Everything homeowners ask about building an ADU in Huntsville — answered with 2026 data.
No — under current zoning Huntsville does not allow ADUs. Sec. 73.5 of the Zoning Ordinance (updated to April 1, 2026, still the live text in September 2026) prohibits residential use of any building behind a main building; detached accessory structures may not contain a kitchen (Sec. 10.6.3) or plumbing beyond one laundry sink and/or one toilet (Sec. 3.1). The only sanctioned option is an interior second-kitchen in-law suite: owner-occupied, family or unpaid guests only, no rent (Sec. 10.6). The 2024 legalization file (2024-1506) was deleted from the City Council agenda on June 13, 2024 and nothing has been re-filed as of September 20, 2026. Details: None. Sec. 73.5 ('No building in the rear of a main building on the same lot may be used for residential purposes') bars backyard and garage ADUs citywide, and the ordinance updated to April 1, 2026 lists no ADU use in any district. An interior second kitchen inside the main house is allowed in Residence 1, 1-A, 1-B and 1-C districts (Sec. 10.6.11); a genuine second unit needs a Residence 2, 2-A, 2-B or 2-C lot, where a two-family dwelling is a permitted principal use (Sec. 13.1). See our full Huntsville ADU rules page for the narrow exceptions and what may change.
ADU construction in Huntsville typically costs $95,000-$185,000. The cost per square foot averages $125-$200. Garage conversions are more affordable at $40,000-$95,000, while prefab ADUs cost $70,000-$150,000. Permit fees add Building permit = total contracting price x 0.0055 (0.55%): about $330 on a $60,000 in-law-suite remodel, $825 on a $150,000 addition (City 'Permit Costs' page, read Sept 2026). Trade permits are billed separately. to your budget. See our detailed Huntsville ADU cost guide.
Detached ADUs in Huntsville can be up to N/A: a detached accessory structure cannot be a dwelling. Attached ADUs are limited to No size cap for an interior second-kitchen suite, but it must be inside the dwelling, share at least one interior wall with and be directly accessible from the living areas, and not be separated from them by a garage, breezeway, porch or other non-habitable space. Junior ADUs (JADUs) have a cap of N/A: Huntsville has no JADU or ADU category. The only interior option is the Sec. 10.6 second kitchen, which stays part of the single-family dwelling. Maximum height is N/A for ADUs. Detached accessory structures are capped at 2 stories (Sec. 73.8.1); the Residence 1 district cap for any building is 2.5 stories / 35 ft (Secs. 10.2.8-10.2.9) and 2 stories / 30 ft for a two-family dwelling in Residence 2 (Sec. 13.2.2). You are allowed up to 0 ADUs. One dwelling unit per single-family lot; a second kitchen does not create a second unit and may not show separate meters, two mailboxes or two addresses on a qualifying lot.
Rear setback: N/A for ADUs (rear dwellings prohibited, Sec. 73.5). A non-dwelling accessory structure must sit at least 5 ft from all lot lines and 10 ft from any other structure on the lot (Sec. 73.8.1). Main-building rear yard: 45 ft in Residence 1 (Sec. 10.2.5); 25 ft for a two-family dwelling in Residence 2 (Sec. 13.2.2). Side setback: N/A for ADUs. No accessory structure may be built in any required side yard (Sec. 73.8.1). Main-building side yards: 15 ft each in Residence 1 (Sec. 10.2.6); 5 ft (1 story) or 6 ft (2 stories), 14 ft combined, for a two-family dwelling in Residence 2 (Sec. 13.2.2). Front setback: N/A for ADUs. No accessory structure may be erected in any front yard (Sec. 73.8.1), and on corner lots it may be no closer to a street than the minimum building line (Sec. 73.8.2). Residence 1 front yard: 40 ft, or 50 ft on major arterials (Sec. 10.2.4); Residence 2 two-family: 20 ft / 50 ft (Sec. 13.2.2). Note that garage conversions may be exempt from setback requirements if the existing structure is already within the setback area.
No ADU parking standard exists because no ADU use exists. Off-street parking for dwellings follows the district's parking section (e.g. Sec. 10.3) and Sec. 73.14; confirm the required count for a two-family dwelling with the Zoning Enforcement Office (256-564-8008). Many cities and states have been relaxing ADU parking requirements in recent years. In California, no additional parking is required for ADUs near transit.
Required for a second kitchen: the owner must occupy the home as their legal residence, users must be family (related by blood, marriage or law) or temporary guests who keep a legal residence elsewhere, and no rent or other remuneration may be taken (Sec. 10.6.5). A home with two kitchens may not be used as rental property at all (Sec. 10.6.9). Note that owner-occupancy rules vary by state law — California and several other states have eliminated this requirement for standard ADUs.
The ADU permit review timeline in Huntsville is typically Not published for residential additions or second-kitchen work; confirm with the Inspection Office (256-427-5331). Zoning questions go to the Zoning Enforcement Office, 256-564-8008. Plan check: Standard residential plan review through the Inspection Office's ePlans submittal; no ADU-specific review exists. Confirm requirements at 256-427-5331. Pre-approved plans availability: None. The City has no pre-approved ADU plan program because ADUs are not a permitted use.
Average ADU rental income in Huntsville: 1-bedroom units rent for $1,050-$1,150/month, 2-bedroom units for $1,100-$1,400/month. Short-term rentals: No. ADUs are not legal and a home with a second kitchen cannot be rented at all (Sec. 10.6.9). Expected ROI: N/A: ADUs are prohibited and a second kitchen may earn no rent (Sec. 10.6.9). For a lawful duplex on a Residence 2 lot, HUD FY2026 Fair Market Rent for the Huntsville MSA is $1,136 (1BR) and $1,310 (2BR).
The minimum lot size for an ADU in Huntsville is N/A for ADUs. For context: minimum lot area is 15,000 sq ft in Residence 1 (Sec. 10.2.1), 12,000 in 1-A (Sec. 11.2.1), 7,500 in 1-B (Sec. 12.2.1) and 5,500 in 1-C (Sec. 16.2.1); a two-family dwelling in Residence 2 needs 7,500 sq ft and 60 ft of lot width (Sec. 13.2.2). This applies to detached ADUs — garage conversions and JADUs may have different or no lot size requirements.
Garage conversions are one of the most popular and affordable ADU options. In Huntsville, a garage conversion typically costs $40,000-$95,000. The key advantages are lower cost (no foundation work), potential setback exemptions, and faster permitting. Read our complete garage conversion guide.
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