer to $95,000–$100,000. APLA provides a real line-by-line estimate like this one for your specific property during the free consultation — not just a range.
The garage conversion above is the entry point. A detached ADU is a ground-up building, and the budget looks completely different — foundation, roof, exterior envelope, new utility laterals, and a solar system all appear that a conversion never pays for. Here is an illustrative full budget for a 750 sq ft detached one-bedroom ADU in the San Fernando Valley, mid-range finishes, level lot, standard soil, utilities within reach:
| Line Item | Cost |
| Design and architectural drawings | $11,000 |
| Structural engineering and Title 24 energy compliance | $4,000 |
| Permits, LADBS fees, and school fees | $8,500 |
| Site prep, grading, and utility trenching | $10,000 |
| Foundation (slab on grade) | $16,000 |
| Framing, sheathing, and roof structure | $30,000 |
| Roofing | $8,000 |
| Exterior stucco and paint | $13,000 |
| Windows and exterior doors | $9,500 |
| Electrical (new sub-panel, full rough-in, fixtures) | $12,500 |
| Plumbing (sewer and water laterals, rough-in, fixtures) | $17,000 |
| HVAC (ducted heat pump) | $8,500 |
| Solar PV system (required on new detached ADUs — see below) | $8,500 |
| Insulation and drywall | $11,500 |
| Kitchen (cabinets, quartz counters, appliances) | $18,000 |
| Bathroom (tile, fixtures, vanity) | $12,500 |
| Flooring (LVP throughout) | $8,000 |
| Paint, trim, and finish carpentry | $7,000 |
| Project management and contingency | $18,000 |
| Total | $231,500 |
That works out to roughly $309 per square foot — squarely inside the $140,000–$300,000 detached range above, near the top of the mid-range band. Compare it line-for-line against the garage conversion: the foundation, framing, roofing, exterior, and solar lines together are about $75,000 of work a conversion simply never buys. That single structural difference is most of the gap between a $121,000 project and a $231,500 one — not fancier finishes.
Why this example is 750 sq ft and not 800. That is a deliberate cost decision rather than a round number — see the fee threshold below.
A full ADU project cost from APLA includes:
Costs NOT typically included: landscaping restoration, appliance upgrades above standard package, and furnishings. Solar is the exception worth flagging: it is optional on a garage conversion or attached ADU, but legally required on a newly built detached ADU, so it is carried as a real line item in the detached budget above rather than treated as an upgrade.
Permit fees are included in the estimates above but here’s a breakdown of what LA homeowners pay in permits alone:
Most ADU cost guides stop at national averages. These four are specific to building in Los Angeles, and each one is worth real money on a decision you make before the drawings are finished.
State law prohibits any agency, special district, or water corporation from charging impact fees on an ADU of 750 sq ft or less of interior livable space (or a JADU of 500 sq ft or less). Above 750 sq ft, impact fees become chargeable and are prorated against the square footage of the primary house (California HCD ADU Handbook). In practice that is a hard cost cliff: a 780 sq ft ADU can carry several thousand dollars in fees that a 750 sq ft ADU on the same lot does not pay at all — for 30 sq ft of floor space nobody will ever notice. It is the most overlooked number in ADU planning, and it is why the sample budget above is sized the way it is.
The cliff softens on January 1, 2027. Under SB 1117 (Stats. 2026, ch. 809), on a lot with up to two ADUs, impact fees on an ADU over 750 sq ft may be charged only on the area above 750 sq ft (Gov. Code § 66311.5(c)(1)(B)). A 780 sq ft ADU permitted under the new rule would be charged on 30 sq ft, not 780. Lots with more than two ADUs keep the current proportional rule. Staying at 750 sq ft still avoids impact fees entirely, but going slightly over will no longer cost the full amount.
One important limit on that exemption. Impact fees are not the only fees an ADU can owe. State law defines an impact fee as expressly not including any connection fee or capacity charge (Gov. Code § 66311.5(c)(2)), so a 700 sq ft ADU can be exempt from impact fees and still owe a water connection fee and a sewer capacity charge. Those are a separate category with their own rules — see our guide to ADU utility connections and fees.
LADBS requires newly constructed detached ADUs to include solar panels, under California’s Building Energy Efficiency Standards (LADBS ADU requirements, California Energy Commission). A garage conversion, or an ADU carved out of existing space, is not new construction and does not trigger it. Budget roughly $8,000–$12,000 for the system on a detached build, and treat any detached quote that omits a solar line as incomplete rather than cheap.
LADBS does not require an off-street parking space for an ADU located within a half-mile of public transit. On a tight lot, that removes a paved space, a curb cut, and sometimes an entire redesign from the budget. Separately, since January 1, 2025, no California jurisdiction may require replacement parking when a garage or carport is demolished or converted to build an ADU — the old replacement-parking mandate is gone statewide. See our 2026 California ADU law guide for the full rules.
Los Angeles maintains an Approved Standard Plans program for ADUs — pre-reviewed designs where, in LADBS’s own words, using standard plans “shortens the time needed to review the plans through plan check, and corresponding permits are issued more quickly” (LADBS). You trade some design freedom for a faster, more predictable approval, and every month saved in permitting is a month of rent you start collecting sooner. Whether that trade is worth it depends on your lot; it is one of the first things we look at on a free consultation.
ADUs in Greater LA deliver strong returns because the rental market is among the most competitive in the United States. Here’s what the payback math actually looks like using the sample budget above:
| ADU Type | Typical Cost | Typical Rent | Gross Annual Income | Simple Payback |
| Garage conversion (500 sq ft, sample budget above) | $121,000 | $2,200/mo | $26,400 | ~4.6 years |
| Garage conversion, budget finishes | $95,000 | $1,900/mo | $22,800 | ~4.2 years |
| Detached ADU, mid-range | $210,000 | $2,800/mo | $33,600 | ~6.3 years |
“Simple payback” here means construction cost divided by gross rental income — before property taxes, insurance, maintenance, or vacancy, and before counting the $200,000–$400,000 in property value most LA ADUs add on top of the rental income itself. Actual after-expense payback runs longer, but this is the number that lets you compare ADU types on an apples-to-apples basis before those variables come into play.
In high-demand rental markets like Studio City, Culver City, Santa Monica, and Pasadena, rental rates are at the higher end of these ranges. See our guide to the best LA neighborhoods for ADUs.
A garage conversion ADU in Los Angeles costs $80,000–$140,000 in 2026 for a complete project including design, permits, and all construction. This makes it the most cost-effective ADU type. The existing garage structure eliminates foundation, framing, and roofing costs that add $50,000–$100,000 to a detached new-construction ADU.
A detached new-construction ADU in Los Angeles costs $140,000–$280,000 in 2026 depending on size (400–800 sq ft) and finish level. Larger ADUs approaching the 1,200 sq ft limit for detached ADUs in the City of Los Angeles can cost $250,000–$350,000. These figures include design, permits, and all construction.
Yes. Several financing options exist for LA homeowners building ADUs: cash-out refinance, home equity line of credit (HELOC), ADU-specific construction loans (offered by several California lenders). (CalHFA’s ADU grant is not currently available — its latest funding round was fully allocated in December 2023.) APLA can provide cost estimates and timelines needed for loan applications.
Yes, but only by the assessed value of the ADU addition — not the full market value. Under California’s Proposition 13, existing property is reassessed only when it changes ownership; only new construction (like your ADU) is assessed at market value as of completion. The ADU itself is assessed based on its construction cost and added to your property tax bill. A $150,000 garage conversion ADU typically adds $1,500–$2,000/year in property taxes. Some ADUs completed as long-term rentals may qualify for a temporary state property-tax exclusion under recent legislation — confirm current eligibility with the LA County Assessor’s office, since the rules and time limits have changed more than once.
Total ADU timeline from project start to Certificate of Occupancy is 9–12 months for a garage conversion and 12–18 months for a detached new construction ADU. The permit phase (4–8 weeks at LADBS) and construction phase (11–24 weeks depending on type) are the two largest time blocks. See our full ADU timeline guide.
The cheapest ADU option is a JADU (Junior ADU) carved from existing interior space — $50,000–$90,000. The cheapest option that creates a fully independent, rentable unit is a garage conversion ADU at $80,000–$140,000. Both are significantly less expensive than detached new construction and offer strong rental income potential.
APLA provides free on-site ADU evaluations throughout Greater Los Angeles. We will tell you what type of ADU your property can support, give you a realistic cost range, and explain the full permit and construction process.
Planning HVAC for your ADU? See our ADU HVAC & mini-split sizing guide.
Call: (818) 818-4419
Email: info@aplaconstruction.com
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Serving Sherman Oaks, Studio City, Encino, Culver City, Santa Monica, Pasadena, Glendale, Torrance, and all of Greater Los Angeles. the APLA ADU construction service, start to finish
Building an ADU outside Los Angeles County? APLA is licensed statewide (CA Lic #1136359) and also builds in Ventura County — Thousand Oaks, Simi Valley, Camarillo, Oxnard — and Orange County — Irvine, Anaheim, Huntington Beach, Newport Beach. The entitlement rules are state law and travel with you; what changes is which building department reviews the plans.