Accessory Dwelling Units (ADU)

What is an ADU?

An ADU or Accessory Dwelling Unit is a smaller, secondary residential unit located on the same lot as the main residence. ADUs may be called by many names, including granny flats, carriage houses, basement apartments, or mother-in-law suites. ADUs provide complete, independent living facilities (which at a minimum includes permanent provisions for living, sleeping, cooking and sanitation which are accessed independently). Two types of ADUs are allowed; they can be attached to the main residence or detached as a separate structure.

Types of ADUS


Pre-Approved ADU Building Plans - NOW AVAILABLE!

The Office of Planning was awarded an AARP Community Challenge Grant in 2023 to host a design competition with the intent of purchasing and hosting ADU plans for the public to use free-of-charge in their building permit application. Three (3) sets of plans from local designers have now been selected. These plans are “pre-approved,” which indicates that the Offices of Planning and Construction Review have reviewed each plan and determined that they comply generally with local zoning and building code requirements. Each site is unique and additional information may be needed for each to finalize a permit application.


Available ADU Plans

Studio MAYO Architecture + Construction
  • This fully customizable ADU begins with a base model floor plan of 450 sq. ft. (15'x30') that can be configured to accommodate 2 full bedrooms and a covered porch.
  • The plan set includes a variation of roof types, window details, roof overhangs, and porches
  • Studio MAYO has prepared this plan set with the user in mind by including step by step instructions and providing forms within the plan set to customize your permit.
  • If the plan with all its options still isn't what you're looking for, Studio MAYO is available to customize this plan further or work with you on your unique needs. Please contact Studio MAYO at (502)759-5197 or visit them online at 

Download Plan here:


Studio Co+Hab
  • This 2-story, carriage house style ADU is fully customizable, including a single-story option without the garage below
  • The ADU is available as a studio or 1-bedroom unit
  • Both gable and shed roof options are available for each configuration
  • Once on the 2nd story, the living space is universally designed (required by design contest) 
  • If the plan with all its options still isn't what you're looking for, Studio Co+Hab is available to customize this plan further or work with you on your unique needs. Please contact Studio Co+Hab at (502)287-9003 or visit them online at 


Download Plan here:

Studio Co+Hab ADU

TInsley ADU image
Dana Tinsley - Imagine This

These plans are pending final review and will be made available as soon as possible

  • This single-story, 1-bedroom , 760 sq. ft. cottage offers zero-entry and universal design throughout
  • The exterior could be finished with multiple materials that match your home or the neighborhood
  • The simplicity of the plan set helps keep it accessible to all skills levels of building and construction 


Download plan here:

-Coming Soon-

Louisville Metro is the owner of each plan available above. The use of these plans is at the sole-discretion of the user and all risk is assumed.

Using and Submitting Pre-Approved Plans
Select Plan, Consult with a Professional, and Finance
  • Review the plans in the list above and make a selection
  • Once a plan is selected, reach out to a professional contractor or builder to determine placement on your lot
    • Be sure to discuss slope, soils, floodplain, access, setbacks or any other environmental feature that may effect your project 
    • Get a quote for the job (it's always a good idea to get a 2nd opinion)
  • Secure financing - Building an ADU is not free! 
    • Do you qualify for funding through the Louisville Affordable Housing Trust Fund? Learn more HERE.
Site Plan Required

A site plan is required for the building permit application and must accurately represent the placement of the ADU on the lot. The plan must be fully dimensioned with distances from structures to property lines. It must be drawn to-scale to confirm the accuracy of the dimensions shown. A professional survey is not required, but may be needed where the ADU is proposed near a property line or where there is doubt about the exact location of a property boundary (fences are not legal boundaries).

Site Plan Resources:

Submit Building Permit Application 

Permitting Basics for Pre-Approved Plan: 

  • The application name must include "Pre-approved ADU" 
  • The description provided in the permit application must include the model name of the ADU (ex: Mayo ADU) and list the options selected with the plan (The plan submitted should also note, where appropriate, the options selected)
  • The owner of the property must reside in either the main home or ADU (LDC 4.3.27). If the owner does not live on the property, a permit may not be issued through this process. The Office of Planning is an agency reviewer on all new residential building permits. The permit description must indicate ownership.

Submitting the Building Permit:

Additional Information on the Permitting Process:

  • Additional reviews may be required, including MSD, Health, LWC, LG&E, etc. These agencies may require additional fees for review. Utilities are NOT pre-approved.
  • Historic Preservation staff has reviewed each plan for consistency with districts. However, the controlling ordinance does not allow for staff approval on freestanding structures in preservation districts. A certificate of appropriateness will require review and approval. For more on preservations district, please their page by clicking HERE.
  • If you are in a floodplain, please consult Louisville MSD prior to submitting a building permit
  • Should an ADU from the list of pre-approved plans encroach upon a required setback as listed in the Land Development Code, a variance may be required. The fee will be waived and the application will be expedited. Typical accessory structure setbacks are 5' from rear property lines and 2' from side property lines. Non-public hearing variances are also available with the consent of your neighbors.

What are the Rules for ADUs?

Summary of ADU Regulations

One ADU per single-family lot

  • The standards listed below apply to the development of an ADU on a single-family lot in a single-family zoning district. Multi-family zoning districts are permitted to have 2-units as the base density and are not required to comply with these special standards. 

Size: 800 sq. ft. or 30% of the size of the principal structure (whichever is greater)


  • Attached - All yard and setback requirements of the principal structure shall be met and it shall be located either to the side or behind the principal structure
  • Detached - All yard and setback requirements for an accessory structure (e.g., freestanding garage) shall be met and it shall be located either to the side or behind the principal structure


  • Attached - An exterior staircase used to access a second story or higher ADU shall not be located on the front façade of the structure
  • Detached - The exterior pedestrian entrance to the ADU shall be located facing the principal structure or side yard

Maximum Height:

  • Attached - Height shall not exceed the height of the principal structure
  • Detached - Height shall not exceed the maximum height permitted for an accessory structure or the height of the principal structure

No short term rentals (e.g., Air B&B) without a conditional use permit

Property Maintenance: Any property maintenance violations within the last 12 months must be resolved

Parking: Off-street parking shall meet the requirements of the Land Development Code

Environmental Constraints: New construction shall not be allowed on areas that contain environmental constraints

Owner Occupancy: The owner of the property shall reside on the property

These provisions do not override any deed restriction or homeowners’ association declarations restricting ADUs

To view the full text of the adopted standards for Accessory Dwelling Units please visit the Land Development Code and view Section 4.3.27 available here:*

Land Development Code

*Not all cities with zoning authority have adopted these standards. Please consult the correct version of the code for your city or call us at (502)574-6230 with any questions.

Process to apply for an ADU

ADU Process Image


Step by Step Process Guide       ADU application

This process does not apply to pre-approved ADU building plans

Events Showcasing ADU's

  • Louisville & Lexington ADU Conference: On February 1 & 2, 2022, Louisville and Lexington collaborated with AARP and AARP-Kentucky to host a conference offering national expertise in areas critical to the success of ADUs as an emerging housing type, including sessions on design and construction, appraisal, lending, and real estate. To watch these sessions and learn more about the role of each industry, please check out the conference site by clicking the button below:

Louisville & Lexington ADU Conference

Louisville & Lexington ADU Conference List of Resources

  • White House Event on Making it Easier to Build Accessory Dwelling Units (ADUs):  On February 1, 2022, the White House hosted a virtual event on making it easier to build ADUs. Featured speakers included Ambassador Susan Rice, White House Domestic Policy Advisor; Sandra Thompson, Acting Director, Federal Housing Finance Agency; Lopa Kolluri, Principal Deputy Assistant Secretary, Office of Housing and the Federal Housing Administration, Department of Housing and Urban Development; Mike Hernandez, Vice President Engagement & Impact, Fannie Mae; and other housing experts and leaders. Watch the video below:


General Resources
Ordinance and Staff Report
Research and Data
ADU Application Look-up

AARP Community Challenge Grant (2022)

Neighborhood View of Accessory Dwellings
ADU_Neighborhood View
ADU Neighborhood View

In coordination with the Office of Council District 21, the content curated on this page was made possible through the receipt of an AARP Community Challenge Grant. The grant's stated purpose was to "create community awareness of Louisville’s goals outlined within Comprehensive Plan 2040 by addressing equity issues related to affordable housing through ADUs, supporting older adults and minority communities." The project focused on 5 primary needs:

  1. Marketing strategy to spread community awareness
  2. Recording community experiences
  3. Digital outreach, including videos
  4. Baseline survey of community understanding
  5. Recommendations to Planning and Design Services for a community education model to be utilized for future LDC Reform efforts

MKSK was selected as the consultant to meet these project goals. A final report, video, and resources were completed on May 31, 2022. 

Final Report - Memo



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