St. John the Baptist Parish, LA Shrink-Swell Risk
St. John the Baptist Parish's SSURGO shrink-swell reading
Very High
In St. John the Baptist Parish, LA, 65.5% of the surveyed soil carries a "Very High" shrink-swell rating, 12.59% linear extensibility on average. That's the range most associated with real foundation cracking - stair-step cracks in mortar joints, sticking doors, gaps around window frames - and it typically needs an engineered foundation (post-tension slab, drilled piers), not a standard footing.
Before you rely on this for one address
St. John the Baptist Parish's reading is an average across the whole county, not a promise about any one lot inside it. The real answer for one lot is still a site-specific geotechnical report, running about $1,000-$5,000 (typically near $2,700).
Budgeting for St. John the Baptist Parish, LA
Given St. John the Baptist Parish's rating, spending a few thousand now is the way to avoid spending tens of thousands later. A geotechnical report runs $1,000-$5,000 (typically $2,700); an actual foundation repair, once cracking sets in, typically runs $5,000-$15,000 (around $10,000 typical) - roughly 4x the report.
Where this sits nationally
Among the 3,085 rated counties on this site, St. John the Baptist Parish, LA ranks 7 most-constrained nationally, and 5 of 64 within Louisiana. St. John the Baptist Parish covers 214 square miles and counts 39,694 residents.
See how another county compares
Orleans Parish, LA carries this site's most-constrained reading. Alger County, MI and Dubuque County, IA are worth a look for comparison.
How this reading is built, and its real limits · The warning signs of expansive-clay damage, explained
Elsewhere in Louisiana
Every county in Louisiana is on this site, including St. Helena Parish, LA and Calcasieu Parish, LA. The full underlying dataset is downloadable directly, one row per county.