The structural core of a building's inner framework is topped out when it reaches its maximum height. This is often lower than the building's own architectural height, and may occur weeks or months before the building itself is topped out.

Structural cores are commonly used in skyscrapers which employ a mixed material framework. Typically the core itself consists of reinforced concrete shear walls, while the frame around it may be steel (forming a tandem construction), or composite steel and concrete beams.

The endpoint concerns the core itself. The surrounding frame can still be incomplete, so core topping out does not necessarily establish framework completion or the building's maximum architectural height.