Plaquemines Parish, LA Shrink-Swell Risk

What Plaquemines Parish, LA's soil means for a foundation

Very High

USDA's SSURGO data puts Plaquemines Parish, LA's soil at "Very High" shrink-swell potential, an area-weighted linear extensibility of 11.41% across 63.3% of the county's surveyed land. 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.

This is a county figure, not a lot figure

USDA's survey covers the whole of Plaquemines Parish, LA at once, not any single address. A site-specific soil report, usually $1,000-$5,000, is what an engineer would actually pull before designing a foundation on a lot in Plaquemines Parish.

Report cost vs. repair cost

Plaquemines Parish's soil reading is exactly the case where a report before construction, or before cracks widen, pays for itself. The report ($1,000-$5,000) is what tells you whether Plaquemines 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.

Plaquemines Parish's rank among Louisiana counties

Nationally, Plaquemines Parish, LA is the 16-most-constrained of 3,085 rated counties for shrink-swell soil. Within Louisiana alone it ranks 11 of 64. The county spans 781 square miles, home to 22,289 people.

Before you act on this

Orleans Parish, LA carries this site's most-constrained reading. Montgomery County, MD and Adams County, IN 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 St. Martin Parish, LA and St. James Parish, LA. The full underlying dataset is downloadable directly, one row per county.