Home Inspection State Practice Exam

What is the most common contributing factor to masonry retaining wall movement?

1. Soil erosion

2. Hydrostatic pressure

3. Tree roots

4. Temperature changes

The correct answer is: Hydrostatic pressure

The most common contributing factor to masonry retaining wall movement is hydrostatic pressure. This pressure builds up when water accumulates behind the wall, often due to poor drainage, heavy rainfall, or melting snow. The retained water exerts significant lateral force against the wall, which can lead to structural failure or movement if the wall is not designed to withstand such pressure or if adequate drainage provisions are not in place. Over time, this pressure can cause cracks, bowing, or even complete failure of the retaining wall. The other factors, while they can contribute to wall movement in some circumstances, are generally less significant compared to hydrostatic pressure. Soil erosion may affect the foundation and stability of the wall, but typically it is not the primary cause of movement compared to the effects of water pressure. Tree roots can potentially disrupt the structure of a wall, especially if the roots grow very close or underneath, but this is a less common cause. Temperature changes can affect materials and create expansion and contraction, but the impact is generally more minor compared to the direct force exerted by hydrostatic pressure.