Louisville ADU permit requirements
Last reviewed: June 22, 2026
Quick answer
Permitting an accessory dwelling unit (ADU) in Louisville, Kentucky means pulling a building permit from the local authority that issues it. ArchPermit tracks 15 source-cited requirements (11 required, the rest conditional) for this jurisdiction. Submittals go through Construction Review Online Permitting Portal. These requirements were last reviewed June 22, 2026; confirm the exact forms and fees with the local permitting authority.
A source-cited checklist of what an ADU (accessory dwelling unit) permit package needs in Louisville. Every item links to its authoritative source; items that vary are flagged to confirm locally.
An ADU goes through two Louisville Metro tracks: an Office of Planning ADU application (zoning/use review, $50) and a Construction Review building permit. The 2021 Land Development Code reform replaced the accessory-apartment conditional-use permit with a 'permitted use with standards' (LDC 4.3.25) — ADUs may be permitted in all zoning districts that permit residential use. Owner-occupancy is required (the owner must reside in the principal dwelling or the ADU). One ADU per lot; max 800 sf or 30% of the principal structure's gross floor area, whichever is greater. New habitable ADU floor area is not allowed on lots with environmental constraints. (Confirm the current codified LDC section number — the reform report says 4.3.25; the codified location may now read 4.2.3.)
- ADU Application (Office of Planning)required
The Office of Planning ADU application form ($50 fee); captures zoning/form district, attached/detached, owner-occupancy, STR, parking, and environmental constraints.
source · reviewed 2026-06-22 - Building Permit Application (Construction Review)required
The Construction Review building-permit application — project type 'New Structure,' units/bedrooms/height/SF, infill-lot and prior-approval flags.
source · reviewed 2026-06-22 - Construction Plansrequired
Minimum 2 sets, drawn to scale, min sheet 8½×11 — a required building-permit attachment.
source · reviewed 2026-06-22 - Energy Compliance (KY prescriptive package or REScheck)required
Building-envelope energy-efficiency compliance via the KY prescriptive method package or a REScheck report.
source · reviewed 2026-06-22 - Exterior Building Elevationsrequired
All sides of the structure, building height from finished grade, exterior finishes, and egress doors/windows.
source · reviewed 2026-06-22 - Floor Plansrequired
Each affected floor: interior/exterior walls, door/window locations, dimensions, room labels, and smoke-detector locations.
source · reviewed 2026-06-22 - Foundation & Framing Detailsrequired
Footing size/depth + reinforcing; foundation wall thickness/rebar; wall/floor/roof framing and stair details.
source · reviewed 2026-06-22 - Letter of Explanationrequired
A detailed letter outlining the plans/proposal (ADU application checklist).
source · reviewed 2026-06-22 - Owner Signaturerequired
Owner signature is required on the ADU application and the deed-restriction acknowledgement.
source · reviewed 2026-06-22 - Site Plan (fully dimensioned, to scale)required
Site plan showing ADU placement and distances from structures to property lines, submitted with the Planning ADU application.
source · reviewed 2026-06-22 - Site Plan (with setbacks)required
Required attachment on the building permit application — size/location of new + existing structures and distances from lot lines.
source · reviewed 2026-06-22 - MSD ESPC Form (erosion / soil disturbance)conditional
Required for any soil disturbance — a required building-permit attachment.
source · reviewed 2026-06-22 - MSD Flood Permit / MSD Approvalconditional
Required if in a flood zone; MSD approval is also required for any accessory structure over 900 sf regardless of flood zone.
source · reviewed 2026-06-22 - Property-Owner Proof (recorded deed)conditional
If applying as the homeowner and the system doesn't show you as owner of record, provide a copy of the recorded deed (plus the required owner affidavit).
source · reviewed 2026-06-22 - Sealed/Stamped Plans (KY architect/engineer)conditional
Required for retaining walls ≥4 ft, log cabins, pole-barn construction, trusses/pre-engineered items, or special conditions.
source · reviewed 2026-06-22