BasementSoil

“Poorly drained” soil: Saturated at or near the surface for much of the growing season

Water is removed so slowly that the soil is wet at shallow depths periodically through the year. These soils were usually farmed only after tile drainage was installed.

What it means for a basement

Assume continuous water management, not a one-time repair. Sump capacity, a backup pump and a discharge line that actually leaves the property are the load-bearing decisions. Exterior membrane work pays off here more than anywhere else, if the budget exists.

Where the USDA definition comes from

Drainage class is assigned per soil component in the national soil survey and describes frequency and duration of wet periods under conditions similar to those under which the soil formed. It is not a measurement taken at your house; it is a classification of a mapped soil body. That distinction is why we phrase every county page as a statement about soil, never as a statement about your basement.

USDA NRCS, National Soil Survey Handbook, part 618. Delivered per map unit in SSURGO.

Counties where “poorly drained” is the dominant class

213 counties in our coverage, highest-risk 60 shown.

Page data updated