Had house checked by a structural engineer and it is not caused by the foundation, no cracks. Suggestion was to keep foundation watered on regular basis.

Is there a patch that will work and not pop back open?
Will it be necessary to use plywood to stabilize the ceiling?

Something does not add up.

The whole foundation will move as a single piece unless it has cracks.

Relative movement causes cracking.

Looks like I need to do further research.

Thanks.

If it is straight, it could be caused by a shifting roof truss or attic rafter.

And, how old is the house? Settling often happens in the first 3 or 4 years normally. However, settling cracks usually show up at the corners of doors/windows, not in ceilings.

Most cracks in ceilings are a truss/rafter/roofing issue.

The crack is not straight. It goes across ceiling from east side of house toward the west and a little past the middle of house it turns north. It is a long continuing crack. Did not start at a window or door corner.

Other houses in same area have the problem and were told the clay soil was causing their houses to shift. I do not know who they had to check their houses or if that was just someone's opinion. I had a professional structure engineer to check the house. He told us to water the foundation on regular basis due to the clay soil contracting and expanding.

When I used a long level in various places in the house (especially the corners and middle of house) the floors were level.

I have no idea if it works. All the information I have seen is anecdotal.

However, since other houses have the same problem, that indicates there is a soil problem.

In your case, I think I would water around the foundation---and there is probably a right and a wrong way to do that for several months and just monitor the crack. If the soil is the problem, fixing the crack not is not a long term fix, since the house might shift again.