At what spacing should a purlin typically be installed?

Purlins are horizontal members that support the roofing and are typically installed on a slope for proper water drainage and structural integrity. While the choice of spacing for purlins can vary depending on specific building codes and types of roofing materials, it's common practice to install them at every rafter. This placement provides consistent support for the roofing material, ensuring that there is no sagging or distortion, which can lead to structural failure or leaks.

The frequency of installing purlins at every rafter adheres to the structural needs and safe loading considerations of the roof, especially in areas subject to high winds or heavy snow. By providing a continuous support line, purlins enhance the overall load-bearing capacity of the roof system.

Other spacing options such as 4 ft on center or 24 inches on center might be methodologies for specific applications or materials but don’t universally apply to all roof structures. Installing a purlin at every rafter addresses the major concern of adequate support across varying loads and ensures compliance with best practices in roofing construction.