Interstory

Interstory, or interstory height, is the vertical distance between the finished floors of two adjacent stories in a building. It is measured from the finished surface of one floor to the finished surface of the next, and includes structural slabs, ceiling assemblies, and any dropped or raised ceiling space. It is distinct from clear height, the unobstructed vertical dimension inside a space, and from floor-to-ceiling height, which is the distance within a single story.

Interstory height is determined by architectural design, structural systems, and applicable codes, and varies by building type and region. Typical ranges are that residential buildings use about 2.4 to 3.0 meters (roughly 8 to 10 feet) between floors, while office buildings commonly use 3.0 to 4.0 meters (approximately 10 to 13 feet) to accommodate mechanical services and lighting. Some projects, such as industrial, retail, or high-end spaces, may adopt higher or lower heights depending on function, aesthetics, or retrofit constraints.

Implications of interstory height include effects on total building height and construction cost, as well as daylight penetration, acoustics, and vertical scale. Larger interstory heights can improve daylighting and views but increase structural demands, fire-safety considerations, and service runs for stairs, elevators, and mechanical systems. Smaller heights can reduce costs but may constrain capacity for utilities and limit occupant comfort.