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Mendocino County, CA Building Setbacks & Zoning: Lot Coverage Limits (2026)

Some Restrictions
Compiled from the official code textEditor Martyn O'NeillLast verified September 2026

Key Facts

Coverage, under 2 acres
20% maximum
Coverage, 2 to 5 acres
15% maximum
Coverage, over 5 acres
10% maximum
District
AG - Agricultural (Coastal Zone)
Companion yard setback
50 ft front/rear/side, Sec. 20.356.030

Summary

In Mendocino County's Coastal Zone Agricultural (AG) District, Zoning Code Section 20.356.045 caps how much of a parcel can be covered with buildings on a sliding scale tied to parcel size: twenty percent on parcels under two acres, fifteen percent on parcels from two to five acres, and ten percent on parcels over five acres.

These county ordinances apply to unincorporated areas of Mendocino County. Incorporated cities within the county may have their own rules that take precedence over county-level regulations.

Twenty (20) percent for parcels less than two (2) acres in size. Fifteen (15) percent for parcels from two (2) acres to five (5) acres in size. Ten (10) percent for parcels over five (5) acres in size.

View official code

Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 75).

Full Breakdown

045, and the RR, RMR, SR, RV and C Districts further down the same chapter series. For AG-zoned parcels, coverage is limited to twenty percent for parcels under two acres, dropping to fifteen percent for parcels between two and five acres, and to ten percent for parcels over five acres, so larger agricultural holdings must leave proportionally more open land as parcel size increases. "Lot Coverage" is defined in the Coastal Zoning Code's definitions chapter as the percentage of gross lot area covered by all buildings and structures on a lot, including decks and porches, whether covered or uncovered, and all other projections except eaves.

Because AG District land sits within the Coastal Zone, any development that would push a project toward its coverage ceiling, such as a new barn, residence or accessory structure, also needs a coastal development permit, and the California Coastal Commission retains appeal jurisdiction over the county's permit decision under the Coastal Act. 035), so a project must clear both the yard setbacks and the percentage-based coverage cap.

Violations & Fines

Exceeding the AG District's lot coverage cap is a permit-condition violation under the Coastal Zoning Code's enforcement chapter, Section 20.552.015: each day of noncompliance counts as a separate offense, subject to the sanctions in Section 20.552.010. The Mendocino County Planning and Building Services Department, or the County Counsel's office acting under Section 20.552.025, may declare the overbuilt structure a public nuisance and pursue abatement, removal or a court injunction.

Frequently Asked Questions

What is the maximum lot coverage on agricultural land in Mendocino County's Coastal Zone?
Section 20.356.045 of the Coastal Zoning Code sets a sliding scale for AG-zoned parcels: twenty percent maximum coverage on parcels under two acres, fifteen percent on parcels from two to five acres, and ten percent on parcels larger than five acres. Coverage includes all buildings, decks and porches, covered or not, other than eaves.
Does a coastal development permit apply on top of the lot coverage limit?
Yes. AG District land sits within the Coastal Zone, so a project that meets the Section 20.356.045 coverage cap still needs a coastal development permit, and the California Coastal Commission holds appeal rights over the county's decision under the Coastal Act's permit and appeal provisions.
What setback applies to buildings in the AG District besides the lot coverage cap?
Section 20.356.030 requires a fifty-foot front, rear and side yard on AG-zoned parcels. Nonconforming parcels under five acres get a reduced twenty-foot yard under Section 20.356.035, but both setbacks apply independently of, and in addition to, the percentage-based lot coverage limit in Section 20.356.045.

Sources & Official References

Other rules in Mendocino County

All Mendocino County rules

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