How Much Does It Cost to Build an ADU in Sacramento? (2026 Prices)

The honest answer to "how much does an ADU cost in Sacramento" is a range, and the range is wide because an ADU can be a converted garage or a new two-bedroom house in the backyard. This guide puts the numbers side by side: published starting prices by size, what the City and school district add on top, what changes between a detached, attached, garage conversion and junior ADU, and the decisions that move the total the most.

The short answer

• Construction is most of the money. The City of Sacramento's ADU Resource Center estimates that about 80% of an ADU budget goes to materials and labor and about 20% to design, consulting and permits.
• Our published starting prices for a custom ADU run from $348 per sq ft on a compact 450 sq ft unit down to $288 per sq ft at 1,200 sq ft. Smaller units cost less in total but more per square foot.
• A garage conversion starts lower, from $108,000 on our published pricing, because the slab, walls and roof already exist.
• City fees on the City's own 2026 estimate run from about $5,300 at 749 sq ft to about $14,800 at 1,200 sq ft, before school and sewer fees. Details are in our Sacramento ADU fees and permits guide.
• For a statewide reference point, a UC Berkeley Center for Community Innovation and Terner Center survey of California ADU owners (published 2021) found a median construction cost of $150,000, or about $250 per sq ft. Prices have risen since, so use it as context, not a quote.

Starting prices by size

These are the starting rates published on our ADU models, multiplied out to a total. They are where a standard build begins on a typical lot; site work, finishes and utility runs move the final figure.

ADU size	Typical layout	Starting rate	Starting total
450 sq ft	1 bedroom, 1 bath	$348 / sq ft	about $156,600
750 sq ft	2 bedrooms, 2 baths	$324 / sq ft	about $243,000
1,000 sq ft	3 bedrooms, 2 baths	$312 / sq ft	about $312,000
1,200 sq ft	2 bedrooms	$288 / sq ft	about $345,600

The per-foot price falls as the unit grows because the most expensive parts of any home, the kitchen, the bathrooms and the utility connections, are needed whether the unit is 450 or 1,200 sq ft. Adding a bedroom costs less per foot than the first one did. You can compare the floor plans behind these numbers on our ADU models page.

Cost by ADU type

Detached ADU

A new, freestanding unit in the backyard. It needs everything new: foundation, framing, roof, and utility lines run from the main house. That makes it the most expensive type per project, and the one where site conditions matter most. A long trench from the house to a back corner of a deep lot, or a slope that needs grading, shows up directly in the price.

Attached ADU

Built onto the side or back of the main house. It shares one wall and often a shorter utility run, so it usually sits between a detached unit and a conversion. The trade-off is that the work touches the existing house: the roof line, the shared wall and sometimes the main electrical panel.

Garage conversion

Turning an existing garage into a living unit reuses the slab, walls and roof, which is why it is usually the lowest-cost full ADU. The work goes into insulation, windows, a new floor system over the slab, plumbing for the kitchen and bathroom, and bringing the space up to the energy and building code for living space. State law also limits what the City can charge: an ADU inside an existing structure cannot be required to get a new or separate utility connection, and no connection fee or capacity charge can be imposed for it. Our garage conversion cost guide breaks this type down line by line.

Junior ADU (JADU)

A unit of up to 500 sq ft created inside the existing house, from a bedroom, part of the living space or an attached garage. It can share a bathroom with the main house, which removes the most expensive room from the project, so it is usually the least expensive option. A JADU of 500 sq ft or less owes no impact fee.

For a side-by-side reference, the UC Berkeley survey of California ADUs (units permitted in 2018 and 2019) put median costs at $180,000 for detached units, $150,000 for additions, $100,000 for conversions of space inside the main house and $90,000 for garage ADUs. Those are pre-2020 prices, useful for comparing types rather than budgeting.

What the City and the school district add

Fees are a small share of the total, but they are the part people misjudge, because the rules changed on January 1, 2026.

• Impact fees: under Government Code 66311.5, an ADU with 750 sq ft of interior livable space or less owes no impact fee. Above 750 sq ft, impact fees must be proportionate to the size of the main house.
• School fees: none under 500 sq ft. Larger ADUs pay the district's residential rate, $2.90 to $7.23 per sq ft across the districts in the City's 2026 reference sheet. For a 750 sq ft ADU in Sacramento City Unified that is about $4,035.
• Sewer: set by SacSewer, not the City, so ask for your parcel's figure before you finalize a budget.
• Plans: the City's three Shelf Ready plan sets (367, 559 and 747 habitable sq ft) are free to use, and the optional ADU zoning review has had no fee since July 12, 2026.

The full fee table, with the City's 749, 750 and 1,200 sq ft examples, is in our fees and permits guide.

The costs people leave out

• Utility runs. Sewer, water and electrical trenching from the house to a detached unit is priced by distance and by what is in the way.
• The main electrical panel. A new unit with its own kitchen and heating often means upgrading the main house's panel or service. Whether yours needs it depends on the existing panel, the ADU's loads and any solar, so check it at the first site visit.
• Site work. Slope, trees, soil and access for equipment all land in the foundation and site-work line.
• Design changes after permit. Changing the layout once plans are approved means revised drawings and another review. The City's free Shelf Ready plans avoid design cost entirely but can only be mirrored, not modified.

Four decisions that lower the total

1. Stay at 750 sq ft or under if the layout works. State law removes impact fees at that size.
2. Stay under 500 sq ft for a studio or one-bedroom used by family, and school fees go too.
3. Convert before you build new. A garage or part of the house already has a structure, and a conversion cannot be charged a new utility connection fee.
4. Keep the kitchen and bathroom on one wall and close to the main house's sewer line. Plumbing distance is one of the easiest costs to design out.

Property taxes after you build

Building an ADU does not reassess your whole property. Under California Revenue and Taxation Code sections 70 and 71, the assessor adds a new base value only for the newly built portion; the rest of the property keeps its existing base value.

Paying for it

Most Sacramento homeowners pay for an ADU with home equity, a refinance or a renovation or construction loan, and some lenders can count part of the ADU's future rent when you qualify. The options, and what each one costs you, are compared in our ADU financing guide. For monthly payment examples, see financing.

FAQ

How much does it cost to build an ADU in Sacramento in 2026?

On our published pricing, a custom ADU starts at about $156,600 for a 450 sq ft one-bedroom and about $243,000 for a 750 sq ft two-bedroom, before City, school and sewer fees. A garage conversion starts from $108,000. Your lot, the utility runs and finishes set the final number.

Is a detached ADU more expensive than a garage conversion?

Yes, as a rule. A detached ADU needs a new foundation, structure, roof and utility lines; a conversion reuses the existing slab, walls and roof and cannot be charged a new utility connection fee.

What is the cost per square foot of an ADU in Sacramento?

Our published starting rates run from $348 per sq ft for a compact unit to $288 per sq ft at 1,200 sq ft. Per-foot cost drops as size grows because the kitchen, bathrooms and utility connections are fixed costs.

Are there fees I can avoid?

Impact fees do not apply at 750 sq ft of interior livable space or less, school fees do not apply under 500 sq ft, and the City's Shelf Ready plans and ADU zoning review are free.

Sources: City of Sacramento ADU Resource Center (cost split and Shelf Ready plans), ADU Fee Estimate CDD-0419 (rev. 07-12-2026) and School District Impact Fees CDD-0226 (rev. 09-09-2026); California Government Code 66311.5 (as amended by SB 543, effective January 1, 2026); Education Code 17620; Revenue and Taxation Code 70 and 71; UC Berkeley Center for Community Innovation and Terner Center ADU survey (2021). Starting prices are Result Construction's published rates as of October 2026 and exclude fees. Checked October 2026.