Oftentimes there is confusion regarding how to label floors so this week we are taking some time to remind our extended family and friends how to label floors.
The key to properly labeling levels on plans is appropriately setting the grade datum. This datum establishes the label for the first level of the building from which all other labels are derived.
The first level FULLY above or completely on the grade datum is the “first floor.” The floor directly below is either a basement or a cellar. If the level is MORE THAN 50% below grade datum, it is a cellar. If it is LESS THAN 50% below grade datum, then it is a basement. Keep in mind that the distinction between cellars and basements is very important both from a code and zoning perspective, however because of the different definitions in these different sets of rules, it is possible to have a level that is both a basement and cellar simultaneously.
If the first floor below the datum is a “basement”, the floor directly below is a “cellar.” Each story below a cellar is labeled a “sub-cellar”. If there is more than one sub-cellar, they are labeled as “sub-cellar 1”, “sub-cellar 2”, and so forth with “sub-cellar 1” being the level immediately below the cellar.
Floors above the “first floor” follow standard numerical order, the only exceptions being “penthouse,” “bulkhead,” or “mezzanine,” which must follow very specific rules within the Building Code to qualify. A mezzanine is labeled based on the floor to which it is above or open to. For example, a mezzanine located between the 3rd and 4th floor levels that is open to the 3rd floor should be labeled “Mezzanine 3.”
The floor labeling is ALWAYS based on the Building Code definitions. If the labeling conflicts with zoning definitions, the zoning drawings should provide double labels making it clear that a given level may have different names. For example, information could be provided as: “Basement Plan (Cellar Plan – Zoning).”
If “marketing” floor labeling is proposed, drawings should always be labeled in accordance with Building Code definitions in accordance with the above standards, with marketing floor labels indicated separately. For example, information could be provided as: “13th Floor Plan (14th Floor Plan – Marketing).”
The FDNY also has some rules regarding marketing floor labels which can be found here.