How Much Does an ADU Cost in Los Angeles? (2026) | Oasis Pool Company

The honest range for ADU construction in Los Angeles in 2026 is $90,000 to $400,000. That spread is wide because a garage conversion and a detached two-bedroom new-build are fundamentally different projects. Below is what each type actually costs, what drives the number up, and where the hidden fees live.

ADU Cost by Type

Garage Conversion

$90,000 – $200,000 · $200–$350 per sq ft

The shell exists. You are paying for structural reinforcement, insulation, plumbing, electrical, HVAC, fire sprinklers, and finishes — not foundation and framing. A standard two-car garage conversion with one bedroom, one bathroom, and a kitchenette typically lands around $120,000 to $160,000 in LA County. See our garage conversion service for scope and timeline details.

The biggest wildcard is foundation. Many LA garages have a 3.5-inch slab with no footings — fine for parking a car, not for a dwelling. Deepening the foundation or pouring a new one adds $8,000 to $20,000.

Attached ADU

$150,000 – $300,000 · $250–$400 per sq ft

An addition to your existing home. Shares at least one wall with the main structure, which saves on some exterior work but requires fire-rated separation between the units. Costs are higher than garage conversions because you are building new walls, roof, and foundation — but lower than fully detached because you share one wall and often tap into existing utility runs.

Detached ADU

$200,000 – $400,000 · $280–$450 per sq ft

Ground-up construction — new foundation, framing, roofing, full MEP, and exterior. This is a small house built in your backyard. The premium over garage conversions comes from foundation work, framing, roofing, and longer construction timelines. At the high end, premium finishes, hillside access, and soils engineering push detached ADUs past $400,000. Our detached ADU service covers design through certificate of occupancy.

Junior ADU (JADU)

$40,000 – $100,000 · $150–$250 per sq ft

A unit carved from existing space inside the main home — typically a bedroom with an added bathroom and kitchenette. The cheapest option because you are converting existing square footage, not building new. California caps JADUs at 500 sq ft.

What Is Included in These Numbers

These cost ranges cover construction only — the work your contractor does on site. Specifically:

• Design and engineering plans
• Permit coordination and submittals
• Foundation, framing, roofing (for new-build)
• Plumbing, electrical, HVAC, fire sprinklers
• Insulation and Title 24 energy compliance
• Drywall, paint, trim, flooring
• Kitchen cabinets, countertops, appliances
• Bathroom fixtures and tile
• Exterior stucco or siding
• Basic landscaping restoration

What Is NOT Included (The Hidden Costs)

These are the line items that catch homeowners off guard. Budget an additional $15,000 to $40,000 on top of construction costs.

Permit fees: $5,000 to $25,000 depending on unit size and city. Units under 750 sq ft are exempt from most impact fees under state law. Larger units trigger school fees ($3 to $5 per sq ft), park fees, and sewer connection charges.

Soils / geotechnical report: $3,000 to $8,000 when required by the city. Common on hillside lots, lots with fill, or properties near fault zones. Not every project needs one.

Utility connections: $2,000 to $10,000 for separate water, sewer, and electrical connections. Some cities require a separate utility meter for the ADU. LADWP charges $2,000 to $5,000 for a new electrical meter panel.

Design and architecture fees: $8,000 to $25,000 depending on complexity. Some builders include basic design in their construction price. Custom architectural design costs more. We include design in our construction contract.

Surveying: $1,000 to $3,000 for a property survey to verify setbacks and lot lines.

Landscaping beyond basic restoration: $5,000 to $20,000 if you want privacy fencing, new plantings, pathway lighting, or hardscape around the ADU.

What Drives the Cost Up

In order of impact on your budget:

1. Site access. A flat backyard you can drive a concrete truck into costs less than a narrow side yard that requires a pump truck and hand-carried materials. Poor access can add $10,000 to $30,000.

2. Soils and foundation. Rocky soil, expansive clay, or a high water table mean more foundation engineering. Hillside lots near the Santa Monica Mountains often need caissons or retaining walls.

3. Unit size. More square footage means more of everything — foundation, framing, materials, labor, inspections. The cost per square foot does not decrease proportionally as you get larger.

4. Finish level. Builder-grade cabinets and LVP flooring vs custom cabinetry and hardwood. The spread between standard and premium finishes can be $30,000 to $60,000 on a 1,000 sq ft unit.

5. Fire sprinklers. Required in most LA jurisdictions. Cost: $3,000 to $8,000. Not optional — it is a code requirement.

6. Utility distance. If the sewer lateral or water main is far from the ADU location, trenching and connection costs increase. Units built close to the main house tap into existing runs more cheaply.

7. City jurisdiction. Permit fees, plan check timelines, and inspection requirements vary by city. Beverly Hills and Malibu tend to be more expensive and slower than LADBS or Thousand Oaks.

Cost by LA Neighborhood (Rough Ranges)

These are construction cost ranges based on typical lot conditions and access in each area. Not including permit fees and soft costs.

Ranges are wider in hillside areas and narrower on flat Valley lots. Get a real number from a site walk, not a website.

Financing Options

Most homeowners finance ADU construction through one of four paths:

Home equity line of credit (HELOC): Borrow against existing equity. Rates typically 7 to 10% in 2026. Works well when you have significant equity and want flexible draws during construction.

Cash-out refinance: Replace your existing mortgage with a larger one, take the difference as cash. Makes sense if your current rate is already high and you can consolidate at a similar rate.

ADU-specific construction loans: Lenders like HFS Financial and Lyon Financial offer pool and ADU construction loans from $25,000 to $500,000 with terms up to 20 years. We can connect you with lending partners who specialize in this.

CalHFA ADU grant: The California Housing Finance Agency has offered ADU grants up to $40,000 for qualifying homeowners. Availability and terms change annually — check calhfa.ca.gov for current program status.

Bottom Line

Budget $90,000 to $200,000 for a garage conversion and $200,000 to $400,000 for a detached new-build. Add $15,000 to $40,000 for permits, fees, and soft costs. The rental income — $2,000 to $4,000 per month in most LA neighborhoods — typically covers the financing cost with cash flow left over. The property value increase of $200,000 to $500,000 is the real return.

The fastest way to get a real number for your property is a 30-minute phone call. We will tell you what is feasible on your lot, what it will cost, and whether the math works before you spend a dollar on design.

Call (747) 293-9482 or request a quote. Full ADU construction scope on our site.

Published June 2026. Costs reflect Los Angeles, Ventura, and Orange County markets. Your project may vary based on site conditions, scope, and city requirements.*