An impervious surface limits water from soaking into the ground. Common examples include roofs, pavement, and concrete, though actual runoff behavior varies with material and condition. The amount and location of impervious area can affect drainage calculations and stormwater requirements. Project teams use mapping and site plans to estimate it under defined methods.
Why it matters for owners
Surface assumptions affect runoff models, permits, and site design decisions. Accurate area takeoffs support clear review.
