The primary purpose of a rafter in roofing is to support the roof structure. Rafters are structural members that create the slope of the roof and carry the weight of the roof covering, snow, and any additional loads, ensuring stability and durability. They help transfer the load down to the walls of the building, which is essential for maintaining the overall integrity of the structure.
While insulation, aesthetic appeal, and moisture protection are important considerations in roofing design, they are not the primary functions of rafters. Insulation is typically added separately, aesthetic features can be enhanced through other design elements, and moisture protection is primarily the role of roofing materials and underlayment. Therefore, the support function of rafters is fundamental to keeping the entire roofing system safely in place.