What is the purpose of collar ties in roofing?

The purpose of collar ties in roofing is to prevent rafter spread. Collar ties are horizontal members that are installed between rafters in a roof structure, typically situated in the upper one-third of the roof slope. They are designed to help maintain the structural integrity of the roof by resisting outward forces that can occur due to the weight of snow, wind loads, or the pressure from the roofing materials. By tying the rafters together at a higher point, collar ties help keep them from spreading apart, which can lead to a compromised roof structure and potential failure. This is particularly important in sloped or rafters structures, where maintaining the alignment of the roofing system is crucial for both stability and overall performance.