Side by side · Kentucky

Compare ADU rules across Kentucky

Flexible on where you build? The same backyard cottage can be routine in one city and impossible in the next. This table puts 20 Kentucky cities side by side so you can shortlist the friendly ones before reading a single ordinance, or narrow it to just the cities you are deciding between. Every value is summarized from the city's own code; open a city's page for the full notes, citations, and fine print.

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CityDetached ADUAttached / internalMax sizeOwner occupancyExtra parkingApproval
Ashland

Ashland's zoning code allows a second dwelling on a single-family lot in one district only: in R-E Residential Estate, residential accessory uses "may also include secondary dwelling units (guest house, caretaker's quarters)" as a by-right accessory use. Every other district keeps the general rule of one single-family building plus its accessory structures per zoning lot, and the code has no accessory dwelling unit, accessory apartment or garage apartment use. R-E is a large-lot estate district (20,000 sq ft minimum lot, 100 ft width) meant for remote or steep land, so most city lots in R-12, R-6, R-5 and R-4 cannot add a detached unit.

Ordinance read October 2026

The code has no attached or internal ADU use. In R-E the secondary dwelling unit allowance in § 157.040(A)(9) does not say whether the unit must be detached, so a guest or caretaker unit may be possible within or attached to the house there. Elsewhere the only route to a second unit inside a house is converting it to a two-family dwelling (duplex): permitted by right in R-5, R-4 and B-3 (on 2,500, 2,000 and R-4-equivalent lot area per unit), a Board of Zoning Adjustment conditional use in R-6 limited to lots at the fringe abutting incompatible uses, and not allowed in R-12. A duplex is two principal units, not an accessory unit.

Ordinance read October 2026

No unit size cap; subordinate to the principal dwelling; R-E: 25% lot coverage, 45 ft heightNot required1 off-street space per dwelling unitPermitted use
Bowling GreenAllowedAllowed50% of the principal structure's floor area; 2 bedrooms maxRequired1 additional spacePermitted use
CovingtonAllowedAllowed1,000 sq ft or 50% of the principal dwelling's total square footage, whichever is less; carriage house footprint also capped at 50% of the principal building's footprint or 1,000 sq ft, and its height must be below the principal structure

Only detached ADUs carry an owner-occupancy rule, and only in some districts: in the RR, SR and mixed-use districts the owner must live in either the principal residence or the ADU. Among the districts that allow Carriage Houses, that covers RR, SR and TUR (a mixed-use district under Sec. 02.04.3), but not SU. Integrated ADUs have no owner-occupancy requirement in any district. The rule is written as a continuing use standard, not a one-time application test.

Ordinance read October 2026

1 space in RR and SR; none in SU, TUR, CRM and DTC (maximum 1 space per ADU)Permitted use
ElizabethtownAllowedAllowed800 sq ft or 25% of the principal dwelling's floor area, whichever is greater; zone height limit (35 ft in R-1 to R-4)Not required1 additional off-street space in R-1 to R-6Permitted use
Erlanger

Erlanger's zoning ordinance lists the accessory dwelling unit as a conditional use in every residential district (R-LLS, R-CVS, R-CPS, R-M, R-MF) and the MHP district, so a detached backyard or over-garage unit needs a conditional use permit from the Erlanger Board of Adjustment; it is a permitted use only in the MU (Mixed Use) district. §4.05.J.2.f allows the unit to be attached or detached, one per single-family or two-family lot, and only on lots of at least 5,000 square feet. A detached unit follows the setbacks for accessory structures and counts toward the cumulative accessory floor area limits (in R-CVS, R-CPS and R-M, 10 percent of the rear yard and never more than the primary structure's floor area).

Ordinance read October 2026

An attached or internal ADU takes the same route as a detached one: a conditional use permit from the Board of Adjustment in every residential district, by right only in MU. Attached units must keep the primary dwelling's front to a single entrance (a second entrance may go on the side or rear) and must meet the setbacks for primary structures. The 5,000 square foot minimum lot and one-unit-per-lot limit apply.

Ordinance read October 2026

800 sq ft or 75% of the primary dwelling's living area, whichever is less; no taller than the primary structure; 5,000 sq ft minimum lotRequired1 off-street space for the ADU

In every residential district the ADU is a 'C' use, which §4.04.C.2 defines as a conditional use that must be approved by the Board of Adjustment, which may impose additional conditions under KRS 100.237; §13.08 gives the Board that power. Only in the MU (Mixed Use) district is the ADU a permitted use by right. Erlanger's Board of Adjustment holds public hearings on these requests (BOA-24-0008, 412 Hallam Avenue, 2024). PDS of Kenton County then issues zoning and building permits.

Ordinance read October 2026

Florence

Florence zones under the Boone County Zoning Regulations, which define an accessory dwelling unit to include one inside a structure accessory to a single-family home. In every ordinary residential district (RS, SR-1, SR-2, SR-3, R-1F, UR-1, UR-2, UR-3) a unit in an accessory structure is a conditional use that needs a permit from the Board of Adjustment after a public hearing, and the lot must be at least 1.5 times the district's minimum lot area. Only the RSE district (and the A-1 and A-2 agricultural districts) list the use as a plain accessory use. The unit is allowed only with a detached single-family home that is not a patio home, one per lot.

Ordinance read October 2026

Allowed35% of the principal structure's floor area; detached units also need a lot at least 1.5 times the district minimumNot required1 additional off-street space

An ADU inside the house is an accessory use approved with a zoning permit from the Planning Commission's Zoning Administrator, decided within seven working days. An ADU in an accessory structure is a conditional use in Florence's ordinary residential districts, so it needs a conditional use permit from the Florence Board of Adjustment after a public hearing under KRS 100.237, followed by a zoning permit. In RSE and the agricultural districts both types are accessory uses.

Ordinance read October 2026

Frankfort

Frankfort allows accessory dwelling units only as a conditional use in the two historic overlay-style districts: the Special Historic (SH) district (§4.403 L) and the Special Capitol (SC) district (Conditional Uses list under §4.412, item L). Ord. 14, 2025 Series (adopted 8-25-2025) added the ADU definition, which covers new stand-alone accessory structures and converted accessory structures, and these two use listings; staff called it a stopgap ahead of the full development code rewrite. The ordinary single-family districts (RE, RA, RB, RC) and every other district in the §4.05 land use table list no ADU use, so a backyard unit there is not allowed.

Ordinance read October 2026

The same definition counts converted portions of an existing home (internal ADUs) and additions (attached ADUs) as accessory dwellings, and they get the same treatment: a conditional use in the SH and SC districts only. Outside those districts the only route to a second unit in a house is a two-family dwelling, which the land use table permits by right in RD, RL, RH, CL, CH and UM, by conditional use in RC, PO and CG, and in RS only with Board of Zoning Adjustments approval (note 4); that is a duplex, not an ADU, and is not available in the RE, RA or RB single-family districts.

Ordinance read October 2026

No numeric cap; ARB sets bulk in SH and SC; 45 ft max heightNot requiredNone specific to ADUs; SH and SC residential parking may be on-street, at half the usual 2 spaces per unit

Every ADU needs a conditional use permit decided at a public hearing. Article 19 sends conditional uses to the Board of Zoning Adjustments under its general criteria (§19.01), while the SC text says the Architectural Review Board 'may grant conditional use permits' for the listed uses, and in both districts the ARB also reviews construction (a certificate of appropriateness). Ord. 14, 2025 adds no ADU-specific criteria, so the general §19.01 findings apply, followed by a building permit.

Ordinance read October 2026

GeorgetownNot allowed

There is no attached or internal ADU use either. The only route to a second unit inside or attached to a house is a duplex (defined in §2.1 as 'a structure containing two dwelling units, each of which has direct access to the outside'), which is a permitted use only in R-2 Medium Density Residential (§4.3.5.1.b) and R-3 High Density Residential (§4.3.6.1.a, all residential uses meeting lot dimension standards), subject to the Schedule of Dimension and Area Regulations and the 12 (R-2) or 16 (R-3) units per gross acre density caps. R-1A, R-1B and R-1C permit only single-family dwellings; R-1B and R-1C (and R-2, R-3) do allow renting up to three sleeping rooms as an accessory use, but a sleeping room by definition lacks separate housekeeping and is not a dwelling unit.

Ordinance read October 2026

No ADU size standard (no ADU use in the city ordinance)Not requiredNo ADU standard; a second unit falls under the residential table (1.5 spaces for a studio or 1 bedroom, 2.5 for 2 or more bedrooms)Permitted use
HendersonNot allowed

No district allows an accessory apartment inside a single-family home. The only route to a second unit in a house is a two-family dwelling (duplex), which §4.06 permits by right in R-2, R-3 and R-4, in a PUD and in the Audubon Residential district, subject to the district's two-family minimums: 10,000 sq ft and 75 ft of width in R-2, 9,000 sq ft in R-3 and 8,000 sq ft in R-4. The R-1 and R-5 single-family districts do not allow two-family dwellings, so a lot there would need a rezoning (Planning Commission hearing and City Commission ordinance).

Ordinance read October 2026

No ADU size cap (no ADU use); duplex follows district bulk rules (R-2: 10,000 sq ft lot, 40% coverage, 30 ft height); accessory buildings 1 story/14 ft, combined floor area no larger than the houseNot required2 spaces per dwelling unitPermitted use
HopkinsvilleNot allowed

There is no ADU use, but a house can lawfully hold a second unit by becoming a two-family dwelling (duplex), which the Schedule of Uses permits by right only in R-3, R-4 and R-5 (and B-1), and by conditional use in B-2, B-3, B-4 and P-1. Duplexes are not allowed at all in the EST-1, R-1 and R-2 single-family districts, which cover most single-family neighborhoods. The duplex route also carries larger lot minimums: 10,000 sq ft and 60 ft width in R-3 (against 7,500 sq ft for a house), 8,000 sq ft in R-4 and 7,000 sq ft in R-5. This is a duplex conversion, not an accessory unit, so it is recorded as conditional under the directory's no-ADU-use convention.

Ordinance read October 2026

None (no ADU use). Duplex route: no per-unit cap; R-3 needs a 10,000 sq ft lot, 50% coverage and 35 ft height. Accessory buildings (which may not be dwellings): 1 story or 14 ft, at most 25% of a non-required yard and no larger than the house's ground floorNot required1.5 off-street spaces per dwelling unit (duplex route), so a second unit adds 1.5 spacesPermitted use
Independence

Section 4.05.J.2.f lets an ADU be attached to or detached from the primary dwelling, one per single-family or two-family lot of at least 5,000 sq ft. Which zones allow it was narrowed by Ordinance 2025-O-16 (second reading November 3, 2025), which revised the zones listing ADUs as permitted or conditional uses; as adopted it reportedly allows ADUs by right only in Residential Rural Estate (R-RE, 1-acre minimum lots), as a conditional use in Residential Large Lot Subdivision (R-LLS), and not at all in R-CVS, R-CPS and R-M. The online code has not absorbed that ordinance and still shows the 2020 table (permitted in R-RE, R-LLS and R-CVS, conditional in R-CPS and R-M), so the exact post-2025 zone split rests on the ordinance title plus contemporaneous reporting; the amended table (Attachment A) was not found posted.

Ordinance read October 2026

Attached ADUs (inside or added onto the house) follow the same zone split as detached ones: after Ordinance 2025-O-16 they are by right only in R-RE and need a Board of Adjustment conditional use permit in R-LLS, and are not allowed in the conventional, compact or mixed subdivision zones where most city lots sit. An attached ADU may have only one entrance on the front of the house (a second entrance goes on the side or rear) and must meet primary-structure setbacks. The zone split is read from the ordinance title and reporting because the amended use table was not found online.

Ordinance read October 2026

800 sq ft or 75% of the primary dwelling's living area, whichever is less; no taller than the primary structureRequired1 space per ADU

Where Table 4.1 marks the ADU "P" (R-RE after Ordinance 2025-O-16) it is a use by right needing only a zoning permit, subject to the Section 4.05 standards; where it is "C" (R-LLS) it needs a conditional use permit from the Board of Adjustment after a hearing under KRS 100.237, and the Board may attach conditions. The split between by-right and conditional zones holds under both the codified 2020 table and the 2025 amendment; only which zones fall where changed.

Ordinance read October 2026

Kenton CountyNot allowed

No attached or internal ADU use exists. The closest route is a two-family dwelling, a permitted use only in the R-1BB, R-1DD and R-1EE zones (on larger lots than a single-family home: three-quarter acre in R-1BB, 13,500 sq ft in R-1DD, 11,500 sq ft in R-1EE) and in the R-2 and R-3 multi-family zones. Two-family dwellings are not allowed in the A-1, A-2, R-RE, R-1A, R-1B, R-1C, R-1D, R-1E, R-1F or R-1G zones that cover most rural unincorporated land. R-1BB also allows quarters for live-in domestic help inside the house, which is staff housing, not a rentable unit.

Ordinance read October 2026

No ADU size cap (no ADU use). Two-family route: no per-unit cap; minimum lot 3/4 acre (R-1BB), 13,500 sq ft (R-1DD), 11,500 sq ft (R-1EE); 35 ft heightNot requiredNo ADU standard. Two-family route: 4 spaces total (2 per unit), versus 2 for a single-family homePermitted use
LexingtonAllowedAllowed800 sq ft (no cap for a basement conversion within the footprint); detached units also limited to 625 sq ft or 50% of the house, whichever is greater; detached height 20 ft at mid-gable and not above the houseNot requiredNonePermitted use
LouisvilleAllowedAllowed800 sq ft or 30% of the principal structure's gross floor area, whichever is greater; height no taller than the principal structureRequiredNo ADU-specific rule; Chapter 9 applies (no minimum in Traditional, Downtown and Urban Center Neighborhood form districts; Suburban form districts list 2 spaces per single-family or duplex unit)Permitted use
Murray

Murray's Zoning Code defines an accessory dwelling unit as an accessory structure (a guest house, pool house, mother-in-law suite or carriage house), so the use is a detached building by definition. In the R-1 and R-2 single-family districts it is a conditional use that needs a Board of Zoning Adjustments conditional use permit; in the Agricultural (AG) district it is permitted by right. No other district lists it. Accessory buildings must sit in the rear yard at least 5 feet from all lot lines.

Ordinance read October 2026

There is no attached or internal ADU use: the accessory dwelling unit is defined as an accessory structure, and accessory structures are by definition detached from the principal building. A second unit inside or attached to a house is therefore a two-unit (multi-family) dwelling, which is permitted by right in R-3, R-4 and R-5 and, per the use table, conditional in R-1 and R-2, although the R-1/R-2 district text itself lists no multi-family conditional use. A conversion must also meet the district's lot size, yard and parking rules for new construction.

Ordinance read October 2026

600 sq ft or 25% of the principal structure, whichever is largerNot requiredNo ADU-specific rule; 2 spaces per dwelling unit if the ADU is counted as one

In R-1 and R-2, where most single-family homes sit, an ADU requires a conditional use permit from the Board of Zoning Adjustments after a public hearing, with mailed notice to all adjoining owners at least 14 days ahead and a newspaper notice. The Board may approve, modify or deny the request and attach time limits or continuing conditions; the Zoning Official reviews open conditional use permits annually. The fee schedule lists $100 for a conditional use permit plus $5 recording. In the Agricultural district an accessory dwelling is permitted by right with a building permit.

Ordinance read October 2026

NicholasvilleNot allowed

No zone allows an accessory apartment inside a single-family home. The only route to a second unit in a house is a two-family dwelling (duplex), which is a by-right principal use only in the R-2 Two Family Residential district (8,000 sq ft minimum lot, or two lots of at least 3,429 sq ft split on a common wall). R-2 prohibits new single-family dwellings, so a lot must already be zoned R-2 or be rezoned through a Planning Commission hearing and City Commission ordinance. R-3 also keeps existing two-family dwellings. In the R-1 districts a resident family may take in up to two roomers or boarders, but that is not a separate dwelling unit.

Ordinance read October 2026

No ADU size cap (no ADU use); R-2 duplex: 35% lot coverage, 35 ft height; R-1 accessory buildings capped at 650 sq ft combinedNot required2 spaces per dwelling unitPermitted use
Oldham County

A detached accessory dwelling unit (a separate building, including a garage apartment joined to the house only by a breezeway) needs a conditional use permit from the Board of Adjustments after a public hearing. It is available in the AG-1, CO-1, R-1, R-1A, R-2 and R-2A districts (the AG-2 use table also lists it as a conditional use), not in R-3, R-4, R-4A, T or the commercial districts. The unit must meet the setbacks for a primary structure, stand at least 5 feet from the house, sit behind it, and counts as a whole dwelling unit toward the district's density limit. The county board granted such permits on 6-18-2026 and heard two more on 10-15-2026.

Ordinance read October 2026

AllowedDetached: 25% of the primary structure's square footage; attached: 30% of the primary structure's finished square footage; interior: no stated cap; no taller than the primary structureRequiredYes: off-street parking must be provided for the ADU (no space count specified)

Interior and attached units are by right with a building permit (staff review plus the owner-occupancy affidavit). Detached units require a conditional use permit from the Board of Adjustments after a public hearing with mailed and newspaper notice, and no certificate of land use issues until the board's minutes are approved at its next meeting. Applications in the unincorporated county and Crestwood go to the Oldham County Board of Adjustments; La Grange keeps its own Board of Adjustments for land inside its limits.

Ordinance read October 2026

Owensboro

Since Ordinance 16-2026 (second reading and adoption 8-18-2026), a detached accessory dwelling unit is a conditional use in the A-R, A-U, R-1A, R-1B, R-1C, R-1T and R-4DT zones, so every detached unit needs a conditional use permit from the Owensboro Metropolitan Board of Adjustment. It must sit in a side or rear yard, meet principal-structure setbacks and the Kentucky Building Code, and only one ADU is allowed per parcel. The multi-family zones (R-2MF, R-3MF) are not listed. Before the 2026 amendment the ordinance allowed accessory dwellings only above or behind business, office and industrial uses.

Ordinance read October 2026

Allowed50% of the principal structure's footprint (attached and detached); height per underlying zone (36 ft in R-1A to R-1T, no limit in A-R/A-U)Required1 additional off-street space

Attached ADUs are principally permitted in the agricultural and single-family zones, so they go through OMPC zoning review and a building permit with the attorney's covenant letter (and Health Department approval on septic). Detached ADUs are conditionally permitted and need a conditional use permit from the Owensboro Metropolitan Board of Adjustment after a public hearing, with septic approval required before the CUP application is filed. Under §8.2 'C' uses are 'permitted only with Board of Adjustment approval.'

Ordinance read October 2026

PaducahAllowed

Since Ord. 2022-10-8752 (10-25-2022) struck the words "if not contained within the footprint of the home," §126-98(2) reads "ADUs are permitted in the rear yard only," so the ADU section no longer carves out an internal unit; a rear addition sitting in the rear yard reads as permitted, while a basement or interior conversion inside the existing footprint is not clearly an ADU. A second unit inside the house can instead be built as a two-family dwelling, a principal permitted use in R-1, R-2 and R-3 (and R-4), but that route carries the two-family lot-area minimums (7,000 sq ft per unit in R-1, 6,000 sq ft per unit in R-2). Ask the Planning Division how it classifies an internal unit before designing one.

Ordinance read October 2026

50% of the rear yard behind the principal dwelling, capped at the principal dwelling's ground floor area; height no taller than the principal dwellingRequired1 additional spacePermitted use
RichmondNot allowed

There is no ADU use, so an internal or attached second unit is possible only by making the house a two-family (duplex) dwelling. Duplex dwellings are permitted by right in R-2 (Two Family Residential), R-3 (Multi-Family) and PUD zones, and are not allowed in the R-1A, R-1B, R-1C, RE, MP or AG zones that cover most single-family neighborhoods. The duplex must meet the district's lot standards (8,500 sq ft minimum site in R-2; 6,500 sq ft for the first unit plus 2,800 sq ft per additional unit in R-3). Basement and loft apartments are listed only in the B-2 Central Business District (conditional use) and B-3 (loft apartments for business personnel only).

Ordinance read October 2026

No ADU size rule (no ADU use); a duplex follows the district's dimensional standards (35 ft height in R-1 and R-2, 65 ft in R-3)Not requiredDuplex: 2 spaces per unit (up to 3 bedrooms), 3 per unit for 4 to 5 bedroomsPermitted use

Summarized from each city's ordinance text, most recently read October 2026. Tap a value marked with an info icon to see exactly what it depends on, straight from the ordinance. Nearly every value has zone, lot-size, or process caveats beyond that; the per-city pages carry the full notes and code citations. Treat this as orientation, not a permit determination.

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Reading the table

  • Detached ADU is the make-or-break column for backyard cottages: minimum lot sizes (often 8,000 to 14,500 sq ft) hide behind many of the "Allowed" values, so check your lot before celebrating.
  • Attached / internal (basement apartments, additions) is legal almost everywhere and is usually the path of least resistance.
  • Approval: "Permitted use" means staff-level sign-off; "Conditional use" means a public hearing, which adds time, cost, and uncertainty.

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