ADU rules in 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).

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.

§4.05.J.2.i caps the ADU at 75 percent of the primary dwelling's living area or 800 square feet, whichever is less, and §4.05.J.2.j bars it from exceeding the height of the primary structure. The lot must be at least 5,000 square feet. A detached ADU also counts toward the cumulative accessory building floor area, which in R-CVS, R-CPS and R-M may not exceed 10 percent of the rear yard or the floor area of the primary structure. Exceeding the height cap takes a variance (the Board of Adjustment heard one for a 780 square foot garage with an ADU at 412 Hallam Avenue in 2024).

§4.05.J.2.k requires that the property owner occupy either the primary dwelling unit or the accessory dwelling unit. The text is a continuing standard of the use, not only an application-time test. Kentucky has no state law preempting owner-occupancy rules.

Table 10.1 requires 1 off-street parking space per accessory dwelling unit, in addition to the primary home's own requirement (for a single-family detached home, 2 spaces beyond any garage spaces where on-street parking is provided, or 4 where it is not). Separately, §7.04.C.7 requires at least one attached or detached garage for each dwelling unit receiving a zoning permit for initial construction in R-LLS, R-CVS, R-CPS, R-M and MU; the ordinance does not say whether that reaches an ADU, so confirm with PDS.

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.

Because the owner must occupy one of the two units, the other can be rented long-term. §4.05.J.2.l lets an ADU serve as a short-term rental where short-term rentals are permitted, and §4.05.F.2.e allows short-term rentals in the primary structure and one ADU, with a maximum stay of 29 days and a one-night minimum. Owner-occupied short-term rentals are conditional uses in R-LLS, R-CVS, R-CPS, R-M and R-MF and permitted in MU; non-owner-occupied ones are conditional only in R-M and R-MF. Long-term landlords fall under Code of Ordinances Chapter 112 (business regulatory license and rental registry), but §112.04 exempts a single rental unit in an owner-occupied residence that is the owner's principal residence.