St. Tammany Parish, LA Accessory Structures: ADU Rules (2026)
ADU rules in St. Tammany Parish, LA, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.
Key Facts
- Max habitable space
- 1,000 sq ft on most lots
- Large-lot max
- 2,500 sq ft / 7.5% of lot
- Location rule
- Must sit behind the main structure
- Setback rule
- Meets district's primary setbacks
- Corner lot rule
- Front setback vs. closest street
- Governing section
- UDC Sec. 600-6.2
- Max fine
- $500 per violation, per day
Summary
Unincorporated St. Tammany Parish allows one garage apartment or guest house per lot in every residential zoning district under UDC Sec. 600-6.2, capped at 1,000 square feet of habitable floor space, or up to 2,500 square feet (7.5 percent of the lot) on parcels over an acre. The unit must sit behind the main house and meet the district's primary setbacks, including the front setback on corner and through lots.
Garage apartment or guest houses are permitted in all residential districts and shall not exceed 1,000 square feet of habitable floor space. For lots over 1 acre in area, a guest house may be scaled to 7.5 percent of the total lot provided the guest house does not exceed 2,500 square feet of habitable floor space. All guest homes must meet the minimum primary setbacks required within the respective zoning classification for which the property is within. All guest homes must be located behind the main structure. Where a guest home is proposed to be located on a corner lot or through-lot, the guest home must meet the front yard setbacks against the closest adjacent street.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 12 Update 2).
Full Breakdown
Sec. 2 of the Unified Development Code is the accessory-use standard governing garage apartments and guest houses parish-wide. It permits one in any residential district, but caps habitable floor space at 1,000 square feet. 5 percent of the total lot area, still subject to a hard ceiling of 2,500 square feet of habitable space. Every guest home has to meet the minimum primary setbacks that apply to the main house within its zoning classification, and it must be located behind the main structure rather than in front of it.
On a corner lot or through-lot, the guest home also has to satisfy the front-yard setback measured against whichever adjacent street is closest. The UDC's definitions section, Sec. 100-5, ties these size limits to related terms: an "Accessory Dwelling Unit or ADU" is a smaller, independent dwelling on the same lot as a detached single-family home, which can be internal, attached, or a detached new or converted accessory structure; "Apartment, Garage" is a building under 1,000 square feet with a second story usable for residential purposes; and a "Guest Home" is an accessory structure used as temporary housing. Sec. 2 separately confirms that private garages and other accessory structures, without the residential floor space, are permitted in all residential districts.
Violations & Fines
A garage apartment or guest house built oversized, in front of the main house, or without the required setbacks is a zoning violation the Department of Planning and Development can cite under the parish's general enforcement code, Sec. 2-551 through Sec. 2-559. The hearing officer may assess a fine of up to $500.00 per violation, the same $500.00 again for each day the violation continues, plus a mandatory administrative cost of at least $100.00.
Frequently Asked Questions
How big can a garage apartment or ADU be in St. Tammany Parish?
Where on my lot can I put a guest house?
What's the difference between an ADU and a private garage?
Is a garage apartment allowed in every residential zoning district?
Sources & Official References
Other rules in St. Tammany Parish
How St. Tammany Parish compares: Easiest Cities to Build an ADU·Compare St. Tammany Parish to another location·View the Louisiana accessory structures overview
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