A metal purlin is a lightweight, horizontal beam or bar that is used for structural support in roofing. In addition to providing support, metal purlins also increase a building’s resistance to heavy winds. Purlins are a key component to the secondary frame of commercial, residential and industrial metal buildings.

When used with roofing, metal purlins support the weight of the roof decking. This makes purlins a critical element to the structure of roofing. There are different types of metal purlins that are characterized by their shapes. We go over the most common types of metal purlins below.