Generally horizontal, supporting structure and constituting the bottom level of each story in a building. (ASTM E631-93a)
DISCUSSION?In the case of a sloped floor measure the floor area in the horizontal plane as depicted on a floor plan. Stair landings do not count as floor area, but as part of the stair.
A Unified Approach for Measuring Office Space | For Use in Facility and Property Management : Copyright 2007. Building Owners and Managers Association International and International Facility Management Association. All rights reserved. ISBN # 1-883176-73-5