How is the rentable area of a floor calculated?

The rentable area of a floor is calculated by measuring from the inside finished surface of the dominant portion of the permanent outer building walls. This method provides a standardized approach to determining the area that can be leased and is critical for establishing rental rates.

This calculation focuses on the usable space within the walls, allowing tenants to understand what space they actually occupy without including the thickness of the walls themselves, which are not livable or usable. This approach ensures that tenants are charged for the space they can actively use, creating a clear and fair basis for determining rental costs.

The other options do not define the rentable area accurately based on industry standards. Measuring from the exterior walls would include wall thickness, measuring all unutilized spaces within the building would not adhere to the concept of rentable area, and excluding staircases and elevators would not reflect typical measurements as these areas can impact the total rentable space depending on the property's design and use.