What caused these brick cracks above my window?

[last goodbye]

I am thinking about buying a house but there are some vertical cracks running through the brick and mortar on the back wall, right above the center and lower corner of one window.

I know cracks like that are usually a big red flag, and I immediately thought it meant a foundation problem. But we had a foundation company come out, and they checked the house and said the foundation is fine. So, if the foundation is stable, what else could be causing these cracks in the wall? Could this just be something less serious like the brick expanding and contracting from temperature changes which is called thermal expansion? And if the foundation is truly good, should I still be worried that this is a major structural issue or is it likely just a settling or cosmetic fix?

 

[TheStoneBuilder]

Good move on getting the foundation checked first! That's step one, and it's great news that it's stable and you can likely rule out the worst-case scenario! The vertical cracks might be either due to thermal expansion like you mentioned or to a lintel issue. The lintel is the beam supporting the brick above the opening. If it's sagging, undersized, or rusting, it puts pressure on the surrounding masonry and causes these stress cracks. Since the location is right above the window, it's probably not a major structural issue for the whole house, but a localized problem. I suggest you hire a reputable masonry contractor or structural engineer to diagnose the true cause and recommend a proper fix, which might involve installing a flexible joint or addressing the lintel.