Why is aggregate used in a flood coat?

The use of aggregate in a flood coat primarily enhances durability and minimizes UV damage. When applied to a built-up roofing system, the aggregate acts as a protective layer over the asphalt, preventing it from deteriorating under the sun’s ultraviolet rays. This is crucial because prolonged UV exposure can lead to the breakdown of the roofing materials, causing the surfaces to become brittle and less effective at their job of protecting the building.

In addition to UV protection, the aggregate also helps to increase the mechanical strength of the roofing system, making it more resistant to physical wear and tear. The presence of aggregates helps distribute loads more evenly across the roof surface, prolonging its lifespan and maintaining its effectiveness over time. Furthermore, this layer improves the aesthetic appearance of the roof while also providing some additional resistance against the infiltration of water.

The other options provided, while they touch upon relevant aspects of roofing, do not accurately capture the primary function of aggregate in a flood coat. For example, while thermal insulation is a consideration in roofing systems, it is not the primary role of aggregate. Similarly, while stability for foot traffic is important, the aggregate's main function is more closely tied to durability and UV protection. Lastly, while aggregate may contribute to waterproofing in a secondary way,