How much should the grade drop within the first 10 feet to ensure surface water drains away from foundation walls?

To ensure that surface water drains away from foundation walls effectively, the grade should drop a specific amount within a certain distance. A drop of 6 inches over the first 10 feet is widely recommended because it establishes a proper slope for water drainage. This slope is essential to move water away from the foundation, preventing potential issues such as water accumulation and damage to the structure.

When the grade falls 6 inches over 10 feet, it creates a 5% slope. This slope aids in directing rainwater and runoff away from the foundation, maintaining the integrity of the building and reducing the risk of water penetration into the basement or crawl space. A slope that is too shallow may not effectively carry water away, while a steeper slope could lead to erosion or other drainage complications.

Thus, the choice of a 6-inch drop is essential for proper drainage design practices, making it the correct choice for this scenario.