I live in a split-level house built in the '70s. After moving in a few years ago we discovered a leaking crack in one of the basement walls. The walls are concrete. The crack is diagonal/vertical, extending down from the corner of the foundation where the fourth level of the house steps down into the fifth (lowest) level. The top of the crack is a little wider and slightly laterally displaced.

Coinciding with the foundation crack are vertical drywall cracks on the fourth and third levels of the house. The cracks are parallel to one another and to the foundation crack (if I measured they would all be 20 feet or whatever from the corner of the house).

The drywall cracks have recurred after re-mudding. We had the basement crack repaired by injection but it has cracked again in the exact same pattern.

Any ideas on what is going on here? Soil expansion? We live in the Edmonton area of Alberta, Canada. Is this going to be a super expensive kind of thing to fix?