North Carolina Building Contractor License Practice Exam

What slope is required for a minimum distance of site grading away from a building?

1. 1:50 (2% slope)

2. 1:20 (5% slope)

3. 1:40 (2.5% slope)

4. 1:30 (3.3% slope)

The correct answer is: 1:20 (5% slope)

The minimum slope required for site grading away from a building is crucial for effective drainage and to prevent water from pooling around the foundation. A slope of 1:20, which translates to a 5% grade, is commonly recommended in these situations. This gentle incline ensures that water moves away from the structure efficiently, minimizing the risk of water damage to the foundation and surrounding areas. This slope is effective because it strikes a balance between being steep enough to promote drainage while not being so steep that it becomes difficult to manage or creates erosion issues. A 5% slope allows for good movement of rainwater or runoff without causing rapid erosion or making the area uncomfortable for landscaping or foot traffic. In contrast, the other slope options are less effective for significant drainage needs. A slope of 1:50 (2% slope), for instance, is often insufficient for redirecting water effectively, making it prone to pooling near structures. The 1:40 (2.5% slope) is slightly better, but still not ideal for ensuring adequate water diversion. Lastly, a slope of 1:30 (3.3% slope) offers better drainage than the lower percentages but does not meet the optimal recommendation of 1:20 for most construction standards,