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 local building department 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: 18 feet). Attached ADU: 40% 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 · Verified June 7, 2026 · Source | 18 feet · Verified June 7, 2026 · Source |
| Attached ADU | 40% of primary dwelling floor area · Verified June 7, 2026 · Source | See official source |
Permit Fees
ADU Permit Fees in Knoxville: Plan check fee: Varies. Building permit fee: Varies. Impact fees: None. School fees: None or N/A. Total estimated permit cost: Varies.
| 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 | See official source |
Permit Timeline
Knoxville ADU Permit Timeline: Permit timeline has not been confirmed — contact the department for current processing times. Apply through the local building department online permit portal. Contact them through their official website for current contact information.
Setback Requirements
ADU Setback Requirements in Knoxville: Front setback: follows zone standard. Side setback: 5 feet. Rear setback: 5 feet.
Parking Requirements
Parking Requirements: 1 off-street parking space required for ADU
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: Only one ADU is permitted per lot.. Multifamily properties: not confirmed — see official source.
- Single-Family Lots
- Only one ADU is permitted per lot. · Verified July 14, 2026 · Source
- Multifamily Properties
- Additional units may be allowed in RN-4 through RN-6 zones
Statewide Preemption
ADU Preemption
We could not confirm a statewide ADU preemption statute for Tennessee.
View Tennessee preemption detailsFrequently Asked Questions
Can I build an ADU in Knoxville?
Yes. Knoxville, TN allows accessory dwelling units. On a single-family lot you can build Only one ADU is permitted per lot..
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?
Knoxville parking rules for ADUs: 1 off-street parking space required for ADU
Do I have to live on-site to have an ADU in Knoxville?
Owner-occupancy requirement in Knoxville: One of the dwelling units must be occupied by the owner of the property
Source: Knoxville Zoning Ordinance — Accessory Dwelling Unit provisions. Last verified April 6, 2026. View source