All districts
Accessory uses must be customarily incidental and subordinate to the principal use. Detached accessory structures in residential districts are capped by parcel size: 600 sq ft up to 15,000 sq ft of lot, 800 sq ft up to 1 acre, 1,200 sq ft up to 3 acres, 1,500 sq ft up to 5 acres, and 2,400 sq ft above 5 acres (footprint only). In commercial and industrial districts the cap is 10 percent of the principal structure's floor area up to 5,000 sq ft. Residential district use lists also require accessory buildings to sit in the side or rear yard at least 5 ft from any lot line. Agricultural accessory structures of any size are allowed on parcels of at least 15 acres with 10 ft side and rear setbacks. Overlays, planned-development approvals, recorded conditions, and Article VI exceptions can change the parcel-specific result; confirm with Smyrna Planning and Zoning before relying on this answer.