Questions & Answers about Tenemos una grieta pequeña en la pared del baño.
Because tenemos means we have, while hay means there is/there are.
- Tenemos una grieta pequeña en la pared del baño = We have a small crack in the bathroom wall
- Hay una grieta pequeña en la pared del baño = There is a small crack in the bathroom wall
Both can be natural, but they are slightly different in focus:
- tenemos focuses on our situation/problem
- hay focuses on the existence of the crack