What is the maximum span of 2" X 4" purlins in conventional light-frame construction?

In conventional light-frame construction, the maximum span of 2" X 4" purlins is 4 feet. This span is determined based on various factors including the load that the purlin will support, material properties, and building codes.

Purlins are horizontal structural elements typically used to support roof structures, transferring loads to the walls and ensuring structural integrity. When spanning distances greater than the recommended limits, there is an increased risk of deflection and structural failure under load.

The span of 4 feet allows for adequate support while maintaining the rigidity necessary to prevent collapse or excessive sagging. This distance is generally accepted by building codes and engineering practices, ensuring safety and durability in construction. For reference, spans beyond this distance would likely compromise structural performance, hence the selection of a 4-foot maximum span reflects adherence to standard engineering guidelines.