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

Section 18.10.501 states that all development shall conform to the development standards of the zone district classifications in which the development is located as indicated in Table 18.10.501, and that the table sets only minimum standards, so stricter limits imposed by building codes, fire codes, stormwater rules or sewage disposal regulations control where they conflict. The Maximum Lot Coverage column runs from a low of 15% in the RR-5 district, the county's largest-lot rural residential classification with a 5-acre minimum lot, up to 90% in the Multiple-Family (MF) district, whose lot size is instead calculated under the separate density table at § 18.10.541.

Between those, RR-1 allows 50% coverage, RR-2 allows 30%, and both SR and UR allow 65%. The commercial and industrial districts (C-1, C-2, ML, MH) and the agricultural districts (AG, AG-38, FR) show a dash in the Maximum Lot Coverage column of Table 18.10.501, meaning the table does not set a percentage cap for those districts; coverage there is instead controlled indirectly through the district's required setbacks and any district-specific standards, such as the AG-I performance standards at § 18.10.502. A property owner calculates the allowed building footprint by applying the applicable district's percentage to the lot's total area, and must still meet the district's lot width, setback and building height standards from the same table.