You patched it, sanded it, painted it, and within a year it is back in exactly the same place. That is almost never a patching failure. It is the ground under the house.
San Antonio sits on clay that moves
Much of the metro sits on expansive clay soils. Clay takes on water and swells, then dries out and shrinks. In a climate that alternates between long dry spells and heavy rain, that cycle runs every year, and the slab on top of it moves with it.
The movement is small. It is also relentless, and drywall is a brittle sheet nailed to a frame that is being flexed. It gives at the weakest points, which are always the same places.
Where the cracks appear tells you what is happening
Diagonal cracks running up from the corners of door and window openings are the classic signature of frame movement. Those corners are where the sheet is cut, so they are where the stress concentrates.
Long horizontal cracks along a ceiling to wall joint are usually seasonal, opening in one part of the year and closing in another. Vertical cracks in the middle of a wall often follow a seam that was not taped properly in the first place, and those are genuinely a repair problem rather than a soil one.
Doors are the tell that costs nothing to check. If a door that used to close now catches at the top corner, or the latch no longer lines up with the strike, the opening is out of square. That is why door adjustment and drywall repair so often turn out to be the same job.
What actually stops it coming back
Cutting back to solid board, taping properly with mesh or paper rather than filler alone, and texture matching so the repair disappears will hold far longer than a smear of compound. But it is still a repair to a symptom.
The thing that reduces the movement is water management. Keeping soil moisture even around the slab through the dry months, and getting roof water away from the foundation in the wet ones. That second part is why gutter work is a foundation issue as much as a roof one, and why a blocked downspout dumping water at one corner of the house for two seasons shows up as a crack in the hallway.
Older housing stock feels this more. The 1950s to 1970s slab on grade homes across Kirby, Converse and Universal City are the ones we see it in most, and pre war construction in Alamo Heights moves differently again because the wall build up is not the same.
When it is not cosmetic
Call a structural engineer, not a handyman, if a crack is wider than about a quarter inch, if it runs through brick or block outside as well as drywall inside, if it is stepping diagonally through mortar joints, or if floors have visibly sloped. Those are foundation questions and patching them is hiding evidence.
Everything narrower than that, appearing at openings, opening and closing with the seasons, is ordinary and repairable. Repair it properly, fix the drainage, and it will stay closed a great deal longer.
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