What is the minimum slope for a built-up roof?

The minimum slope for a built-up roof is crucial to ensure proper water drainage and prevent pooling, which can lead to leaks or structural issues over time. The industry standard for built-up roofing systems, which are composed of multiple layers of roofing felt and other materials, generally stipulates a minimum slope of 1/4 inch per foot (1/4:12). This slope is sufficient to allow water to flow off the roof surface effectively.

A slope steeper than this, although beneficial in facilitating drainage, is not considered necessary for a built-up roof's functionality. The 1/4:12 slope allows for adequate water drainage while still minimizing the risk of structural stress on the roof assembly. Additionally, this slope aligns with building codes and industry practices designed to maintain the longevity and integrity of the roofing system.

Other options, while they represent valid slopes, exceed the minimum requirement for built-up roofs, making them more suited for different roofing types or situations where enhanced drainage is needed. However, for the purposes of built-up roofs specifically, 1/4:12 is the recognized minimum.