Performance issues related to glass fibers can include:

The correct answer highlights a key aspect of glass fibers in construction and roofing materials. Glass fibers can be prone to performance issues such as cracking and breaking over time, particularly if they are subjected to stress, impact, or adverse weather conditions. This brittleness can significantly affect the durability and longevity of roofing materials that incorporate glass fibers. Understanding this weakness is crucial for contractors and builders, as it informs decisions regarding material selection and the design of roofing systems to mitigate these issues.

On the other hand, the other choices suggest attributes that do not align with the performance problems associated with glass fibers. Improved UV protection and increased waterproofing are desirable characteristics of roofing materials, but they do not specifically relate to performance issues concerning glass fibers. Similarly, while lower weight can be advantageous in certain applications, it is not inherently a performance issue but rather a characteristic of the material that can influence how it is used in roof systems.