Oregon Construction Contractors (CCB) Practice Test 2025 - Free CCB Practice Questions and Study Guide.

The purpose of foundation walls in relation to basements primarily involves protecting against water penetration. Foundation walls are constructed to bear the weight of the structure above while forming a barrier that can keep moisture from the surrounding soil out of the interior space of the basement. This is significant because water intrusion can lead to various problems, including mold growth, structural damage, and the degradation of building materials over time.

Effective foundation walls often incorporate drainage systems and waterproofing measures to enhance this protective function, ensuring that any water that does reach the walls is channeled away from the structure. While the other choices may play roles in other aspects of construction, they do not capture the core function of foundation walls in the context of basements as effectively as the correct answer does.