What is a primary characteristic of built-up roofing (BUR) systems?

The primary characteristic of built-up roofing (BUR) systems is that they feature multi-layer waterproofing. BUR systems are composed of multiple layers of bitumen (asphalt or coal tar) and reinforcing fabrics, which are built up in alternating layers to create a robust, waterproof membrane. This layered approach not only enhances the durability and lifespan of the roof but also increases its effectiveness in resisting water infiltration and weather-related damage. The multi-layer composition provides added strength and stability, making BUR a reliable choice for various buildings.

In contrast, single-layer applications typically refer to different roofing systems that do not employ the layered technique essential to BUR's design. The installation of solar panels is unrelated to the inherent characteristics of BUR and reflects an adaptation or upgrade rather than a defining trait of the roofing system itself. Non-reinforced surfaces do not align with the built-up roofing principle, as BUR systems specifically incorporate reinforcement for improved support and longevity.