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Greene County, MO Accessory Structures: ADU Rules (2026)

Some Restrictions

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

ADU rules in Greene County, MO, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.

Key Facts

Living area cap: 1,000 sq ft in accessory structure
Rear setback: 10 feet minimum
Distance from main house: 10 feet minimum
Applies to: Unincorporated county land only
Over the cap: Board of Zoning Adjustment variance

ADU Eligibility Quick-Check

An Accessory Dwelling Unit (ADU) is a smaller, independent living unit on the same lot as a single-family home: converted garages, detached cottages, basement or attic conversions, and attached additions all qualify. Most states have streamlined ADU permitting since 2020, but local rules still control size, height, and setback.

Is your lot zoned single-family or multi-family residential?
Does your lot have at least 1,200 sq ft of buildable space?
Is your existing home owner-occupied (in most states this is not required, but some require it for ADU permits)?
Will the ADU stay under your state's size cap (commonly 850-1,200 sq ft for detached)?
Can you provide one off-street parking space (waived in many states within 0.5 mi of transit)?

If you answered 'yes' to most of these, you likely qualify in Missouri under recent ADU streamlining laws. The Greene County, MO rules below cover local size, height, and setback requirements.

Summary

Unincorporated Greene County zoning lets homeowners add a garage apartment, guest house, or servant's quarters as an accessory structure, but caps living area at 1,000 square feet and applies standard setback rules.

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

g. Living quarters; h. Garage/living area combinations; i. Guest house, servant’s quarters, or rooms for guests in an accessory building, where structure must comply with adopted building codes and other adopted standards; ... 4. Living area in an accessory structure will be limited to one thousand (1,000) square feet.

Source: Greene County Resource Management — Building RegulationsView official code

Official source re-checked September 7, 2026: the cited page had not changed since it was quoted.

Full Breakdown

The county's zoning regulations list "garage/living area combinations" and guest houses or servant's quarters as permitted accessory structures, provided they meet adopted building codes. Living area inside any accessory structure is capped at 1,000 square feet, and the structure must still meet the same setback, spacing, and side-yard rules as other accessory buildings. Exceeding the size cap or building in a restricted yard requires a variance from the Board of Zoning Adjustment. This applies only to unincorporated county land. Springfield, Republic, Willard, Strafford, Ash Grove, and Battlefield enforce their own separate municipal codes, not this document.

Violations & Fines

Building a garage apartment or guest house with more than 1,000 square feet of living area, or placing it in a yard where accessory buildings aren't allowed on lots under three acres, requires a Board of Zoning Adjustment variance under Section 8(F) before construction can proceed.

Frequently Asked Questions

Can I build a garage apartment on my Greene County property?

Yes, on unincorporated land. The zoning regs permit garage/living-area combinations and guest houses as accessory structures, capped at 1,000 square feet of living area and subject to standard setbacks.

Do these rules apply if I live in Springfield?

No. Springfield, Republic, Willard, Strafford, Ash Grove, and Battlefield each have their own municipal codes; the county zoning regulations govern only unincorporated Greene County.

Sources & Official References

[1]Greene County Zoning Regulations (county resource management page)

Other rules in Greene County

Shed & Carport RulesSome Restrictions Parking Rules: RV & Boat ParkingSome Restrictions Noise Ordinances: Decibel LimitsHeavy Restrictions Parking Rules: Driveway RulesSome Restrictions Parking Rules: Loading ZonesSome Restrictions Parking Rules: Commercial & Oversized VehiclesSome Restrictions Parking Rules: Abandoned VehiclesSome Restrictions

All Greene County rules

How Greene County compares: Easiest Cities to Build an ADU·Compare Greene County to another location·View the Missouri accessory structures overview

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ADU Rules in Cities Across Greene County

Springfield, MO