I am inspecting a home that has a horizontal crack just along the foundation/sill plate connection. What do these cracks usually indicate???
There are no other cracks within the foundation or the structure.
Kerri
Kerri
I don’t think you will get anything other than a WILD guess without a photo.
But all horizontal cracks if large do mean something!
Does the crack look like a cold joint in the cement?..when pouring they stopped at areas, then continued when the next truck arrived?
Or is it a crack-crack…like the rebar is to close to the edge of the cement?
Could be many things, I’m just guessing without seeing anything.
As Dale mentioned without a picture I am guessing too.
From the way you worded it, sounds like the top of a foundation was out of level to a degree where they would have laid a layer of Mortar or other cementious product to bed the sill plate so as to have it level and continuously bearing.
The horizontal crack observed might be where the bed of mortar might not have bonded to the aged concrete wall.
This is all speculation and a picture would help.
Hope this helps.
Marcel 
Is it a superficial crack (surface) or does the crack go through to the exterior?
Cracks in the stucco that contour the plate-line are very common, and found in almost all structures before the advent of weep-screed. I have a build-in comment about them, but always add additional comments about the precise location, etc.
another wild guess:
Differential thermal expansion and contraction over time, since it sounds like the crack occurrs where two different materials meet.