What material is often used for drainage systems around foundations?

Gravel is commonly used in drainage systems around foundations due to its ability to facilitate water movement and drainage. Its structure allows water to flow through, preventing accumulation around the foundation that can lead to water damage or structural issues. The voids between gravel particles create channels for the water to move away efficiently, ensuring that moisture does not seep into the foundation walls.

Additionally, gravel is durable and can withstand environmental changes without degrading, making it a reliable choice for long-term drainage solutions. It also allows for effective filtration, helping to prevent the ingress of soil and debris into the drainage system. This effectiveness at managing water flow is why gravel is typically preferred over other materials like plastic sheeting, cement, or wood chips for this specific application.