In plain words

Kentucky has no state law that makes towns allow ADUs. An ADU, or accessory dwelling unit, is a small second home on the same lot as a house. It might be a backyard cottage, a garage apartment, or a suite inside the house. In Kentucky, each city or county decides through its zoning. Zoning is the local rulebook for what can be built where. So the answer depends on exactly where your property is. Lexington allows one ADU on any lot with a single-family house. It can be up to 800 square feet, and the owner does not have to live there. Louisville Metro also allows one ADU per house lot, but the owner must live in the house or the ADU. That is called an owner-occupancy rule. A 2025 state law adds a twist in Jefferson County, which includes Louisville. There, some lots have a house and an ADU in a single-family zone. Those homes can only be rented if the owner mainly lives on the lot. Lawmakers filed bills in 2025 and 2026 to make every town allow ADUs. Both died without a vote. Outside the big cities, rules vary widely, and septic and sewer approval can be the real limit. Before you plan, check your city or county zoning code, your deed and any HOA rules. You may be able to build only if local rules and your property allow it.

The rules at a glance

State ADU lawNo. Each city, town or county decides.
Owner living on siteTowns may require the owner to live on the property.
ParkingState law doesn’t set this. Louisville Metro applies its normal off-street parking rules; Lexington requires no extra parking space for an ADU.
SizeState law doesn’t set this. Louisville Metro caps an ADU at 800 sq ft or 30% of the main house, whichever is greater; Lexington caps it at 800 sq ft and at the greater of 625 sq ft or half the main house.
Lot size and setbacksState law doesn’t set this. Each city or county sets setbacks and lot rules; Louisville applies accessory-structure setbacks (typically 5 ft rear, 2 ft side) and Lexington has no minimum lot size.
FeesState law doesn’t set this. Permit, utility and sewer fees are set locally.
Short-term rentalsState law doesn’t set this. Louisville Metro bars short-term rental of an ADU without a conditional use permit; Lexington lets an ADU be a short-term rental only if it also meets its short-term rental rules (Zoning Ordinance Article 3-13).

What to do next

  1. Find out which planning unit covers your property (a city, a county, or a joint city-county planning commission); this decides which zoning code applies.
  2. Look up your zoning district and read the local ADU or accessory-dwelling rules, or call the planning office and ask what is allowed on your lot.
  3. If you are in Jefferson County and might rent either unit, plan for the 2025 state rule that the owner must mainly live on the lot.
  4. Read your deed and any HOA covenants; private restrictions can ban a second unit even where zoning allows one.
  5. If you are on septic or a small sewer system, ask the local health department or sewer district early whether it can serve a second unit.
  6. Get zoning approval and building permits before construction starts.

What your town still decides

Kentucky has no law that makes cities or counties allow ADUs. Local planning units adopt zoning under KRS Chapter 100, and each one decides whether ADUs are allowed, where, how big, and whether the owner must live on site. The one state rule aimed at ADUs (2025 SB 129) applies only in Jefferson County and pushes in the other direction: there, a house-plus-ADU lot in a traditional single-family zone can be rented only if the owner mainly lives on the lot. That state rule covers every city in Jefferson County, not just Louisville Metro's own zoning area. Louisville Metro already required owner occupancy under its own code. Lexington-Fayette is an urban county government, not a consolidated local government, so SB 129's rental rule does not reach it, and Lexington dropped its own owner-occupancy rule in December 2023. Bills that would have made every town allow ADUs were filed in 2025 (HB 576) and 2026 (HB 203) but never got a committee vote. Private deed restrictions and HOA rules can still ban ADUs; Louisville's own guidance says its ADU rules do not override them.

Examples of local rules

  • Louisville Metro (Jefferson County): Ordinance 92, Series 2021 (Land Development Code Sec. 4.3.27) allows one attached or detached ADU on a single-family lot in single-family zones. Size is capped at 800 sq ft or 30% of the main house, whichever is greater, and the ADU must sit beside or behind the house. The owner must live on the property, short-term rental needs a conditional use permit, and normal parking rules apply. The city offers three free pre-approved ADU plan sets paid for by an AARP grant. Some small cities inside Jefferson County with their own zoning have not adopted these standards. Source
  • Lexington-Fayette Urban County: ADUs were first approved in October 2021. A December 7, 2023 update allowed newly built detached ADUs and removed both the owner-occupancy rule and the required deed restriction. One ADU is allowed on any lot with a single-family detached house, up to 800 sq ft and no more than the greater of 625 sq ft or half the main house. No extra parking is required, at most two people plus any related children may live in the unit, and a pre-application meeting and a zoning compliance permit from the Division of Planning come before the building permit. Source

What we’re still confirming

  • SB 129 lets a house-plus-ADU lot in a Jefferson County single-family zone be rented only if the owner mainly lives there; how it applies to new leases on ADUs that already exist isn't clear yet.

Laws, bills and citations

The laws behind this (1)
  • Owner-residence rule for renting ADUs in Jefferson County (Louisville Metro) (2025 Ky. Acts ch. 56 (SB 129), Sections 3 and 4 (new sections of KRS Chapters 100 and 383), signed March 24, 2025, in effect June 27, 2025). This law limits ADUs rather than opening the door to them, and it only applies in Jefferson County, the one county that contains a consolidated local government (Louisville Metro). For leases signed after the law took effect, a lot with a house plus an ADU in a zone that did not allow multifamily homes on January 1, 2025 can only be rented out if the owner mainly lives in the house or the ADU on that lot. It also defines an ADU in state law. In the same county, a multifamily project in those zones that would slow fire or ambulance response or noticeably worsen nearby traffic must go through a full rezoning vote. Read it
Proposed and failed bills (5). None of these is law.
  • HB 203 (2026 Regular Session): died as of October 3, 2026. Would have made every planning unit allow one ADU in all residential zones, with no rules stricter than those for a single-family home and no fees beyond a one-time $250 charge. Towns could still require notice of construction, limit lots to one ADU and ban short-term rental use. It was sent to the House Local Government Committee on January 14, 2026 and got no further action before the session ended on April 15, 2026. Bill page
  • HB 576 (2025 Regular Session): died as of October 3, 2026. An earlier version of the same idea: ADUs allowed in all residential zones, one per lot, a one-time $250 fee cap, and local power to ban short-term rental use. It was sent to the House Local Government Committee on February 25, 2025 and died when the session ended on March 28, 2025. Bill page
  • HB 18 (2025 Regular Session): died as of October 3, 2026. An earlier vehicle for the Jefferson County rental rule: in traditional single-family zones in a county with a consolidated local government, a house-plus-ADU lot could be rented only if the owner lived on the lot. It passed the House 63-18 on March 11, 2025, then sat in the Senate State and Local Government Committee until the session ended. The same rule became law through SB 129. Bill page
  • HB 102 (2024 Regular Session), the HOME Act: died as of October 3, 2026. A broad housing bill that would have told local governments to make room for multifamily housing, ADUs, tiny homes and manufactured homes, ease minimum home-size, parking and design rules, and speed up permits. It sat in the House Local Government Committee from January 9, 2024 and died with the session. Bill page
  • SB 9 (2026 Regular Session): died as of October 3, 2026. A large housing bill (housing development districts, faster plan reviews, parking and permit limits). It did not mention ADUs. Both chambers passed different versions, and the conference committee reported on April 15, 2026 that it could not agree, so the bill died. Bill page

Sources

  1. 2025 Ky. Acts ch. 56 (SB 129), Sections 3 and 4 (new sections of KRS Chapters 100 and 383) · official source
  2. SB 129 (2025 RS) bill record and action history · official source · checked 2026-10-03
  3. Kentucky LRC, Normal Effective Dates (2025 RS: June 27, 2025; 2026 RS: July 15, 2026) · official source · checked 2026-10-03
  4. HB 203 (2026 RS) bill record · official source · checked 2026-10-03
  5. HB 576 (2025 RS) bill record · official source · checked 2026-10-03
  6. HB 18 (2025 RS) bill record (passed House, died in Senate committee) · official source · checked 2026-10-03
  7. HB 102 (2024 RS) bill record · official source · checked 2026-10-03
  8. SB 9 (2026 RS) bill record · official source · checked 2026-10-03
  9. HB 617 (2026 RS) bill record (planning and zoning; no ADU provisions) · official source · checked 2026-10-03
  10. 2026 RS subject index: Planning and Zoning · official source · checked 2026-10-03
  11. 2025 RS subject index: Planning and Zoning · official source · checked 2026-10-03
  12. 2024 RS subject index: Planning and Zoning · official source · checked 2026-10-03
  13. 2023 RS subject index: Planning and Zoning · official source · checked 2026-10-03
  14. 2026 RS subject index: Housing, Building, and Construction · official source · checked 2026-10-03
  15. 2026 RS session record (adjourned sine die April 15, 2026) · official source · checked 2026-10-03
  16. 2025 RS session record (adjourned sine die March 28, 2025) · official source · checked 2026-10-03
  17. Louisville Metro Office of Planning, Accessory Dwelling Units (ADU) · official source · checked 2026-10-03
  18. Imagine Lexington, Accessory Dwelling Units (zoning reform page) · official source · checked 2026-10-03
  19. Lexington-Fayette Urban County Government, What's the Scoop on ADUs (updated Dec. 7, 2023) · official source · checked 2026-10-03
  20. Lexington-Fayette Urban County Government, How to ADU (application process) · official source · checked 2026-10-03

This is general information, not legal advice. Your town, village, city or county decides what can be built on your property. If something here looks out of date, email the team.