Asphalt shingles base and cap flashing may be made from?

The use of corrosion-resistant metal, specifically at a thickness of .019 inches, for base and cap flashing in asphalt shingle applications is a widely accepted practice. This type of metal is favored because it provides durability and resilience against the elements, including moisture and temperature fluctuations, which are critical factors in roofing.

Corrosion-resistant metal is less likely to rust or degrade over time, ensuring that the flashing can effectively redirect water away from critical areas without compromising structural integrity or leading to leaks. The specified thickness provides a good balance between strength and flexibility, allowing for effective installation and performance under normal conditions.

In contrast, while plastic might be lightweight and resistant to corrosion, it may not provide the same level of structural support or longevity under certain environmental conditions for roofing applications. Wood can be susceptible to rot and decay, especially in moisture-laden environments, which would hinder its ability to function effectively as flashing. Fiber cement board, while durable, is not typically used for flashing due to its inconsistent performance and challenges in managing water diversion compared to metal options.