WYLIE

Wylie grew very fast in the two thousands, on Blackland clay, and much of it on land that runs down toward Lake Lavon.

Fast growth on sloping ground means cut and fill: level building pads carved out of a slope, with the cut side on original compacted ground and the fill side on soil that was placed there.

A house sitting across that line has two different foundations under one slab whether the builder intended it or not, and the boundary is where the movement usually shows up.

What the ground under Wylie is actually doing

Wylie is Blackland through and through. Houston Black covers over a fifth of the city at a linear extensibility of 12.7 and 54% clay, with Heiden at 13.6 and Burleson at 7.7 making up much of the rest. There is no calm corner of Wylie to speak of.

To put that in perspective, the ground under Wylie swells roughly ten times as much as the ground under Southlake, thirty miles west. Both are Dallas-Fort Worth addresses; they are not the same engineering problem, and a contractor who quotes them the same way is not paying attention.