Everything You Need to Know Before You Build
As more families look for creative ways to house aging parents, adult children, or even domestic employees, Accessory Dwellings (ADUs) are becoming a popular option across Tennesseeāincluding right here in Hendersonville.
Whether youāre planning an in-law suite, a garage apartment, or a backyard cottage, here's a guide to help you navigate Hendersonvilleās ADU regulations.
ā What is an ADU?
An Accessory Dwelling Unit (ADU) is a second living space on a lot that already has a single-family home. ADUs can be:
- āAttached (like a basement apartment or converted bonus room)
- āDetached (a small structure behind the main house)
Each unit must include its own kitchen, bathroom, and sleeping space.
š General Accessory Dwelling Requirements in Hendersonville
Before starting your project, here are the key rules:
- āOwner must live on the property full-time (at least 75% of the year)
- āOnly family members or employees can live in the ADU (parents, grandparents, adult children, in-laws, domestic workers, etc.)
- āOne driveway must serve both the main house and the ADU
- āAt least 4 off-street parking spaces are required (garages donāt count)
- āShared utilities and mailbox ā no separate meters or addresses
- āA legal covenant must be recorded with the county
- āOnly one accessory unit per lot ā either attached or detached, not both
š§± Attached ADUs
If youāre planning to build a unit inside or attached to your home, the rules are:
- āCanāt exceed 40% of the total heated square footage
- āMust be accessed from inside the main house
- āNo visible second front doors from the street
- āNot allowed if restricted by neighborhood covenants
- āNo variances allowed from these conditions
š” Detached ADUs
Detached dwellings offer more independence but come with stricter guidelines:
- āMinimum lot size: 30,000 sq ft
- āMust be placed behind the main house and at least 20 ft from property lines
- āMust visually match the style, color, and materials of the main home
- āRequires a Conditional Use Permit from the Board of Zoning Appeals ($250 application fee)
- āNot allowed if restricted by HOA or subdivision rules
š Size + Setback Guidelines
Use this table to check what you can build based on your lot size:
| Lot Size | Max Size of ADU | Detached ADU Allowed? |
| Under 15,000 sq ft | 800 sq ft or 50% of main home | ā Not Allowed |
| 15,001ā30,000 sq ft | 1,200 sq ft or 50% | ā Not Allowed |
| 30,001ā43,559 sq ft | 1,500 sq ft or 50% | ā With Permit |
| 1ā3 acres | 1,800 sq ft or 50% | ā With Permit |
| 3+ acres | 2,500 sq ft or 50% | ā With Permit |
Additional limits:
- āMax height: Same as your main home or 35 ft (whichever is less)
- āMust not sit on any easement
- āOnly 2 accessory buildings total allowed (not counting pergolas/gazebos under 120 sq ft)
š§ Need Help Navigating the Process?
Adding an ADU in Hendersonville can be a great way to maximize your propertyābut getting it right means following all local regulations.
At Fabl Design, we help homeowners design ADUs that meet city standards while beautifully complementing your existing home.
š Ready to explore your options?
Contact us today to talk through your property, goals, and timeline. Letās see if an ADU is right for you.
Disclosure
The information provided in this blog post is intended for general informational purposes only. While every effort has been made to ensure the accuracy and completeness of the content, zoning regulations are subject to change, and their interpretation may vary. Therefore, this post may not capture all nuances or recent updates.
Readers are advised to consult the local municipality's official zoning documentation or contact local zoning authorities for the most current and detailed information specific to their property or project. The author assumes no responsibility for any errors or omissions or for actions taken based on the information provided herein.