What is the purpose of rafter ties in a roof system?

Rafter ties play a crucial role in maintaining the structural integrity of a roof system. Their primary purpose is to stabilize the structure and prevent sagging. By connecting opposing rafters at their lower ends, rafter ties help distribute the load and counteract the outward thrust caused by the weight of the roof. This ensures that the roof maintains its intended shape and supports the overall stability of the building. Over time, without adequate rafter ties, roofs can experience sagging or bowing, which may lead to more serious structural issues.

Other functions you might consider, such as supporting heavy roofing materials or holding insulation in place, do not accurately encompass the main function of rafter ties. Additionally, while aesthetics can be a consideration in roof design, rafter ties are primarily structural elements rather than design features.