National Home Inspector Practice Exam

If you observe hairline cracks in a one-year-old concrete floor with no vertical displacement, what does this indicate?

1. Insufficient reinforcement.

2. Unstable subsoil.

3. Overhydrated concrete.

4. Normal plastic shrinkage.

The correct answer is: Normal plastic shrinkage.

The observation of hairline cracks in a one-year-old concrete floor without any vertical displacement typically indicates normal plastic shrinkage. When concrete is poured, it undergoes a curing process where it loses moisture, leading to shrinkage. If the concrete was not allowed to cure properly or if it dried too quickly, fine cracks can develop due to this shrinkage. Hairline cracks are common in newly poured concrete, especially in its early stages, and they usually do not signify serious structural problems as long as there is no displacement, which means the integrity of the floor is largely intact. Understanding that these cracks often result from the natural processes associated with curing helps in distinguishing them from more significant issues that could arise from poor reinforcement or unstable subsoil. Therefore, identifying these cracks as normal plastic shrinkage indicates that the concrete is behaving as expected for its age and conditions.