HomeFoundation Soils vs Web Soil Survey
Foundation Soils vs Web Soil Survey
Foundation Soils · checked October 6, 2026
Web Soil Survey is the USDA NRCS web app for soil maps and data produced by the National Cooperative Soil Survey. Foundation Soils is a reference site built from public data: soil, water table, drought and flood losses for the ground under US houses. They overlap, but they answer different questions. Use Web Soil Survey when you need soil map units for one lot or a custom area. Use Foundation Soils when you want expansive clay, water table, drought and flood losses for a county, city or ZIP on one page.
Foundation Soils is a reference site that earns referral fees, so read its side of this page with that in mind. Every fact about Web Soil Survey below was read from its own pages on October 6, 2026 and links to the page it came from.
Side by side
"Not on the pages read" means the page we read did not show it, not that the site lacks it. Checked October 6, 2026. Prices and counts change; check the linked page.
When Web Soil Survey is the better pick
- You need the soil map units for one specific lot. You outline the lot; the other sites on this page stop at the county, ZIP or city.
- You want to download the soil data or print a report for an area of your own.
- You need the survey itself. Most of the other sites here are built from the same USDA soil survey data, so Web Soil Survey is the original they summarize.
When Foundation Soils is the better pick
- You want a ZIP, county or city page that already adds the soil, the water table, this week's drought map and FEMA flood losses, with no map to outline and no tabs to click through.
- You want a plain share: how much of a county's mapped land USDA rates a limit for slab homes, and how much for basements.
A county or ZIP page here is a starting point. The soil under one lot can differ from its county, and what to do about a house is a question for a licensed engineer.