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

The dimensional standards table in RMC § 23.18.040 sets Maximum Lot Coverage at 40 percent for the R-1-12, R-1-10 and R-2 single- and two-family districts, and raises it to 50 percent in R-2S, the medium-density small-lot district built for more compact development. R-3, the multiple-family district, carries a split standard under table note 9: buildings generally cannot cover more than 33 percent of the lot, but one-family attached dwellings, that is, townhouse-style units, may cover up to 45 percent. Table note 8 defines what counts toward the cap: coverage includes all buildings, including accessory buildings or structures, on any residential lot, but excludes patios that have no roof or that carry only an open lattice or similar roof.

Table note 10 applies the R-2S figures, rather than the separate R-3 numbers, to one-family attached, one-family detached and two-family detached development built inside an R-3 district, so the 33/45 percent split reaches only true multifamily construction. The coverage limit works alongside RMC § 23.08.090, which bars any building site from being altered, enlarged or having its open space reduced except in conformity with the area and yard regulations set for its use district.