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

BMC 12.14.140 supplies the definitions behind Bothell's coverage limits. Building coverage is the portion of a lot occupied by the principal building and its accessory buildings, including all projections except eaves, expressed as a percentage of total lot area. Decks are exempt. Hard surface coverage is the ground area of the entire development site covered by any impervious surface, permeable pavement or vegetated roof, found by projecting vertically to the ground from the widest points of any hard surface. Permeable pavement and vegetated roofs count only 50 percent of their site area for purposes of the development standards tables in BMC 12.14.030 and 12.14.040.

The residential table sets the maximum hard surface coverage by zone: 35 percent in R-C, 55 percent in R-L1, 60 percent in R-L2, 70 percent in R-M1, 75 percent in R-M2, 80 percent in R-M3, 90 percent in R-M4 and 80 percent in R-AC. The area within the front yard setback cannot contain any hard surface except driveways, walkways and structures allowed to project into the setback under BMC 12.14.090. Within the front yard setback, driveways can be no wider than necessary to accommodate three vehicles across, and walkways cannot exceed five feet in width.

Several notes adjust the numbers. Hard surfaces legally established before December 31, 2016 that exceed the limits fall under the nonconforming provisions of Chapter 12.26 BMC. On a panhandle lot, coverage is measured as though no handle were on the lot. A duplex, triplex or fourplex can increase maximum hard surface coverage by 10 percent, subject to the conditions in the notes. Where critical areas are present anywhere on the property, impervious surface coverage is further regulated by BMC Title 14. Accessory buildings carry a separate five percent of lot area limit under BMC 12.14.130.