Get the details down first
Note where on the Naperville property the issue shows up, when it started, how it tracks with wet or dry weather, and any prior repairs -- a couple of photos and a tape measure make that first call more useful.
Read the local context
Naperville sits entirely within DuPage County, where glacially deposited clay soils underlie virtually every lot and are described as among the most moisture-retentive in the Chicago region -- they expand when saturated and contract during dry spells, putting sustained lateral pressure on foundation walls. DuPage County's building code requires soil testing in areas identified as likely to have expansive soils and sets foundation design criteria meant to mitigate that movement. From the brick storefronts near Naper Settlement to the ranch and split-level subdivisions built through the postwar decades, the age and footing type of a Naperville-area foundation changes what a movement pattern actually means.
Ask what disappears once the work is covered
The written scope for a Naperville project should explain the prep and verification steps that vanish from view once drywall, paint, or landscaping goes back -- especially anything addressing DuPage County's moisture-retentive clay.
Set full scopes side by side
Line up Naperville-area proposals on 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. Before authorizing anything, Naperville property owners should run the parcel's expansive-clay history, historic-district status, and permit rules past the relevant authority.