ADU Rules in Knoxville, TN (2026)
ADU rules, permit requirements, size limits, and fees for Knoxville, TN. Source-cited from official municipal code.
Yes, ADUs are allowed in Knoxville, TN.
Knoxville, TN permits accessory dwelling units (ADUs) on residential properties. ADUs — also called granny flats, in-law units, backyard cottages, or secondary suites — are secondary housing units on a single-family or multifamily lot. State and local law governs the approval process. In Knoxville, the Knoxville Plans Review and Building Inspections handles ADU permit applications. Below you will find the current size limits, setbacks, fees, and timeline for building an ADU in Knoxville.
ADU Size Limits
ADU Size Limits in Knoxville: Detached ADU: up to 750 sq ft (max height: 20 feet). Attached ADU: 35% of primary dwelling floor area. Knoxville Zoning Ordinance accessory dwelling unit provisions. Detached ADUs limited to 750 sqft in RN residential zones. JADU is a California-specific concept not applicable in Tennessee.
| Type | Max Size | Max Height |
|---|---|---|
| Detached ADU | 750 sq ft | 20 feet |
| Attached ADU | 35% of primary dwelling floor area | Per zone height limit |
Permit Fees
ADU Permit Fees in Knoxville: Plan check fee: $100–$600. Building permit fee: Based on construction value — typically $500–$2,000. Impact fees: Knoxville charges KUB connection fees; development impact fees are modest. School fees: None or N/A. Total estimated permit cost: $1,200–$5,000 total fees. Knoxville permit fees are moderate. KUB (Knoxville Utilities Board) connection fees apply for new utility connections.
| Fee Type | Amount |
|---|---|
| Plan Check | $100–$600 |
| Building Permit | Based on construction value — typically $500–$2,000 |
| Impact Fees | Knoxville charges KUB connection fees; development impact fees are modest |
| School Fees | None |
| Total Estimate | $1,200–$5,000 total fees |
Permit Timeline
Knoxville ADU Permit Timeline: Knoxville Plans Review and Building Inspections permit: typically 4-6 weeks for residential permits. Construction typically 4-12 months. Apply through the Knoxville Plans Review and Building Inspections online permit portal. Phone: (865) 215-3800.
Setback Requirements
ADU Setback Requirements in Knoxville: Front setback: follows zone standard. Side setback: 5 feet. Rear setback: 5 feet. Knoxville Zoning Ordinance ADU setbacks. Minimum 5 ft rear and side setbacks for detached ADUs in RN zones.
Parking Requirements
Parking Requirements: 1 parking space required per ADU. Knoxville has limited public transit — KAT (Knoxville Area Transit) operates buses. Areas near UT campus may have alternative parking arrangements.
Restrictions & Requirements
- ADU must be on same lot as primary single-family dwelling
- Lot must meet minimum size requirements for the RN zone
- ADU cannot be separately conveyed from primary lot
- Total lot coverage must comply with zone standards
- Knoxville STR registration required if ADU is short-term rented
- Must comply with Tennessee Residential Code
How Many ADUs Are Allowed?
Number of ADUs Allowed in Knoxville: Single-family lots: 1 ADU per single-family lot in qualifying RN zones. Multifamily properties: Additional units may be allowed in RN-4 through RN-6 zones. Knoxville allows one accessory dwelling unit per single-family residential lot. UT's large student population creates strong rental demand in neighborhoods like Fort Sanders, 4th and Gill, and the Old North Knox corridor.
Single-Family Lots
1 ADU per single-family lot in qualifying RN zones
Multifamily Properties
Additional units may be allowed in RN-4 through RN-6 zones
Historic District Considerations
Historic District Requirements: Knoxville has 12 historic districts where additional design review may be required for ADU construction. Design review approval is required before obtaining a building permit for properties in historic overlay zones. Knoxville has significant historic resources: Fort Sanders (Victorian neighborhood, National Register), Old North Knoxville, 4th and Gill, and the downtown Market Square area. The 1982 World's Fair site (Sunsphere still stands) is a distinctive landmark. Knoxville Historic Zoning Commission oversees design review for exterior changes to properties in H-1 (Historic Overlay) zones. The Metropolitan Planning Commission can provide specific guidance on historic designations. Look up historic district boundaries at: https://www.knoxvilletn.gov/government/city_departments_offices/plans_review_and_building_inspections/historic_zoning
Frequently Asked Questions
Can I build an ADU in Knoxville?
Yes. Knoxville, TN allows accessory dwelling units. On a single-family lot you can build 1 ADU per single-family lot in qualifying RN zones.
How big can an ADU be in Knoxville?
The maximum size for a detached ADU in Knoxville is 750 square feet.
How long does it take to get an ADU permit in Knoxville?
The typical ADU permit timeline in Knoxville is Knoxville Plans Review and Building Inspections permit: typically 4-6 weeks for residential permits. Construction typically 4-12 months.. Total estimated permit fees are $1,200–$5,000 total fees.
Do I need extra parking for an ADU in Knoxville?
No, Knoxville does not require additional parking for ADUs.
Do I have to live on-site to have an ADU in Knoxville?
No, owner-occupancy is not required for ADUs in Knoxville.
Source: Knoxville Zoning Ordinance — Accessory Dwelling Unit provisions. Last verified April 6, 2026. View source