Can I build an accessory dwelling unit (ADU) on my property in Sacramento, El Dorado, or Placer County?

Few home improvements have arrived with as much momentum as the accessory dwelling unit, or ADU: a second, smaller home on the same property that can house an aging parent, a returning adult child, a caregiver, or a renter. California's state laws and the local ordinances in Sacramento, El Dorado, and Placer counties have made them genuinely attainable.

What state law allows

California law requires cities and counties to approve ADUs ministerially, meaning through a straightforward application rather than a discretionary hearing, when the proposal meets the rules on size, height, setbacks, parking, and design. State rules set baseline allowances, such as an 800 square foot and 16 foot height standard in most cases, and prohibit owner-occupancy requirements in many situations. That baseline is why ADUs went from rare to common across the region.

Local rules differ

Sacramento, El Dorado, and Placer counties each implement ADUs through their own ordinances, with city variations in Folsom, Roseville, El Dorado Hills, and the unincorporated areas. Local rules govern fire setbacks, parking, utility connections, fees, and whether a second detached unit is allowed alongside a converted one. Plans that sail through in one city can stall in another, so the first call should always be to the local planning department with your parcel in hand.

What ADUs are used for

The three most common uses in the region are family housing, caregiving, and income. An attached or detached unit lets an adult child live nearby with independence, gives a parent or caregiver a private space, or produces rental income that can offset the property's costs. For multigenerational families considering how to keep everyone close, the ADU is often the structural answer to the financial and emotional puzzle.

Costs and financing

An ADU is real construction: permits, design, utilities, and labor, with costs that vary widely by size and whether you convert existing space or build new. Financing options include home equity, cash-out refinancing, renovation loans, and specific ADU loan programs. The income an ADU can return, and the caregiving flexibility it buys, is often what makes the math work, but run the full cost before you pour concrete.

Start with the local office

Begin with the free, official step: call the city or county planning department, describe your lot and your idea, and ask what applies. Then talk to an architect or ADU design-build firm that has done projects in your jurisdiction, and a lender about the financing. With approvals solid, the ADU becomes a real estate asset that can reshape the family's options for decades, which is why it is worth planning properly.