Location comes first
The checker is intentionally limited to the contiguous United States. The Census geocoder provides approximate matches. You confirm the returned address before we query soil properties. Coordinates and map boundaries can still differ from the building you intended to investigate. A coordinate is not a parcel survey.
The soil mixture stays visible
SSURGO returns map units and their components. A component share describes a map-unit mixture, not measured shares of a yard. We highlight a unique largest component only when one map unit is returned and the largest share is not tied. An unrated largest component is not replaced by a smaller rated one.
Depth and screening bands
For each component we read horizons intersecting 0–100 cm and show the maximum reported representative linear-extensibility value. The bands are Low: less than 3%; Moderate: 3% to less than 6%; High: 6% to less than 9%; Very high: 9% or more. This is our screening summary, not a foundation-design rating. Rated depth is the union of reported intervals clipped to 0–100 cm; gaps stay unknown and overlapping intervals count once.
County drought is regional context
Up to nine published weeks are shown. D1 means county area in moderate drought or worse. D0–D4 statistics are cumulative, so they overlap and must not be added. Four-week change is the D1-or-worse area difference from a map 28 days earlier, with three days of tolerance. We use percentage points, never a property-risk change. Data over 14 days old are labeled stale, including when you reopen a snapshot.
Comparison rules
Soil time comparisons require exactly matching coordinates rounded to six decimals. Drought change requires the same county, valid percentages and a strictly later map date. A different county, the same week or an older current map produces an explanation instead of a misleading change figure. A changed mapped value is not proof of measured soil movement.
Your notes stay separate
The inspection notebook holds observations you enter, not diagnoses we infer. It works in the browser. Nothing is saved permanently until you press Save on this device. JSON and CSV export are user actions. A photo reference is only a filename or description; photographs are not uploaded.
No-data handling and scope
Provider outages, no coverage, unrated components and ambiguous map boundaries remain distinct. We do not measure soil moisture, subsidence, erosion, slab movement, cracks or plumbing. Significant or sudden building changes warrant appropriate local assessment regardless of an online map.
Reproducibility
Reports retain coordinates, source references, map units, layer values, weekly drought data and retrieval times. Source and retrieval dates are different. The original survey or a qualified site investigation may contain information that this screening does not. Read the source register and report reproducible presentation issues through Contact.
Sources and interpretation
USDA NRCS linear-extensibility definitions
Explanations and workflow are our own. This is educational screening, not a site investigation or engineering recommendation.