What makes it difficult to identify flaws in the membrane of a built-up roof?

The challenge in identifying flaws in the membrane of a built-up roof primarily stems from the gravel coating that is often applied on top. This gravel serves several purposes, such as protecting the underlying materials from UV rays, providing additional weight to hold the roof down, and helping to manage water runoff. However, the gravel also obscures the membrane from view, making it difficult for inspectors to visually assess for any damage, wear, or other issues that may be present beneath it.

While other factors like poor weather or multiple layers could contribute to some degree of difficulty in inspection, the actual concealment of the membrane by the gravel coating is a direct barrier to an accurate assessment. Without removing this layer, an inspector cannot properly evaluate the membrane's condition or identify any potential flaws that could lead to leaks or structural issues.