Accessory Structures in Mendocino County, CA (2026)
6 rules for unincorporated Mendocino County, California.
Verified from official government sources
ADU Rules
Mendocino County allows one accessory dwelling unit and one junior ADU per parcel by right on any lot zoned for single- or multi-family homes. Detached units are capped at 1,200 square feet with four-foot side and rear setbacks, and the County must issue a ministerial building permit within 60 days.
Mendocino County ADU Size and Setback Rules
Some RestrictionsMendocino County Code Sec. 20.166.030(B) (Development Standards - Detached Accessory Dwelling Units)
(B)Detached Accessory Dwelling Units.(1)Location. Shall be located on the same lot or parcel as an existing or proposed primary dwelling unit.(2)Size. A detached accessory dwelling unit shall not exceed twelve hundred (1,200) square feet in size, unless constructed in compliance with the provisions of section 20.166.040...(a)Front yard setback: Per the zoning district standard for the primary d...
ADU Impact Fees
A junior accessory dwelling unit in unincorporated Mendocino County is never treated as a separate or new dwelling unit when the County calculates connection fees or utility impact fees, and no new utility connection can be required for it.
Mendocino County JADU Impact Fee Exemption
Light RestrictionsMendocino County Code Sec. 20.166.030(C)(6)(a)-(c) (Utilities - Junior Accessory Dwelling Units)
(a)Whether built as part of a new dwelling or converted from space in an existing dwelling, a junior accessory dwelling unit shall not be considered a separate or new dwelling unit for the purposes of calculating connection fees or County charges for utilities, including water, sewer, power service, or impact fees.(b)No new or separate utility connection between the junior accessory dwelling un...
ADU Owner Occupancy
Building a junior accessory dwelling unit in unincorporated Mendocino County requires the lot owner to live on-site, unless the owner is a government agency, land trust, or housing organization, and a recorded deed restriction locking in that requirement before any permit issues.
Mendocino County JADU Owner Occupancy Rule
Some RestrictionsMendocino County Code Sec. 20.166.030(C)(8)(a),(c) (Owner Occupancy Requirements - Junior ADUs)
(8)Owner Occupancy Requirements for Junior ADUs.(a)The owner of the lot must reside on-site. Owner-occupancy shall not be required if the owner is another governmental agency, land trust, or housing organization.(c)Prior to obtaining a building permit for a Junior Accessory Dwelling Unit, a deed restriction, approved by the County, shall be recorded with the County Recorder's office, which shal...
ADU Rental Restrictions
Mendocino County bans short-term rentals of accessory dwelling units: a junior ADU cannot be sold and cannot be rented for less than 30 days, and any ADU built under the exempt-from-standards path must be deed-restricted to rentals longer than 30 days.
Mendocino County ADU 30-Day Minimum Rental Rule
Some RestrictionsMendocino County Code Sec. 20.166.030(C)(8)(b); Sec. 20.166.045 (Rental Term Restrictions)
(b)A Junior Accessory Dwelling Unit shall not be sold, and rentals for terms shorter than thirty (30) days shall be prohibited. ... The types of accessory dwelling units provided for in this section shall not be required to comply with the development standards included in sections 20.166.030 and 20.166.035 and shall only be rented for a term longer than thirty (30) days. Prior to obtaining a b...
Shed & Carport Rules
A detached garage, storage shed or similar accessory building in unincorporated Mendocino County can rise no more than 15 feet at the ridge and cover no more than 500 square feet before it loses the reduced setback. Qualifying sheds need only a four-foot setback from a rear line without street frontage; anything bigger, taller, or facing a street follows the standard yard setbacks.
Mendocino County Accessory Shed Size and Setback Rules
Some RestrictionsMendocino County Code § 20.152.015(F)
(F)A detached garage, detached storage shed, or similar detached accessory building not exceeding fifteen (15) feet in height at the ridge and five hundred (500) square feet of floor area shall observe a four (4) foot setback from rear property lines that do not have street frontage. Setbacks from property lines having street frontage shall be as otherwise required by this Division.
Tiny Homes
Mendocino County allows Moveable Tiny Homes as a primary dwelling, ADU, or second residential unit in any residential zoning district, capped between 150 and 400 gross square feet, with a 14-foot towing height limit and mandatory ANSI or NFPA certification.
Mendocino County Moveable Tiny Home Rules
Some RestrictionsMendocino County Code Sec. 20.170.010; Sec. 20.170.015(A)(1),(3)
Moveable Tiny Homes may be established as a single-family dwelling, accessory dwelling unit and/or second residential unit in all zoning districts that allow residential dwellings and/or accessory uses, subject to the limitations contained in this Chapter. ... (1)Height. A Moveable Tiny Home shall have a maximum height of fourteen (14) feet when being towed, per California Vehicle Code section ...
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