What type of material is often used for vent pipes in residential plumbing?

PVC (Polyvinyl Chloride) and ABS (Acrylonitrile Butadiene Styrene) are commonly used materials for vent pipes in residential plumbing due to their properties that make them suitable for this purpose. Both materials are lightweight, easy to install, and resist corrosion, which is important in preventing deterioration over time.

PVC is particularly popular because it has a smooth inner surface that helps reduce friction and maintain proper airflow through the vent system. It is also less expensive than some metal alternatives and does not require special fittings, which simplifies the installation process. ABS provides similar benefits with slightly different chemical resistance properties, making it a viable option as well.

The other materials listed are less common for vent piping. Copper and iron can be used for other plumbing applications, but they are heavier and more costly, making them less practical for venting. Galvanized steel can also rust and corrode over time, which can hinder its effectiveness in plumbing systems. Polyethylene, while flexible and useful for certain types of piping applications, is generally not used for venting due to its lower heat resistance compared to PVC and ABS.