Which is not a typical material for valley flashing?

Valley flashing is an essential component in roofing systems, primarily used to direct water away from the valleys created by intersecting roof slopes. It needs to be made from materials that are durable, weatherproof, and capable of withstanding the elements.

Roofing felt, ice and water shield, and galvanized steel are all typical materials used for valley flashing. Roofing felt serves as a base layer that helps protect the underlying structure from water infiltration. Ice and water shield is an especially effective material in areas prone to ice damming, providing a watertight seal. Galvanized steel is often used due to its strength and corrosion resistance, making it a popular choice for many roofing applications.

Composite membranes, on the other hand, are not traditionally used for valley flashing. While they can offer waterproofing solutions, they are typically employed for flat roofing systems or low-slope applications rather than the angled surfaces of a valley. Their design characteristics and intended uses make them less suitable for valley flashing in comparison to the other materials mentioned. Therefore, composite membranes are the least likely option when it comes to typical materials used for valley flashing.