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What Does an ADU Really Cost in San Diego?
Let’s be super honest with you. In San Diego, the cost to build an Accessory Dwelling Unit (ADU) can range from $150,000 to $450,000 or more, depending on size, design, and other factors. Smaller attached ADUs (JADUs) may start around $150,000, while larger detached ADUs can exceed $300,000.
But here’s the thing – most contractors won’t tell you the real story. They’ll give you a low number to get you excited, then hit you with surprise costs later. We don’t play those games.
Real ADU Costs in San Diego (2025)
| ADU Type | Size Range | San Diego Cost | What You Get |
|---|---|---|---|
| Junior ADU (JADU) | 400-500 sq ft | $120,000 – $200,000 | Small space, basic kitchen, shares utilities |
| Attached ADU | 500-800 sq ft | $200,000 – $350,000 | Connected to main house, full kitchen & bath |
| Detached ADU | 600-1,200 sq ft | $250,000 – $500,000+ | Separate building, complete living space |
| Garage Conversion | 400-600 sq ft | $150,000 – $275,000 | Turn existing garage into living space |
San Diego has strict rules, expensive permits, and high labor costs. Plus, our year-round perfect weather means contractors are always busy, which drives prices up. But the good news? Your ADU will also be worth more when you’re done!
What Makes Your ADU Cost Go Up or Down?
1. Size Matters (But Not How You Think)
Bigger isn’t always more expensive per square foot. A 400 sq ft ADU might cost $400 per sq ft, while a 800 sq ft ADU might only cost $350 per sq ft. That’s because some costs (like permits and hookups) are the same no matter what size you build.
2. Where You Put It
Building in your backyard? Easy. Building where there are slopes, trees, or tricky access? That’s gonna cost more. We’ll tell you straight up if your lot has challenges.
3. What Goes Inside
Want granite counters and fancy fixtures? Cool, but it costs more. Want basic but nice finishes? We can do that too. Here’s what different choices cost:
| Feature | Basic | Nice | Fancy |
|---|---|---|---|
| Kitchen | $8,000 – $15,000 | $15,000 – $25,000 | $25,000 – $40,000+ |
| Bathroom | $6,000 – $12,000 | $12,000 – $20,000 | $20,000 – $35,000+ |
| Flooring | $3,000 – $6,000 | $6,000 – $12,000 | $12,000 – $20,000+ |
4. The Boring Stuff (That Costs Real Money)
Nobody gets excited about permits and utility hookups, but they’re a big part of your cost:
- Permits: $3,000 – $8,000 (depending on your city)
- Utility Hookups: $5,000 – $15,000 (electricity, water, sewer)
- Impact Fees: $8,000 – $20,000 (city fees that vary by location)
How to Pay for Your ADU (Real Talk)
Let’s be honest – ADUs cost real money. But here’s the good news: there are ways to make it work without breaking the bank.
Popular Ways San Diego Folks Pay for ADUs:
- Home Equity Loan: Borrow against your house value (rates around 7-9%)
- Cash-Out Refinance: Replace your mortgage with a bigger one
- Construction Loan: Special loan just for building (we can help you find lenders)
- Save Up: Takes longer but no interest payments
Rent a 1-bedroom ADU in San Diego for $2,500/month = $30,000/year. If your ADU costs $300,000, you’ll make your money back in about 10 years. Plus, your home value goes up by about 70% of what you spend!
Why ADU Costs Are All Over the Map
Ever wonder why one contractor says $200,000 and another says $400,000 for the same ADU? Here’s why:
The Good Contractors Include Everything
When we give you a price, it includes permits, inspections, utility hookups, and dealing with the city. No surprises.
The Cheap Guys Leave Stuff Out
They give you a low price to win the job, then hit you with “extras” later. We’ve seen families get charged an extra $50,000 for things that should have been included.
Experience Costs More (But Saves You Money)
We’ve built hundreds of ADUs. We know what works, what doesn’t, and how to avoid expensive mistakes. Yes, we cost more upfront, but we save you money and headaches in the long run.
Cool ADU Ideas That Won’t Break the Bank
The Smart Family Setup
600 sq ft attached ADU with one bedroom, full kitchen, and bathroom. Perfect for grandparents or college kids. Cost: $220,000 – $280,000
The Rental Money Maker
800 sq ft detached ADU with two bedrooms, full kitchen, and nice finishes. Rent for $2,800/month. Cost: $280,000 – $350,000
The Home Office Plus
500 sq ft with office space, small kitchen, and bathroom. Work from home in style! Cost: $180,000 – $240,000
Ready to Build Your Dream ADU?
Look, building an ADU is exciting, but it can also feel overwhelming. We get it. That's why we make it simple.
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