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), so 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
Louisville ADU permit questions
- Do I need a permit to build an ADU in Louisville?
- Yes. An accessory dwelling unit (ADU) in Louisville requires a building permit. ArchPermit tracks 15 cited requirements for this jurisdiction (11 required, the rest conditional). Always confirm the exact forms, fees, and code edition with the local permitting authority that issues the permit.
- What does an ADU permit package require in Louisville?
- Core required items include: ADU Application (Office of Planning); Building Permit Application (Construction Review); Construction Plans; Energy Compliance (KY prescriptive package or REScheck); Exterior Building Elevations; Floor Plans, plus 5 more. Each requirement links to its authoritative source, and nothing is permit-ready until an independent licensed professional reviews and seals it.
- How are ADU permits submitted in Louisville?
- Louisville accepts permit submittals via Construction Review Online Permitting Portal. ArchPermit prepares a draft package you can submit there after a licensed architect reviews and seals it.