What is a common issue discovered in a 90-year-old home basement when there is a large tree nearby?

A common issue observed in a 90-year-old home's basement, particularly with the proximity of large trees, is the presence of diagonal cracks caused by tree roots lifting the footing. This phenomenon occurs because as the tree roots grow, they can exert pressure on the foundation of the home, particularly if the roots are aggressive and seek moisture. The growth of the roots can disturb the soil around the foundation, leading to settlement or lifting that manifests as diagonal cracks in the basement walls.

In older homes, which often have less robust foundations compared to modern standards, this type of structural movement can be significant. Addressing these cracks is crucial, as they can lead to further issues, such as water intrusion or compromised structural integrity if not managed promptly.

While water leakage, mold growth, and old wiring are certainly concerns in older homes, they are not directly linked to the condition of having a nearby large tree as the primary cause, making diagonal cracks from root growth a more specific and relevant issue in this context.