General Contractor Practice Exam

What is the minimum grade slope required away from a building foundation?

1. 2%

2. 3%

3. 5%

4. 10%

The correct answer is: 5%

The minimum grade slope required away from a building foundation is typically 5%. This slope is crucial because it ensures that surface water drains away from the foundation, reducing the risk of water pooling near the base of the structure. Proper drainage helps prevent issues such as soil erosion, foundation settling, and water damage to the building. Adhering to this minimum slope can significantly enhance the longevity and stability of the foundation, promoting better overall drainage and mitigating possible flooding scenarios. While lower slopes like 2% or 3% may not be effective in redirecting water away fast enough, a 5% slope provides a more effective gradient for runoff, ensuring that water moves away from the foundation at a rate that significantly reduces the likelihood of water-related issues. A steeper slope, such as 10%, can sometimes be excessive for standard grading, potentially leading to erosion or other landscape management challenges. Hence, 5% is typically regarded as the minimum effective slope for drainage purposes around foundations.