What is a dormer?

A dormer is specifically defined as an opening in a sloping roof that typically includes a window. This architectural feature allows for increased natural light and ventilation in areas of the building that are otherwise difficult to illuminate, such as attics or upper floor spaces. Dormers can enhance the aesthetic appeal of a structure and provide additional usable space, making them a common choice in residential design.

In contrast, while roofing materials, structural components, and insulation methods are important in the context of roofing and construction, they do not accurately define what a dormer is. Roofing materials pertain to the various substances used to cover and protect the roof. Structural parts refer to the elements that support the roof's framework, and insulation methods are related to how heat retention is managed within the roof assembly. Hence, the choice that identifies a dormer as an opening in a sloping roof for windows provides the most accurate description.