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DeKalb County, GA Accessory Structures: ADU Rules (2026)

Some Restrictions

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

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

Key Facts

Min lot size: 10,000 sq ft
Max ADU size: 900 sq ft heated
Height cap: 24 feet
ADUs per lot: One maximum
Detached ADU location: Rear yard required

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 Georgia under recent ADU streamlining laws. The DeKalb County, GA rules below cover local size, height, and setback requirements.

Summary

Unincorporated DeKalb allows attached, detached or converted accessory dwelling units by right on lots of at least 10,000 square feet, capped at 900 square feet and 24 feet tall.

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

Attached and detached accessory dwelling units are permitted by right, subject to the following:1.The minimum lot size shall be ten-thousand (10,000) square feet.2.The accessory dwelling unit shall conform to applicable standards of the state and county building codes for residential units as principal uses.3.The property owner, who shall include titleholders and contract purchasers, must occupy either the principal dwelling unit or the accessory dwelling unit as their residence, and possess a homestead exemption.4.The appearance of the accessory dwelling unit shall be similar to that of the principal residence.5.Only one (1) accessory dwelling unit of any type shall be permitted on a lot.6.Prior to issuance of a building permit for an accessory dwelling unit, an applicant must provide evidence to the director of planning showing that existing or proposed septic tank facilities, as applicable, are adequate to serve both the principal dwelling and the accessory dwelling unit.7.Any detached accessory dwelling unit shall be located in the rear yard.8.A second kitchen facility may be constructed and used within a single-family residence.9.Paved off-street parking shall be provided for one (1) additional vehicle.10.Accessory dwelling units shall not exceed nine hundred (900) square feet of heated floor area and shall not exceed twenty-four (24) feet in height.

Source: Dekalb County Municipal CodeView official code

Full Breakdown

DeKalb's zoning code permits one accessory dwelling unit per single-family lot, attached, detached, or built from converted space like a basement or attic, as a by-right use once the lot hits 10,000 square feet. A detached ADU must sit in the rear yard, its heated floor area can't top 900 square feet, and it's capped at 24 feet tall. The design has to look similar to the main house, off-street parking for one extra vehicle is required, and entrances can't face the nearest property line. This applies only to unincorporated DeKalb; incorporated cities set their own ADU standards.

Violations & Fines

An ADU that exceeds the size or height cap, or is built without the required rear-yard placement, is a zoning violation the planning and sustainability department can require be corrected or removed.

Frequently Asked Questions

Can I build a detached garage apartment in unincorporated DeKalb County?

Yes, as an accessory dwelling unit by right on a lot of at least 10,000 square feet, capped at 900 square feet and 24 feet tall, located in the rear yard, § 4.2.3(C).

How many accessory dwelling units can one DeKalb County lot have?

Only one, of any type, attached, detached, or converted from existing space, per § 4.2.3(C)(5).

Sources & Official References

[1]DeKalb County Code of Ordinances § 4.2.3(C) (Article 4)

Other rules in DeKalb County

Parking Rules: Street Parking LimitsSome Restrictions Shed & Carport RulesSome Restrictions ADU Owner OccupancySome Restrictions Noise Ordinances: Decibel LimitsSome Restrictions Noise Ordinances: Barking DogsSome Restrictions Noise Ordinances: Aircraft NoiseLight Restrictions Parking Rules: Preferential Parking DistrictsSome Restrictions Parking Rules: Commercial & Oversized VehiclesSignificant Restrictions

All DeKalb County rules

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

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