Expansive Soil in Vermont: County Ratings
None of the 14 rated counties in Vermont have a dominant shrink-swell rating of High or Very High. Each rating below is the NRCS shrink-swell class covering the largest share of the county's mapped soil acres, computed from USDA SSURGO data. Open a county for the full class breakdown and what it means for a slab foundation.
| County | Dominant class | High + Very High share | Survey coverage |
|---|---|---|---|
| Addison County | Low | 10% | 91% |
| Bennington County | Low | 0% | 99% |
| Caledonia County | Low | 0% | 98% |
| Chittenden County | Low | 3% | 84% |
| Essex County | Low | 0% | 99% |
| Franklin County | Low | 1% | 90% |
| Grand Isle County | Low | 27% | 86% |
| Lamoille County | Low | 0% | 98% |
| Orange County | Low | 0% | 98% |
| Orleans County | Low | 0% | 95% |
| Rutland County | Low | 2% | 97% |
| Washington County | Low | 0% | 98% |
| Windham County | Low | 0% | 98% |
| Windsor County | Low | 0% | 99% |
How these ratings are computed
Ratings come from USDA NRCS SSURGO soil survey data: for each soil component we take the maximum linear extensibility percent (lep_r) in the top 100 cm, apply the NRCS Handbook Part 618 class limits (Low under 3 percent, Moderate 3 to 6, High 6 to 9, Very High 9 and above), assign map units by plurality of component percent, and roll acres up to the county. Full details on the methodology section of the lookup page. A county rating is not a parcel-level geotechnical assessment.