Kennewick, WA Building Setbacks & Zoning: Lot Coverage Limits (2026)

Lot intensity in Kennewick is regulated through a combination of minimum lot size, unit density, setback, garage setback and height standards in KMC 18.12.010 A.2 (Table of Residential Site Development Standards), rather than a single maximum building or impervious coverage ratio by district. The 2023 middle-housing update (Ord. 6007) and 2024 Ord. No. 24-6074 substantially rewrote the residential standards: minimum lot size dropped to 8,000 sf in RS, 5,500 sf in RL, 4,000 sf in RM, 3,500 sf in RH, 1 acre in RTP and 5,500 sf in RMH; minimum townhouse/rowhouse lot size is 1,800 sf (1,600 sf in RTP); unit density on a single lot is up to 4 units in the RS, RL, RMH, RM and RH zones, with up to 6 units permitted if at least two units qualify as affordable housing under the criteria in KMC 18.12.010 A.2(1)(a)(ii) (rental at 60% AMI / owner-occupied at 80% AMI, maintained affordable for at least 50 years under a recorded covenant per Chapter 84.14 RCW). The required setback envelope (15-foot front, 5-foot side, 15-foot rear) effectively constrains the maximum buildable footprint. The State Building Code (WAC 51-50, 2021 IBC Chapter 5) layers maximum building area limits based on construction type and occupancy class. Impervious surface and stormwater coverage are regulated through Kennewick's Frontier and West Richland-area Stormwater Code in Chapter 4.30 KMC and the City's adopted manual aligned with Washington Department of Ecology stormwater standards. Variances follow the Title 18 administrative process. State authority is RCW 35A.63 (Planning Powers).