Accessory Dwelling Units (ADU)

Accessory Dwelling Units Pre-approved Building Plans - AARP Community Challenge Grant (2023)

Planning and Design Services was awarded an AARP Community Challenge Grant to host a design competition and purchase ADU plans for the public to use free-of-charge when applying for a building permit. A minimum of 3 sets of ADU plans are intended to be purchased and hosted online. Participants may submit architectural and construction drawings for one or each of the following projects:

  • A detached single-story ADU for a Traditional Neighborhood 
  • A detached 2-story "carriage-house" style for a Traditional Neighborhood
  • A detached single-story "backyard cottage" for a Suburban Neighborhood

Three plans have been selected and are currently under review by Louisville Metro Government. Once finalized, they will be made available for the public to use free-of-charge. Please check back in January 2024.

Challenge Grant Resources
  • July
    • Open House July 21, 2023
    • Submittal window opens July 24, 2023
  • August
    • Accepting submittals
  • September
    • Deadline for submittals September 7, 2023
    • Post submittals online for 2-weeks starting the week of September 11th
  • October
    • Selection Committee meets 1st week of October to grade submittals
    • Winners will be announced and notified by October 13, 2023
    • Post-selection building and zoning review to be conducted beginning October 16, 2023
    • Revisions to address comments made during review will be due within 2 weeks
  • November
    • Plans due by November 21, 2023
    • Post-project outreach conducted by staff
  • December
    • After-action report due to AARP
Submittal & Evaluation Criteria

Submittals shall demonstrate conformance with applicable zoning, building, and agency (MSD, LWC, LG&E, etc.) regulations that generally apply to the construction of an accessory structure with a dwelling unit in Louisville-Jefferson County, KY. Selected plans will receive a zoning and construction review, and participants will be expected to revise the plans accordingly. Purchased plans will require minimal revision, if any, to adjust to the specific needs of future subject sites, including topographic and geologic conditions, when a permit is being requested. 

Submittal Criteria

  • Preliminary Floor Plan
  • Preliminary Construction Plan
  • Preliminary Rendering

Evaluation Criteria (100 pts)

  • Universal Design (20 pts)
  • Exterior Design and Compatibility between multiple neighborhoods (20 pts)
  • Plan Options, including but not limited to layout and number of bedrooms, roof styles, foundation, and ease of construction (20 pts)
  • Sustainability & Energy Efficiency (15 pts)
  • Estimated Construction Cost, including professional services required (10 pts)
    • Plans will be graded based on the range of estimated costs of all submittals within each category.
  • Readiness for Permitting (10 pts)
  • Cost of plans, not to exceed $7,500 (5 pts)
    • Plans will be graded based on the range of estimated costs of all submittals within each category


Do pre-approved plans save time? Yes

  • Planning review – setback and private yard is the only check
  • Building review – 85% complete

Do pre-approved plans save money? Yes

  • A standard plan set ranges in cost from $1,500 - $5,000. This includes scaled drawings for one construction method or type. Fully customizable and original plan sets can reach as high as $10,000.
  • Pre-approved plan has already been purchased

Is the pre-approved plan permitted? No

  • Pre-approved is not pre-permitted – every site is unique
  • A building permit is required but the plan provided is a near complete plan to be used for permitting. Consultation with the original designer may be necessary for changes.
  • A site plan remains required
  • Geologic review may still be required

Who is hosting the pre-approved plan? Plans will be hosted by Louisville Metro.

  • Consultation with the original designer may be necessary for changes or additional review, including:
    • Topography
    • Geology
    • Any other modification desired by the applicant
  • Louisville Metro will not be liable for failed construction in the field using a pre-approved plan
Pre-Approved Plan Examples (National)

City of Eugene, Oregon - Pre-approved ADU Plans Program

City of Seattle, Washington - Pre-approved DADUs (ADUniverse)

San Diego County, California - County Standard ADU Building Plans

City of Los Angeles, California – Pre-approved Standard Plans

City of Del Mar, California – ADU Sample Floor Plans

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

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

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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