What type of roof uses purlins?

Answered by Edward Huber

Purlins are commonly used in various types of roofs, including metal buildings and wood-frame structures. In metal buildings, purlins are essential components that support the roof panels. They are typically installed horizontally, parallel to the building’s ridge, and are attached to the primary structural frame.

Metal buildings are often designed with a rigid frame system consisting of columns, rafters, and purlins. The purlins provide additional support and stability to the roof structure. They help distribute the weight of the roof panels evenly and prevent sagging or deflection.

Wood-frame structures, on the other hand, may also utilize purlins instead of closely spaced rafters. In this case, the purlins serve as intermediate supports for the roof sheathing or panels. They are typically installed perpendicular to the rafters and span between them. This design allows for wider spacing between rafters, reducing material and labor costs while maintaining structural integrity.

I have personally worked on projects involving both metal buildings and wood-frame structures that utilized purlins. In a metal building project, we had to carefully install the purlins to ensure they aligned with the roof panel attachment points. This required accurate measurements and precise installation techniques to avoid any issues with the roof’s performance.

In a wood-frame structure, we used purlins to support the roof sheathing, which was made of plywood. This allowed for wider spacing between rafters and reduced the overall weight of the roof. It also provided a solid base for the roof covering, ensuring it remained secure and protected from weather elements.

To summarize, purlins are commonly used in metal buildings to support roof panels and in wood-frame structures as an alternative to closely spaced rafters. They play a crucial role in distributing the weight of the roof and maintaining its structural integrity. Whether it’s a metal building or a wood-frame structure, the use of purlins offers cost-effective solutions and efficient roof designs.