I get this question almost every week. Someone calls, tells me they want to build a backyard cottage or convert their garage, and the first thing they ask is: “How much is this going to cost me?”
Honest answer? It depends — but I can give you real numbers, not the vague ranges you find on most contractor websites.
I’ve built ADUs in both Sacramento and the Bay Area, and the difference in cost between the two markets is significant. Here’s what I’ve seen firsthand.
What’s Driving ADU Costs in 2026
Before we get into the numbers, you need to understand what actually moves the needle on ADU pricing:
- Size and layout — A 400 sq ft studio and a 1,200 sq ft two-bedroom are completely different projects
- Attached vs. detached — Detached ADUs cost more. You’re building a standalone structure with its own foundation, roof, and utility connections
- Garage conversion vs. new build — Conversions are generally cheaper because the shell is already there. New builds start from scratch
- Permit fees and utility hookups — This is where Sacramento and the Bay Area really diverge
- Site conditions — Slope, soil type, existing utilities — all of it matters
Sacramento ADU Costs
In Sacramento and the surrounding suburbs — Roseville, Folsom, Elk Grove, Carmichael — you’re generally looking at:
- Garage conversion: $80,000 – $130,000
- Attached ADU addition: $150,000 – $220,000
- Detached ADU (new build): $200,000 – $320,000
Sacramento has relatively straightforward permitting compared to the Bay Area, and labor costs are lower. Permit fees typically run $5,000 – $15,000 depending on the city and the scope of work. The City of Sacramento has also streamlined ADU approvals in recent years, which means faster timelines.
One thing I tell Sacramento clients: don’t cheap out on the design phase. I’ve seen homeowners save $10K by skipping proper drawings, then spend $30K fixing problems mid-construction. Get it right on paper first.
Bay Area ADU Costs
San Francisco, Oakland, Berkeley, Palo Alto — the Bay Area is a different animal. Everything costs more: labor, permits, materials, and time.
- Garage conversion: $120,000 – $200,000
- Attached ADU addition: $200,000 – $350,000
- Detached ADU (new build): $280,000 – $500,000+
San Francisco in particular has complex permitting. Depending on the neighborhood and the age of your home, you could be dealing with historic review, seismic requirements, or planning department approval on top of standard building permits. That adds time and money.
Labor costs in the Bay Area run 20–40% higher than Sacramento, and subcontractors are booked out further. A project that takes 6 months in Folsom might take 9–10 months in San Francisco just due to scheduling and inspection timelines.
That said — the ROI is also stronger. A well-built ADU in the Bay Area can generate $2,500–$4,000/month in rental income. In Sacramento, you’re looking at $1,200–$2,000/month. The numbers still pencil out well in both markets, but the Bay Area payback period can actually be faster given the rental rates.
What a Design-Build Approach Does for Your Budget
Here’s what I’ve learned after 13 years in this business: the biggest cost overruns happen when design and construction are disconnected. You hire an architect, they draw something beautiful, and then a contractor bids it and you find out it’s $150K over your budget. Now you’re back to square one.
When design and construction are handled by the same team — what we do at Hand + Hammer — you get accurate cost estimates during the design phase, not after. We design to your budget. We know what things cost because we’re the ones building it.
That’s not a marketing pitch. It’s just how the math works.
So What Should You Budget?
If you’re in Sacramento or the surrounding suburbs, plan for $200K–$300K for a quality detached ADU. If you’re in the Bay Area, start your mental budget at $300K and up.
Those numbers might feel big. But compare them to what a rental property costs to buy in either market right now. An ADU is often the most affordable way to add income-generating real estate to your portfolio — and you already own the land.
If you want a real number for your specific property, call us. We’ll come out, look at what you’ve got, and give you a straight answer. No fluff.
📞 (415) 572-9897
🌐 handhammerdev.com
Hand + Hammer Design Build serves Sacramento, the San Francisco Bay Area, and Silicon Valley. Licensed California General Contractor.