Washington County, MN Building Setbacks & Zoning: Lot Coverage Limits (2026)

4 of Chapter Six, the Shoreland Management Regulations effective June 5, 2018, sets the coverage limit in one sentence: 'A maximum of twenty-five (25) percent of the lot may be covered with impervious surface. ' The chapter's Section 3 definitions confirm the scope, describing impervious surface as the percentage of the lot covered with buildings including all appurtenances, driveways and sidewalks, so a gravel or dirt driveway counts toward the 25 percent the same as a poured patio. 3. 1 requires submittal to the County Zoning Administrator, who screens for suitability including flooding risk, wetlands, and inadequate sewage capacity, factors that interact directly with how much of a lot can be hardened.

1 requires the Zoning Administrator to verify that Chapter Six's requirements, including the 25 percent cap, have been met before issuing a Certificate of Compliance for any activity requiring a building or grading permit, and the code deems any construction inconsistent with a required permit a violation of the chapter.