What is the minimum slope for a bitumen roof?

The minimum slope for a bitumen roof is indeed 1/4:12. This specific slope is crucial for ensuring proper drainage and preventing water accumulation, which can lead to leaks and damage over time. A slope of 1/4:12 indicates that for every 12 horizontal inches, the roof rises 1/4 of an inch, providing adequate drainage while maintaining performance standards for bitumen materials.

A flatter slope, such as 1/8:12, may not provide sufficient run-off, potentially causing ponding water issues, which can compromise the integrity of the roofing materials and lead to premature failure. Conversely, steeper slopes like 1/3:12 and 1/2:12 exceed the requirements, which can influence the installation methods and drainage patterns but are not necessary for the basic performance of a bitumen roof. Thus, 1/4:12 is the optimal minimum slope considered adequate in the North Carolina Residential Code.