International Compliance Association (ICA) Home Inspector Practice Exam

What is the most common cause of wood decay?

1. Excessive exposure to moisture

2. Pest infestation

3. Improper sealing

4. High temperatures

The correct answer is: Excessive exposure to moisture

The most common cause of wood decay is excessive exposure to moisture. Wood is an organic material that naturally absorbs and retains moisture. When wood remains damp for extended periods, it creates an ideal environment for fungi to thrive. These fungi are responsible for breaking down the cell structures in wood, leading to decay and deterioration. Moisture can penetrate wood through various means, such as leaks from roofs, plumbing failures, or high humidity levels in the environment. The more moisture-logged the wood becomes, the more susceptible it is to decay, particularly in areas that are poorly ventilated or where drainage is inadequate. While other factors like pest infestation, improper sealing, and high temperatures can contribute to wood's deterioration, they are generally less significant in causing decay than moisture. Pests can damage wood but do not necessarily cause it to decay; similarly, improper sealing may allow moisture in, but the primary issue remains the exposure to moisture itself. High temperatures can affect wood treatments and promote certain fungi, but without adequate moisture, decay typically does not occur. Thus, understanding moisture's role is vital for homeowners and inspectors alike when assessing the condition of wood and implementing preventive measures.