DALLAS

Dallas is not one foundation market. It is several, and which one your house sits in decides most of what the repair looks like.

The older neighbourhoods. Lakewood, Munger Place, Swiss Avenue, Junius Heights and the historic pockets of Oak Cliff went up largely in the 1910s, twenties and thirties, before slab-on-grade became the default here. Homes from that era generally sit on pier and beam over a crawl space, and they fail from underneath: damp under the floor, wood softening, piers settling, and a floor that sags or bounces long before a wall shows anything.

The post-war build-out. Preston Hollow, North Dallas and the neighbourhoods that filled in from the fifties onward are slab-on-grade, and by now they carry mature trees planted with the houses. A full-grown oak draws a serious volume of water out of the ground every summer day, and the corner nearest it goes first.

The newest ground. Further north and east the houses are recent and often sit on land that was cut and filled during development. Those can show cracks a good deal earlier than their owners expect.

What all of them share is the soil. Dallas County sits largely on Blackland Prairie clay over Eagle Ford shale, some of the most expansive ground in the country. It swells when it takes on water and shrinks hard when it dries out, and the shrinking is what moves houses. Drought years do most of the damage, and they do it late: the ground keeps giving up moisture long after the rain returns, so the repair work follows the dry summer by a year or more.

We measure floor elevations across the whole house before quoting anything, because a crack tells you something happened and an elevation survey tells you what moved and by how much. Plenty of the Dallas homes we look at are inside normal tolerance for their age, and we say so.