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Madison, AL Accessory Structures: ADU Rules (2026)

Some Restrictions

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

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

Key Facts

Units per lot: One ADU maximum
Detached ADU size cap: 1,000 square feet
Separate sale: Prohibited
Extra parking: One paved 180 sq ft space
Code section: Zoning Ord. 6-5-1.B

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 Alabama under recent ADU streamlining laws. The Madison, AL rules below cover local size, height, and setback requirements.

Summary

Madison's Zoning Ordinance permits one accessory dwelling unit per single-family lot. A detached ADU must be part of an accessory garage, may not exceed 1,000 square feet, and cannot be sold separately from the main home.

No single-family dwelling or lot shall have more than one accessory dwelling unit. Accessory dwelling units detached from the principal dwelling shall be part of an accessory detached garage. A unit may not exceed 1,000 square feet and the total structure (unit and garage) may not exceed 25 percent of the primary dwelling.

View official code

Full Breakdown

Under Zoning Ordinance Section 6-5-1.B, no single-family dwelling or lot may have more than one accessory dwelling unit, and an ADU may not be held in separate ownership or sold apart from the principal dwelling. A detached ADU must be part of an accessory detached garage; the unit may not exceed 1,000 square feet and the total structure (unit plus garage) may not exceed 25 percent of the primary dwelling. It may have only one kitchen and must be architecturally compatible with the main home. One additional paved on-site parking space (at least 180 sq ft) is required, but no new driveway is allowed. The City may inspect the ADU for compliance.

Violations & Fines

Building without required permits or zoning compliance can trigger stop-work orders, permit denial, and code-enforcement action. Contact Planning at 256-772-5630 before starting.

Frequently Asked Questions

Can I rent out and sell my ADU separately?

You may rent it, but Section 6-5-1.B prohibits holding the ADU in separate ownership or selling it apart from the principal dwelling unit.

Does a detached ADU have to be a standalone cottage?

No. A detached accessory dwelling unit must be part of an accessory detached garage, not a freestanding backyard cottage.

Sources & Official References

[1]City of Madison Zoning Ordinance (Sec. 6-5-1.B)

Other rules in Madison

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All Madison rules

How Madison compares: Easiest Cities to Build an ADU·Compare Madison to another location·View the Alabama accessory structures overview

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ADU Rules in Nearby Cities

How other cities in Madison County handle adu rules.

Huntsville, AL

Significant Restrictions