Which feature is essential for effective drainage at a building site?

Adequate slope away from the foundation is essential for effective drainage at a building site because it helps direct water away from the building, preventing pooling and reducing the risk of water damage to the structure. Proper grading is crucial; if the ground slopes towards the foundation, it can lead to flooding in basements, increased humidity, and potential structural issues over time. Ensuring that the landscape has a sufficient slope away from the foundation establishes a natural pathway for stormwater to flow away from potentially vulnerable areas.

While installed insulation, waterproof walls, and ground cover plants may contribute to a building's overall protection against moisture, they do not directly address the critical aspect of drainage. Insulation is beneficial for energy efficiency and comfort, waterproof walls are designed to prevent water infiltration, and ground cover plants may help with erosion control, but none of these features actively manage the water flow away from the structure as effectively as proper site grading does.