5 county-level rules, plus city-specific rules for 3 cities in Placer County, California.
Verified from official government sources
In unincorporated Placer County, residential parcels may have one primary dwelling, one accessory dwelling unit (ADU) and one junior ADU. Detached ADUs may reach 1,200 sq ft; attached ADUs up to 50% of the primary dwelling. There is no minimum parcel size, setbacks are 4 ft from side and rear lot lines, and parking is capped at one space per ADU.
Placer County Code § 17.56.200 (Accessory and junior accessory dwelling units)
One ADU and one Junior ADU are allowed per parcel in addition to the primary dwelling. Detached ADUs may be up to 1,200 sq. ft. The minimum required setback for a new construction ADU on a single-family property is 4 feet from the rear and interior side property lines.
In unincorporated Placer County, a one-story detached accessory building used as a tool shed, storage shed or playhouse does not require a building permit if its floor area does not exceed 120 square feet. Even exempt sheds must meet zoning setbacks measured under the Placer County Zoning Ordinance, and any electrical, mechanical or plumbing work requires a permit.
Placer County FAQ (Building Services) and Placer County Code § 17.56.020
One-story detached accessory buildings used as tool and storage sheds, playhouses, and similar uses, provided the floor area does not exceed 120 square feet, do not require a Building Permit. Contact the Planning Division for required setbacks from property lines for such structures.
Converting a garage into living space in unincorporated Placer County requires a building permit and must meet building, energy and zoning standards. A garage converted into an accessory dwelling unit is a state-favored ADU pathway under Placer County Code 17.56.200; conversion ADUs are exempt from added parking. Replacement of any displaced required parking may apply for non-ADU conversions.
Placer County Code § 17.56.200 (consistent with CA Gov. Code § 65852.2)
When a garage, carport, or covered parking structure is converted to an accessory dwelling unit, the local agency shall not require that those off-street parking spaces be replaced. Additional parking is not required for junior ADUs or ADUs that are converted from a garage, carport or other covered parking space.
A carport is a roofed accessory structure in unincorporated Placer County and generally requires a building permit, unlike a small storage shed. Carports must meet the setback and height standards of the Placer County Zoning Ordinance (Chapter 17) for the parcel's zone district. The Planning Division sets allowable setbacks, and additional conditions may apply in high-fire areas and the Tahoe Basin.
Placer County has no separate tiny-home ordinance. A tiny home on a permanent foundation is treated as a dwelling or accessory dwelling unit under Placer County Code 17.56.200 and must meet building code; movable tiny homes on wheels are regulated as recreational vehicles or manufactured homes and generally cannot be used as a permanent dwelling outside approved parks.
3 cities in Placer County have their own accessory structures rules. Each link goes to that city's dedicated page with code citations.
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