Regarding hillside houses with foundation drain systems, what is true?

The assertion that foundation drain systems collect water passing laterally through the slope is accurate and reflects a fundamental principle of how these systems function in hillside structures. In areas with sloped terrain, water can infiltrate the soil from above and be directed laterally towards the foundation of a home. Foundation drainage systems are designed to intercept this water, preventing it from building up around the foundation and causing potential issues such as soil erosion, hydrostatic pressure, or flooding in basements.

These drain systems are typically positioned at the base of the foundation wall and rely on gravity to channel the water away, often directing it to a drainage system or storm sewer. This proactive design helps maintain the integrity of the structure by mitigating moisture problems that could lead to structural damage or mold growth.

The other options do not accurately describe standard practices or requirements regarding foundation drain systems for hillside houses. For example, while there are specified materials for drainage systems, it is not true that all must use perforated plastic piping. The principle behind roofing drainage systems typically points to separating them from foundation drains to prevent overload and potential clogging issues. Additionally, rock-filled foundation drains can be permissible in certain contexts but may not be advisable or effective when installed on the interior side due to risk of clogging