Vertical crack in the foundation- how big a deal is this?

[Lee Lewis]

Investigating a property in the mountains for a househack deal, and in the disclosures we found a vertical crack in the foundation. I remember on the BP podcast hearing someone advise just stay away from any cracks in the foundation (automatic pass). However, reading on the internet, it seems like vertical cracks are very common and most homes have 1-3 after a few years post-construction (T/F?). WHAT DO YOU THINK, and what follow up questions and inquiries need to be investigated?

[Russ B.]

It depends on the crack, and the type / amount of movement that caused it. It also depends on the age of the building and of the crack. You can usually tell from the location and direction of a crack, what caused it. 

For example, a crack of 1/8 inch in a 50 year old basement wall, near where the house meets an attached garage, would almost certainly not be bad - especially if you can see that the last couple coats of paint got inside it. On the other hand, a 1/2-inch crack in a brand new building would indicate a major problem...