Gap between slab and stem wall

I observed a 1/2" gap between a slab floor and the stem wall. It is about 20’ long and runs most of the width of the house. You can clearly see the stem wall through the gap. There are no cracks in the stem wall, the walls, the ceiling, or windows. There appears to be some heaving as the slab is about 1/4" above the bottom of the baseboard trim in the center. There are only a few hairline cracks in the slab, although the house is carpeted so only the immediate area was observed. The tile floor in the kitchen along the shared wall is okay. Is this a structural issue or slab shrinkage, or heaving from expansive soil? A contractor friend suggested that the stem wall settled, but I didn’t see any visible cracking of the stem wall. We do have expansive soils in Phoenix but this is the first time I’ve seen the slab raised. Any suggestions are appreciated.

James

Just from your description I agree with your contractor. Your concrete slab would not shrink enough to account for a 1/2" gap. I just finished doing a structural inspection on a house with a similar problem. You will probably need someone with structural/geotechnical experience along with your contractor to figure this one out. Good Luck…

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I saw the same thing a couple of weeks ago in a house in
Goodyear, AZ., except it was confined to garage slab and the slab was level with stem wall. Looked like it had been that way since built. Took some pictures and wrote it up as a settlement gap.