St. Tammany Parish, LA Shrink-Swell Risk

Shrink-swell potential in St. Tammany Parish, LA

Low

Soil across 94.6% of St. Tammany Parish, LA comes back "Low" in USDA's shrink-swell data, averaging 1.93% linear extensibility. That's as favorable a county-level reading as this dataset produces - standard foundation practice, pending one lot's own geotechnical report.

What this number does and doesn't tell you

This is a countywide, area-weighted figure across every soil survey map unit in St. Tammany Parish, LA - never a reading for one specific parcel. A local geotechnical report, typically $1,000-$5,000 (around $2,700 typical), is the only way to know what one lot in St. Tammany Parish will actually do.

St. Tammany Parish: the real numbers

St. Tammany Parish's soil reading points toward standard foundation practice as the likely outcome, not the exception. A geotechnical report runs $1,000-$5,000, typically around $2,700. Foundation repair, if a specific lot turns out to differ from the county average, runs $5,000-$15,000.

Where this sits nationally

Among the 3,085 rated counties on this site, St. Tammany Parish, LA ranks 2,048 most-constrained nationally, and 58 of 64 within Louisiana. St. Tammany Parish covers 845 square miles and counts 277,615 residents.

Before you act on this

Orleans Parish, LA carries this site's most-constrained reading. Goochland County, VA and O'Brien County, IA are worth a look for comparison.

How this reading is built, and its real limits · Moisture management: the cheap fix that works on any soil

Elsewhere in Louisiana

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