St. James Parish, LA Shrink-Swell Risk

What St. James Parish, LA's soil means for a foundation

Very High

USDA's SSURGO data puts St. James Parish, LA's soil at "Very High" shrink-swell potential, an area-weighted linear extensibility of 12.86% across 67.6% of the county's surveyed land. This is the reading most likely to explain cracking a homeowner is already seeing. An engineered foundation design, not a conventional footing, is the realistic expectation for new construction.

This is a county figure, not a lot figure

USDA's survey covers the whole of St. James Parish, LA at once, not any single address. A local geotechnical report, typically $1,000-$5,000 (around $2,700 typical), is the only way to know what one lot in St. James Parish will actually do.

Report cost vs. repair cost

With St. James Parish, LA rating "Very High", the gap between finding out early and finding out late is the whole decision. The report ($1,000-$5,000) is what tells you whether St. James Parish's county-level reading applies to your lot; the repair ($5,000-$15,000) is what it costs if you skip that and find out from the cracks instead.

Where this sits nationally

Nationally, St. James Parish, LA is the 4-most-constrained of 3,085 rated counties for shrink-swell soil. Within Louisiana alone it ranks 3 of 64. St. James Parish covers 238 square miles and counts 19,110 residents.

Before you act on this

Orleans Parish, LA carries this site's most-constrained reading. Lawrence County, OH and Buncombe County, NC are worth a look for comparison.

How this reading is built, and its real limits · The warning signs of expansive-clay damage, explained

More of Louisiana

Every county in Louisiana is on this site, including Morehouse Parish, LA and Tensas Parish, LA. The full underlying dataset is downloadable directly, one row per county.