First, calculate the usable area as if for a single tenant floor. Then deduct corridor areas, including toilets, supply room, etc., but do not deduct the enclosing walls of such corridor. Measure the net usable area of each space on the floor by measuring each enclosing wall which is a building exterior wall to the outside surface of the exterior wall, or to the outside surface of the glass as the case may be. Measure demising wall to the center and walls which about corridors to the corridor side of the finished surface of the corridor wall. To determine the usable area on a multiple tenant floor, apportion the corridor area to each space by multiplying the corridor area by a fraction, whose numerator is the net usable area of the space and whose denominator is the total of the net usable areas of all the spaces on the floor, and add the result to the net usable area of the space.
© Stevenson Systems 2016