What is the purpose of a saddle in construction?

A saddle in construction serves the important purpose of facilitating the proper drainage of water off the roof, especially where there is interaction between different structural elements, like a roof and a chimney. When a roof meets a chimney, a saddle is often employed to create a sloped surface that directs rainwater away from the chimney and prevents water from pooling or running down the wall, which can lead to leaks and water damage over time.

The other options, while they pertain to various construction elements, do not accurately reflect the specific function of a saddle. Covering a door header, providing insulation, or holding the roof structure does not align with the traditional use of a saddle in roofing. Understanding this function is crucial for ensuring that roofs are adequately designed to manage water runoff, thereby protecting the integrity of the building structure.