Franklin County, WA Building Setbacks & Zoning: Structure Height Limits (2026)

050(E) of the Franklin County Code sets a 35-foot height limit for both primary and accessory structures in the AP-20 agricultural production zone, the county's 20-acre-minimum farmland district. 050(F), so the number carries across the county's agricultural and larger-lot residential zones even though minimum lot sizes differ sharply between them. The AP-20 height rule carries two carve-outs. First, the limit doesn't apply to barns, silos, water towers or other farm buildings and structures, recognizing that grain storage, hay barns and irrigation infrastructure routinely exceed a standard two-story roofline.

Second, it doesn't apply to projections not used for human occupancy, specifically chimneys, domes, spires, elevator shaft housings, towers, aerials and flagpoles, so a farmhouse can add a chimney or a property owner can erect an antenna without triggering a variance. Because the exemption is written around farm buildings and non-occupied projections rather than a blanket exemption for accessory structures, a pole barn used as a workshop or a detached garage built for human use still has to stay within the 35-foot cap unless it independently qualifies as a barn or similar farm structure. A landowner planning a tall grain elevator or water tower on AP-20 land doesn't need a height variance; one planning a two-and-a-half-story workshop does.