August 11, 2025
A Modern Guide to Accessory Dwelling Units.
ADU Cost in California
How Much Does It Actually Cost to Build an ADU in California?
The real numbers no one wants to tell you (but we will)
The Most Loaded Question in Backyard Construction
How much does it cost to build an ADU in California?
That’s like asking how long it takes to get from LA to New York.
Are you flying first class? Pedaling a bike? Riding a Vespa with your dog in a sidecar?
It depends.
We speak with dozens of homeowners each day and have worked on dozens of projects across the state. So here’s our honest, up-to-date breakdown of ADU costs in California for 2025.
We’ll cover:
- Cost ranges (traditional vs. prefab)
- What drives those costs up or down
- The hidden costs nobody advertises
Let’s break it down.
💸 The Real ADU Cost Range in California (2025)
For a legal, livable 2-bedroom ADU in California, here’s what you’re realistically looking at:
- Bare-bones prefab (e.g., Boxable)
- Advertised: $70K
- Reality: $150K+ with site work, delivery, and utilities
- Entry-level traditional build: $150K–$200K (not including permits, finishes, or change orders)
- Standard traditional build: $250K–$420K (depending on management, lot conditions, and finishes)
- High-end prefab (like LiveLarge): $320K–$500K all-in (permits, site work, delivery, installation)
- Architect-designed custom: $400K+ and up (limited only by budget and imagination)
Why such a range? Just like cars, the difference between a Toyota and a Lexus comes down to materials, design, and build quality. It’s no different with ADUs.
Framing, insulation, cabinetry, fixtures, soundproofing, and finishes all affect the price. The correlation between cost and quality is strong — though not always linear.
🛠️ Traditional vs. Prefab: Apples and Oranges
Prefab isn’t “cheaper construction.” It’s a different method of building.
- Traditional Build:
- Stick framing
- Built entirely on-site
- Lots of subcontractors
- Prone to delays and change orders
- Prefab (LiveLarge):
- Steel-framed modules
- Triple-paned windows
- Luxury interiors
- Factory-built for speed, craned into place
- 6–8 month timeline, with only ~30 days of onsite work
You don’t manage subcontractors. You’re not living in a construction zone. And you’re not at the mercy of weather delays.
You just move forward.
🏠 What Our Customers Actually Pay
Here’s a snapshot of our all-in pricing at LiveLarge. Yes, we mean all in:
| Unit | Size | Unit Price | Site Work(Est.) | Total Range |
|---|---|---|---|---|
| Studio | 350 sq ft | $205K | $40K–$50K | ~$245K–$255K |
| 1 Bedroom | 520 sq ft | $250K | $40K–$50K | ~$290K–$300K |
| 2 Bedroom | 750 sq ft | $340K | $50K+ | ~$390K+ |
| L-795(2 BR) | 795+ sq ft | $345K+ | $50K–$60K | ~$395K–$415K |
That includes:
- Permitting
- Foundation
- Delivery + craning
- Trenching and utility hookups
- Final install and inspection
So when someone tells you they saw a $180K ADU online, ask:
Does that include site work, utilities, permits, delivery, and install?
If not, you’re not comparing the same thing.
Not All Square Footage Is Created Equal: HUD vs. HCD
This is the most overlooked (and most important) part of ADU cost:
- HUD-certified units (like some mobile homes or cheap prefabs):
- Treated like personal property (like a car)
- Don’t count toward your home’s square footage
- Don’t boost your home’s appraisal
- Depreciate over time
- HCD-certified units (like LiveLarge):
- Count as real, permanent square footage
- Add to your home’s value
- Appreciate with the market
- Are treated as real property by banks, cities, and buyers
This one distinction can mean hundreds of thousands of dollars when you refinance or sell.
🧠 It’s Not Just About the Money
Building an ADU impacts your time, stress level, and quality of life.
Traditional ADU Builds:
- 12–18 months of disruption
- Managing subs
- Rain delays
- Permit headaches
- Surprise costs
LiveLarge Prefab:
- One integrated team
- Clear timeline
- Predictable pricing
- Built in a factory while your lot is prepped
- Installed in a few days
We don’t hand you a brochure and say “good luck.”
We guide you from your first call to your final inspection.
📃 What Most Quotes Leave Out
Here are the common ADU costs left out of most websites or contractor estimates:
- Site prep and trenching
- Utility connections
- Permit fees ($5K–$20K+)
- Tree removal or grading
- Foundation install
- Landscaping repairs
- Delivery and craning
- Inspections and project management
These aren’t minor. Combined, they often add $40K–60K.
We include these upfront. No nasty surprises.
💬 “But I Saw One Online for $100K…”
Sure you did. But that probably didn’t include:
- A foundation
- Utility hookups
- Installation
- Permits
- Project oversight
That’s like listing a car for $20K but selling the wheels and steering wheel separately.
You get what you pay for.
✅ Next Steps
📍 Not sure if your lot qualifies?
→ [Check My Backyard] — free + instant
🏡 Want to see a real unit in person?
→ [Visit our San Jose or Los Angeles showroom]
📞 Ready to start planning?
→ [Book a strategy call with our team]
Discover More
August 11, 2025
The ADU choice made simple.
August 11, 2025
Here’s how to know in minutes.