$80,000 – $350,000+
Detailed cost breakdown for adu and garage conversion projects in Southern California, Los Angeles, Ventura, and Orange County.
ADUs (Accessory Dwelling Units) are one of the smartest investments a Southern California homeowner can make, adding rental income, multigenerational living space, or significant home value. Costs range from $80,000 for a garage conversion to $350,000+ for a detached new-build ADU with full architectural services.
Pricing depends on scope, materials, and complexity. Below are the three typical project tiers we see across Southern California.
Here's how a typical adu and garage conversion budget breaks down by component. Percentages can vary based on your specific project scope and material choices.
| Component | Typical Cost Range | % of Total Budget |
|---|---|---|
| Framing & structure | $25,000 – $80,000+ | 20–30% |
| Foundation (detached ADU) | $15,000 – $40,000 | 10–15% |
| Plumbing rough-in & fixtures | $12,000 – $30,000 | 8–12% |
| Electrical & HVAC | $12,000 – $30,000 | 8–12% |
| Kitchen (cabinets, counters, appliances) | $10,000 – $30,000 | 8–12% |
| Bathroom (tile, fixtures, vanity) | $8,000 – $20,000 | 5–10% |
| Flooring, drywall & finishes | $8,000 – $25,000 | 6–10% |
| Roofing & exterior | $8,000 – $25,000 | 6–10% |
| Design, permits & project management | $10,000 – $30,000 | 8–12% |
Ranges reflect 2026 Southern California market pricing for standard to premium materials and finishes. Final costs depend on your specific scope, material selections, and site conditions.
Every project is unique. Here's what most affects the final price of your adu and garage conversion.
ADUs in California can be up to 1,200 sq ft. Cost per square foot is fairly consistent, bigger ADU equals more cost.
Flat, accessible lots cost less than hillside, narrow, or difficult-access sites. Trenching for utilities adds cost.
Connecting to existing utilities is cheaper than running new sewer, water, gas, or electrical lines.
Standard finishes vs. premium materials can swing total cost by $30,000–$75,000+.
California state law has streamlined ADU permitting, but cities still vary in fees and review timelines.
Detached new builds cost more than attached ADUs or garage conversions due to foundation, roof, and full structural work.
Garage conversions run $80,000–$150,000. Attached ADUs run $150,000–$250,000. Detached new-build ADUs run $250,000–$350,000+ for standard finishes, more for premium. All-in cost depends on size, site, and finishes.
Garage conversions: 3–5 months including permitting. Attached ADUs: 6–9 months. Detached new builds: 8–12 months including design, permitting, and construction. California's streamlined ADU permitting helps move things faster than traditional builds.
Yes. Under California state law, homeowners can rent ADUs, this is one of the primary benefits. ADU rental income in Los Angeles typically ranges from $2,000–$4,000+ per month depending on size, location, and finishes.
Yes, ADUs require permits. The good news: California state law (SB 9, SB 1211, AB 2221) has dramatically streamlined ADU permitting compared to traditional construction. Most cities now process ADU permits in 60 days or less.
Yes. ADUs add meaningful property value in Southern California, typically $100,000–$300,000+ depending on the ADU's size and quality. The combination of added square footage and rental income potential makes ADUs one of the highest-ROI home investments available.
Free, no-pressure consultation within 72 hours. Tell us about your project, we'll tell you what's possible, what it'll cost, and how long it'll take. Honestly.
We've received your form and will be in touch within 24 working hours to talk about your project.
In a hurry? Call us anytime at (800) 209-0031