A scupper is a hole through a parapet that must be lined with what material to ensure it is watertight?

A scupper is designed to allow water to drain from a flat roof or parapet. To ensure that it functions properly and remains watertight, the lining material must be durable and resistant to water exposure. Metal is typically the most suitable choice for lining scuppers because it provides a strong, non-porous barrier that prevents leakage. Additionally, metal can withstand the elements, including UV exposure and temperature fluctuations, which is critical in maintaining the integrity of the water drainage system.

Plastic, while potentially watertight, may not offer the same level of durability and resistance to environmental factors as metal. Concrete can crack over time, leading to water intrusion, and wood is not a viable option due to its susceptibility to rot and degradation when exposed to constant moisture. Therefore, metal lining on a scupper ensures longevity and reliability in preventing water leaks.