USABLE AREA, SINGLE TENANT FLOORS:
Measure the floor to the outside surface of the building. Subtract from this area the following, including the finished enclosing walls:
• Public elevator shafts and elevator machines and their enclosing walls.
• Public stairs and their enclosing walls.
• Heating, ventilating, and air-conditioning facilities (including pipes, ducts and shafts) and their enclosing walls, unless such equipment, mechanical room space, or shafts serve the floor in question.
• Fire towers and fire tower courts and their enclosing walls.
• Main telephone equipment rooms and main electric switchgear rooms, except that telephone equipment and electric switchgear rooms serving the floor exclusively shall not be subtracted.
This section is much clearer. It begins by stating the building is to be measured to the finished exterior surface of the building which is a variation of the BOMA standard. This can be a difficult task as the building can change thicknesses every floor and there is no way to accurately measure the wall thickness when you cannot access a door opening.
An example of how this can affect the square footage is to look at building with an exterior footprint that is 200 feet by 100 feet. Let us say this building is ten (10) stories with an exterior wall thickness of 7”. The Gross Floor Area (GFA) is 20,000 square feet to the exterior surface, while the interior GFA is 19,651 square feet if measured to the inside of the exterior wall. This can mean additional profits by having the tenants pay for the thickness of the walls.
The next section talks about all the building elements which must be taken out of the total square footage. If a single tenant takes the whole 20,000 square foot floor, they will not be paying for the whole space or GFA. The first two (2) bullets explain that elevator shafts, elevator machine rooms, public stairwells, and their enclosing walls (full wall thickness) are to be excluded. These can all be summed up as Floor Penetrations. Any and all floor penetrating elements are to be excluded from the floor rentable area. So if the 20,000 square foot floor has 2000 square feet of shafts and stairs, the rentable area is going to be 18,000 square feet.
Heating, ventilating, and air-conditioning elements (pipes, ducts, shafts) and their enclosing walls (full wall thickness) are also considered floor penetrating elements. If a buildings boiler and air handling unit are in the basement, there are shafts that need to run up to the top floors without interruption. This means each floor will be penetrated by the shaft and need to be taken out of their rentable square footage. The times when this may not happen is in specialty spaces where there may be an excessive amount of computer hardware in which the tenant installs their own air handling unit on their floor to cool the computers. This is a situation where it only serves this one tenant and is not excluded from the total square footage.
The same goes for all fire tower, fire tower courts, and their enclosing walls. Fire towers are defined in New York as an exit that can be used in lieu of an interior stairwell as long as they comply with all requirements for an interior stairwell, with a few modifications, e.g., walls must have a fire resistance rating of at least four (4) hours, be accessible only through an outdoor balcony or fireproof vestibule, open directly to the street or court yard, etc. A Fire Court is the space in which the fire tower exits into and must be open to the sky.
Lastly, all main telephone, electric, other mechanical spaces, and their enclosing walls are not to be counted unless they specifically serve that floor in the same respect as the heating, ventilating, and air-conditioning units.