Final answer:
Cracks in foundation walls can be caused by thermal stress from temperature changes, shrinkage of materials over time, differential settlement of the foundation, and external loads or pressures imparting stress.
Step-by-step explanation:
The causes of cracks in foundation walls can often be attributed to a variety of stressors. While the question addresses the foundation walls specifically, understanding the broader context of how materials react to environmental factors can provide insight into this issue. Here are four key causes:
- Thermal stress: Just as railroad tracks and roadways can buckle in hot weather without expansion joints, a foundation wall can develop cracks due to the expansion and contraction that comes with temperature changes.
- Shrinkage in materials: Materials such as concrete can shrink over time as they cure and lose moisture, leading to crack formation.
- Differential settlement: If different parts of a foundation settle at different rates, it can lead to cracking. This settlement can be due to variations in soil strength, moisture content, or loading.
- External loads and pressures: Changes in earth pressures, heavy loads from above, or even impacts can induce stresses that result in cracking.