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Stormwater

Impervious surface

Impervious surface affects drainage, stormwater rules, heat, and sometimes permitting. Cities may limit how much of a lot can be covered or require mitigation such as permeable pavers, drains, or planting areas.

Definition

Impervious surface is hardscape or roofing that prevents water from soaking naturally into the ground, such as concrete, roofs, patios, and some driveway materials.

Why it matters

Outdoor projects should account for runoff before adding large patios, driveways, pool decks, ADUs, or roofed structures.

Also called

non-permeable surfacelot coveragehard surface