What is one common cause of issues in built-up roofing?

Water or air expansion is a common cause of issues in built-up roofing due to the nature of the materials used and the environmental conditions they are subjected to. Built-up roofing systems consist of multiple layers of waterproof materials, often including felt and asphalt, which can expand and contract with temperature changes and moisture levels. When water or air becomes trapped beneath the layers, it can lead to pressure build-up, causing the roofing material to lift, crack, or ultimately fail. This expansion and contraction must be considered during the installation process to ensure proper drainage, ventilation, and accommodation for temperature fluctuations. Failure to address these factors can result in significant long-term damage to the roofing system.

Other factors such as high installation costs, weathering elements, or improper tools used might contribute to roofing issues, but they are not as directly linked to the core functional integrity of the building materials as the effects of water or air expansion.