Flashings on roofs should ideally be made from which type of material?

Flashings on roofs should ideally be made from corrosion-resistant metal due to its durability and effectiveness in preventing water penetration at roof joints, chimneys, and other intersections. Corrosion-resistant materials such as galvanized steel, stainless steel, or specially coated metals can withstand the elements, including moisture and UV radiation, thus minimizing the risk of deterioration over time.

The use of corrosion-resistant metal ensures that the flashings maintain their structural integrity and continue to perform their critical role in directing water away from vulnerable areas of the roof. Additionally, these materials are less likely to experience rust or breakdown, which is essential for the longevity of the roof system.

Other materials like copper are also durable but can be more expensive and may not be necessary in all applications. PVC, while useful in some roofing systems, doesn't provide the same strength and longevity for flashings as corrosion-resistant metal. Aluminum foil is not suitable for flashings since it can be too thin and vulnerable to damage, leading to potential failure in waterproofing.