Knox County, TN Building Setbacks & Zoning: Lot Coverage Limits (2026)
Key Facts
- Max lot coverage (RA zone)
- 30% of lot area, main + accessory
- Governing section
- Zoning Ordinance Sec. 5.11.10
- Minimum lot size (sewered)
- 10,000 sq ft
- Minimum lot size (unsewered)
- 20,000 sq ft
- Civil penalty
- $10-$500 per day, per violation
- Appeal body
- Board of Zoning Appeals, 30 days
- Enforcing agency
- Dept. of Code Administration and Enforcement
Summary
Knox County's RA Low Density Residential Zone caps lot coverage at 30 percent: main and accessory buildings combined cannot cover more than three-tenths of any lot. The rule applies within RA zoning under Zoning Ordinance Sec. 5.11.10, alongside the zone's separate front, side and rear yard setbacks, and is enforced by the Department of Code Administration and Enforcement.
5.11.10. Maximum lot coverage. Main and accessory buildings shall cover not more than thirty (30) percent of the lot area.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 23).
Full Breakdown
Knox County's RA Low Density Residential Zone is intended to protect low-density residential areas from encroaching uses, and its area regulations cap building coverage at 30 percent of the lot under Zoning Ordinance Sec. " That single sentence is the whole rule: there is no separate impervious-surface or paving standard in the RA zone, so driveways and patios are not counted, only roofed structures. The cap works alongside the zone's other area regulations under Sec. 09: lots served by a sanitary sewer need at least 10,000 square feet, while unsewered lots need 20,000 square feet, and the county health department can require even more where percolation is poor.
Height is capped separately at three stories or 35 feet for main buildings and 18 feet for accessory buildings under Sec. 11. Every zone sets its own coverage number: the RAE Exclusive Residential and A Agricultural zones also cap at 30 percent (Secs. F), the RP Rural Preservation Zone drops to 10 percent (Sec. F), and commercial districts such as PC Planned Commercial and EC Employment Center allow up to 50 percent (Secs. D). Before adding a garage, sunroom or detached shop, a property owner needs a building permit from the Department of Code Administration and Enforcement under Sec.
01; the permit fee doubles under Sec. 03 if work starts before the permit issues, and plan review is where staff check the addition against the 30 percent ceiling.
Violations & Fines
Knox County's Department of Code Administration and Enforcement can assess a civil penalty of not less than $10.00 nor more than $500.00 for exceeding the 30 percent lot coverage cap, with each day of the violation counted as a separate offense under Sec. 6.20.02.A. Uncorrected violations become a declared public nuisance the county attorney can seek to abate or enjoin under Sec. 6.20.03. Property owners have 30 days to appeal a violation determination or penalty to the Board of Zoning Appeals under Sec. 6.60.05.
Frequently Asked Questions
What is the maximum lot coverage allowed in Knox County's RA zone?
Does the 30 percent limit apply to every zone in Knox County?
What happens if a building exceeds the lot coverage limit?
Do I need a permit to build an addition that affects lot coverage?
Sources & Official References
Other rules in Knox County
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