What matters for project planning
Two of the city's requirements bear directly on below-grade work. Naperville requires property owners to maintain on-site stormwater control facilities, which is the question a waterproofing proposal has to answer: a system that collects water at the foundation must discharge somewhere the stormwater plan actually anticipates, not simply a few feet from the wall. And because the city's plan relies on detention basins and overflow routes, a property's position relative to those routes explains a great deal about why water arrives when it does. Where the parcel sits within DuPage County, the county floodplain regulations Naperville has adopted apply on top.
Official sources
Verify the property, not just the city
Citywide context cannot establish a parcel’s flood zone, historic designation, permit requirements, soil conditions, or concealed construction. Confirm those specifics with the appropriate Naperville authority and the selected provider before work begins.
Last checked 2026-07-26 -- external requirements and mapped boundaries may since have changed.