Accessory Dwelling Unit (ADU) Regulations in Louisville

Max Size- 

• Detached: 800 sq/ft (Does not include garage space)
• Attached: <50% of primary residence or 1,000 sq/ft, whichever is less

Max Height- 

• Detached: 20’ unless in Old Town then 25’
• Attached: Same as primary residence building height maximum

Under HB 24-1152, Louisville must allow ADUs in all single-family zoning districts. This means:
✔ ADUs are now allowed on any lot where a single-family home is permitted.
✔ HOAs cannot prohibit ADUs, although homeowners should check their HOA’s design requirements.
✔ No public hearings or discretionary approvals are required—ADUs must be approved through an administrative process with objective zoning standards.

Louisville has specific size limitations and design standards to ensure ADUs fit within neighborhoods.

Maximum ADU Size

• Detached ADUs: Up to 800 sq/ft (garage space is not included in this calculation).
• Attached ADUs: Limited to 50% of the main home’s floor area or 1,000 sq/ft, whichever is smaller.

Height Limits

• Detached ADUs:
  
  • 20 feet in most zoning districts.
  • 25 feet in Old Town overlay districts to accommodate roof pitch requirements and alley access.
• Attached ADUs: Must follow the same height limits as the primary home.

Setbacks & Placement

• Detached ADUs must follow accessory building setbacks.
• Attached ADUs must follow primary residence setbacks.
• Front Setbacks: Detached ADUs must match setback requirements for other accessory buildings in the district.
• Side & Rear Setbacks: Must be no greater than what is required for primary residences.

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HB 24-1152 requires cities to allow ADUs without designated parking, except in these cases:
✔ If no parking is currently required for the primary home, parking cannot be required for the ADU.
✔ If the lot does not have an existing parking space for the primary home, no additional parking is required.

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• ADUs must share water and sewer connections with the primary home; separate utility meters are not required.
• If a detached ADU requires a larger water tap size, the homeowner must pay the incremental System Development Fees.

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• HB 24-1152 prohibits cities from requiring owner occupancy meaning ADUs can be rented out separately from the primary home.
• ADUs cannot be sold separately from the main home—they must remain part of the same lot.
• Short-term rentals (STRs) are still prohibited, except in Planned Unit Developments (PUDs) where STRs were previously allowed.

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Under HB 24-1152, all ADU approvals must be handled administratively—meaning there are:
✔ No public hearings
✔ No subjective design reviews
✔ No neighborhood approval required

The ADU approval process in Louisville includes:

1. Zoning & Site Plan Review – Ensure the lot meets ADU requirements.
2. Building Permit Application – Submit architectural plans, site plans, and required documents.
3. Plan Review & Approval – The city will verify compliance with zoning and building codes.
4. Construction & Inspections – Once approved, the ADU must be built according to the approved plans and pass final inspections.

Additionally, Louisville is offering a one-year grace period for existing unpermitted ADUs to become legally compliant through a simplified registration process.

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Incentives for Affordable Housing & Historic ADUs

Louisville has additional incentives for ADUs that are either:
✔ Deed-restricted for affordable housing
✔ Part of a historic preservation project

ADUs that qualify may receive:
✔ Increased maximum ADU size
✔ Additional flexibility in development standards
✔ Potential state funding opportunities

Navigating Louisville’s ADU regulations can be complex, but Kindred Tiny Homes makes the process easy by handling every step from zoning approvals to final construction.

• We specialize in Louisville’s ADU regulations ensuring compliance with all zoning and permitting requirements.
• We provide full-service ADU development from design and engineering to construction and project management.
• We maximize your investment creating a high-quality ADU that enhances property value and meets your needs.

If you’re considering building an ADU in Louisville, contact us today for a free consultation, we’ll guide you through your options and help bring your vision to life!

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