The term BUILDING PART can refer to several components of a building, such as the WING, ELL, ROOF, EAVE, and STORY. The WING is a part of a building that projects out from the main structure, usually at an angle. An ELL is a WING or extension of a building that forms a right angle with the main structure. The ROOF is the uppermost part of a building, typically made of sloping pieces of material such as tiles or metal sheets. An EAVE is the edge of a ROOF that projects beyond the side of a building. A STORY is a level of a building, typically one of several floors.