Impervious cover is any type of man-made or stone surface that doesn’t absorb rainfall.
Surfaces such as stone, rooftops, patios, driveways, sidewalks, roadways, parking lots, and some decks are considered impervious cover. Uncovered wooden decks count as 50% impervious cover.
Impervious cover does not include sidewalks or easements in the public right-of-way, water features such as ponds, pools, fountains, and non-compacted areas with gravel used only by pedestrians.
Dependent on zoning designation, a certain percentage of impervious cover is permitted on a property. Download this spreadsheet to assist you with calculating impervious cover.
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