What is the purpose of a cornice in roofing practice?

The purpose of a cornice in roofing practice is primarily to provide a weatherproof cap for walls. This architectural feature extends beyond the wall or eaves of a roof, effectively directing water runoff and preventing it from seeping into the building's structure. By creating an overhang, the cornice offers protection against rain and snow, which helps to safeguard the underlying wall materials from moisture damage.

Additionally, although many cornices have an aesthetic function, their primary job is to enhance the functionality of the roof in terms of weather resistance. The proper design and installation of a cornice can significantly contribute to the longevity and durability of a roofing system.

In contrast, while supporting the weight of the roof structure is essential, this function typically falls more to the rafters and trusses rather than the cornice itself. Similarly, insulating the roof against heat loss is a task designated to insulation materials installed within the roof assembly, rather than the cornice design. Enhancing aesthetic appeal is indeed a secondary benefit of cornices, but it's not their primary purpose.