In BUR, what is the purpose of a "waterproofing membrane"?

The purpose of a waterproofing membrane in Built-Up Roofing (BUR) systems is primarily to prevent water intrusion through the roofing system. This layer is crucial because it acts as a barrier that protects the underlying materials and the building structure from water damage, which can lead to various issues including mold growth, structural degradation, and reduced insulation efficiency.

The waterproofing membrane is specifically designed to withstand environmental conditions, such as heavy rain, snow, and ice, ensuring that water cannot penetrate through to the layers below. This function is essential in maintaining the integrity and longevity of the roof, making it a fundamental component of the BUR system.

In contrast, enhancing aesthetic appearance, allowing air circulation, and improving thermal insulation are not the primary roles of the waterproofing membrane. While some roofing materials may incorporate features that contribute to aesthetics or insulation, the waterproof barrier's main objective is to provide a reliable defense against water infiltration.