North Carolina Building Contractor License Practice Exam

What is the minimum slope for a built-up roof excluding coal-tar built up roofs?

1. 1:20 (5% slope)

2. 1/8:12

3. 1/4:12

4. 1:12

The correct answer is: 1/8:12

The minimum slope for a built-up roof, excluding coal-tar built-up roofs, is specified to be 1/8:12. This means that for every 12 horizontal inches, the roof should rise at least 1/8 of an inch vertically. This particular slope is important for proper drainage and to prevent water pooling on the roof's surface, which can lead to leaks and other maintenance issues over time. A slope of 1/8:12 is often considered the least amount of slope that still allows for adequate drainage, especially in environments where heavy rainfall might occur. It ensures that water can easily flow off the roof rather than stagnating, which can compromise the roof's integrity and longevity. In contrast, other slopes may be applicable for different roofing systems or conditions, such as 1:20 or 1:12, but those values do not meet the minimum requirement specific to built-up roofs that exclude coal-tar options. It’s essential for contractors to adhere to these minimum slope guidelines to maintain compliance with building codes and to ensure the durability and functionality of the roofing system.