What is the role of collar ties in construction?

Collar ties play a critical role in maintaining the structural integrity of roof systems, specifically in preventing rafter sag. Located high in the roof structure, collar ties connect the opposing rafters together. This connection helps to resist the downward forces that are exerted on the rafters due to the weight of the roofing materials, as well as environmental loads such as snow.

When rafters are not adequately supported, they can start to sag due to the weight they carry, which can lead to structural issues and even failure. By stabilizing the rafters in this way, collar ties help ensure that the roof maintains its intended shape and that the load is distributed more evenly. Proper installation of collar ties is essential for preventing sagging and ensuring the longevity of the roof structure.