Document the condition
Note location, timing, weather relationship, changes over time, and any previous work. Photos and simple measurements can improve the first conversation.
Read the local context
Naperville's DuPage River location and its countywide clay soils shape how water moves around a foundation. Those clay soils are highly moisture-retentive, so water that can't infiltrate has to go somewhere -- often against a basement wall, through a cove joint, or up through a slab. The City of Naperville's stormwater plan leans on storm sewers, detention basins, and overflow routes precisely because the ground itself sheds water slowly, and DuPage County's floodplain rules add another layer of drainage review near mapped risk areas. Basement age matters too: older poured or block foundations built before modern damp-proofing standards behave differently than newer poured walls.
Ask what will be hidden
Roof runoff, grading, hydrostatic pressure, wall cracks, floor joints, drainage, and interior humidity can create similar symptoms with very different solutions. The written scope should explain the preparation and verification that will no longer be visible at completion.
Compare complete scopes
Look for protection, access, materials, permits, testing, cleanup, restoration, exclusions, warranties, and change-order rules.
What official local sources add
The City of Naperville is the local permitting authority for land-disturbing activity and requires property owners to maintain on-site stormwater control facilities; Naperville has adopted DuPage County's floodplain regulations for the portions of the city within DuPage County, and Naperville's own stormwater plan relies on storm sewers, detention basins, and overflow routes. DuPage County Stormwater Management enforces the countywide Stormwater & Floodplain Ordinance across five program areas -- Watershed Management, Floodplain Mapping, Water Quality, Regulatory Services, and Flood Operations -- and the county's building code requires soil testing in areas likely to have expansive clay soils.
Sources were reviewed 2026-07-26. Confirm parcel-specific flood zones, historic-district status, permits, and current requirements with the relevant authority before authorizing work.