If “doming” (fn) is a serious problem during dry seasons for anybody who’s built on Las Colinas Tufa… and if clay soils all over Texas are an issue… why not just insert a cheap plastic barrier into the soil when the concrete’s being poured?  It’ll move around some as the soil does, but it would keep the moisture under said foundation much more consistent, and the total cost to the builder would probably be less than a hundred dollars.

Even after the fact, you could do this with several days of serious soaker-hosing, combined with a good drenching, and do this with nothing cobbled together from Home Depot or Lowe’s.

This seems like a no-brainer to me.  Is it, or am I stuck on stupid and missing something important?

(fn)– defined to me by my buddy Phelonius as what happens when moisture collects in the soil under center of the foundation while the ground all around the edges are drying, thus producing serious foundation stresses as half of it expands and pushes up on the concrete, and the other half contracts, thus “pulling” it down.