When using mineral surface roll roofing as a valley, the top layer must be at least how many inches?

The correct response indicates that when using mineral surface roll roofing in a valley application, the top layer must extend to a minimum of 36 inches. This requirement is designed to ensure adequate protection and performance of the roofing structure in a valley, which is an area prone to increased water runoff and potential collection of debris.

Having the top layer at 36 inches allows for sufficient overlap and coverage in the valley, reducing the risk of leaks caused by inadequate material or improper water management. The size helps to create a robust barrier against water infiltration and contributes to the longevity of the roofing system.

This specification is rooted in established roofing practices and is part of ensuring compliance with building codes that promote structural integrity and safety. In contrast, lower measurements may not provide the necessary coverage to effectively manage runoff, thereby increasing the likelihood of water damage or failures over time.