In the Sacramento area, a junior ADU typically costs $50,000 to $100,000, a garage conversion $80,000 to $150,000, an attached ADU $100,000 to $300,000, and a detached ADU $150,000 to $300,000 or more. Your lot, utilities, size and finishes decide where in the range you land.
What does an ADU cost in Sacramento by type?
Here are the starting-point ranges we use when homeowners call. They are estimates for the Sacramento region and include design, permitting and construction. They are not a quote, because the same floor plan can cost very different amounts on two different lots.
| ADU type | Typical range | Typical size |
|---|---|---|
| Junior ADU | $50,000 to $100,000 | Up to 500 sq ft |
| Garage conversion | $80,000 to $150,000 | Existing garage, often 400 to 600 sq ft |
| Attached ADU | $100,000 to $300,000 | Often 500 to 1,000 sq ft |
| Detached ADU | $150,000 to $300,000+ | Commonly up to 1,200 sq ft |
You will see much lower numbers online, often from companies that quote only the box, the building itself, without site work, utilities, permits, design or solar. Ask any builder what is included before you compare.
Why do two similar ADUs cost such different amounts?
The building is only part of the job. The rest is everything that connects it to your property and to the city. Here is what moves the number the most, in roughly the order we see it on Sacramento projects.
- Sewer routing. If the ADU sits lower than the main sewer line or far from it, you may need a long trench or a pump. On older lots in East Sacramento and Land Park, the existing lateral may be clay pipe that needs replacing.
- Electrical capacity. Many homes built before the 1980s have 100 amp panels. A second unit usually needs a panel upgrade, and sometimes a service upgrade from the utility.
- Foundation and slope. Flat lots with good soil are simplest. Slopes in Folsom, Rocklin and El Dorado Hills often mean stepped foundations or retaining walls.
- Size. Larger units cost more overall, though cost per square foot often goes down as size goes up because kitchens and baths are a fixed cost.
- Finishes. Cabinets, counters, flooring and fixtures can swing a budget by tens of thousands of dollars. Our design center lets you see options and price them before you commit.
- Solar. New detached ADUs generally need a solar PV system under the California Energy Code. That is a real line item that some quotes leave out.
- Access. If materials and equipment must go through a narrow side yard by hand, labor goes up. Alley access, common in older Sacramento neighborhoods, helps.
How much are ADU permit and impact fees in Sacramento?
Fees vary by jurisdiction and change often, so we quote them for your address. In general, you can expect plan check and building permit fees based on the project's valuation, school fees in many districts, and utility connection fees from water and sewer providers.
The most important rule for budgeting is the 750 square foot line. ADUs under 750 square feet are exempt from certain impact fees under California law. Above 750, those fees are typically charged in proportion to the size of the main house. Designing a one-bedroom at 740 square feet rather than 800 can save real money without changing how the unit lives.
The City of Sacramento also offers free pre-approved ADU plans in studio, one-bedroom and two-bedroom layouts. Using one can reduce design costs and shorten plan check.
Is a detached ADU worth the higher cost?
It depends on your goals. A detached ADU offers full privacy for both households and generally commands the highest rent. If you already have a sound detached garage, a garage conversion can deliver a similar result for considerably less. If you need space for a family member and do not plan to rent, a junior ADU may be all you need.
Think about the next ten years, not just the build. A unit that houses a parent today and earns rent later has a different value than one you plan to rent immediately.
How do people pay for an ADU?
Most of our clients use one or a combination of these:
- Cash or savings, the simplest path with no financing costs.
- A home equity loan or HELOC against the main house.
- A cash-out refinance, which can make sense depending on your current rate.
- A construction loan or renovation loan that lends against the value after the ADU is complete.
California now lets projected ADU rental income count toward qualifying for some loans. Lender policies differ, so verify with a lender before you rely on it. We are happy to provide plans and a cost breakdown your lender can use.
What should a good ADU quote include?
A complete quote should cover design and 3D renderings, structural engineering, Title 24 energy calculations, permit fees or an allowance, utility connections, foundation, framing, roofing, windows, mechanical, electrical and plumbing, insulation, drywall, finishes, solar if required, and final inspection. If a number looks too good, it usually leaves something out.
Because we design, permit and build under one contract, our pricing covers the whole job. You will not get a design you cannot afford to build, because the builder is in the room from the first sketch.
Frequently asked questions
What is the cheapest type of ADU in Sacramento?
A junior ADU is usually the least expensive, typically $50,000 to $100,000, because it uses space inside the existing home.
How much does a 1,200 sq ft detached ADU cost?
A full-size detached ADU of around 1,200 square feet commonly lands toward the upper end of the $150,000 to $300,000+ range, depending on site and finishes.
Does an ADU under 750 square feet cost less in fees?
Yes. ADUs under 750 square feet are exempt from certain impact fees under California law.
Rules vary by jurisdiction and change often. Call us to confirm what applies to your property. Figures are estimates.