Information about Thirteenth Floor

The levels of a multi-story building are numbered sequentially, from "one" or "ground" upwards. In some countries, the number 13 is considered unlucky and building owners will sometimes purposely omit the thirteenth floor. Even landlords who are not themselves superstitious realize that the rentability of suites on the 13th floor might be compromised because of superstitious tenants, or commercial tenants who fear superstitious customers.

See sequence in OEIS for number series and graphs.

How it is done

Skipped

Most commonly, it is skipped altogether. Although the thirteenth floor has been skipped in terms of numbering (e.g., for hotel/apartment/suite numbers), the floor numbered 14 is technically the thirteenth floor of the building; it is simply not numbered as such. Any calculations involving the height of a building based on the height of a floor should take this into account.

12A

Sometimes the floor is simply renumbered as 12a; this does not affect the numbers of the higher floors.[1]

Special designations

Other buildings will often use names for certain floors to avoid giving a floor on the building the 13th floor designation. One such example is the Radisson Hotel in Winnipeg, Manitoba, where the 13th floor is called the Pool floor.

Uninhabited

Sometimes, the floor is put to some other use (see conspiracy theories, below).

Letter "M"

Because the letter M is the 13th letter in the English alphabet, some people may use a letter "M" as a substitute for the 13th floor, such as 12, M, 14, and so forth. In Richmond, Virginia, the Monroe Tower has a 13th floor, but it is used for mechanical equipment and is only accessible from the freight elevator or the stairs. The "M" designation on the elevator buttons of the freight elevator can also be construed as meaning the "Mechanical" level in this particular building.

Variant

Similarly, new buildings in some parts of China omit the fourth, fourteenth, twenty-fourth, etc. floors, as the word "four" (Hanzi: ) sounds like "death" ( – pronounced "sì" and "sǐ", respectively) in Mandarin, the predominant dialect for the country, and most other Chinese dialects. A small number of buildings also follow the Western tradition of omitting the thirteenth floor, with the fifteenth floor immediately following the twelfth.

Although the Hanja for four and death are read identically in Korean, buildings in South Korea tend not to omit the fourth floor. However, newer buildings tend to label the fourth floor with the letter F, instead of the number 4.

Conspiracy theory

Some conspiracy theorists have suggested that the thirteenth floor in government buildings is not really missing, but actually contains top-secret governmental departments, or more generally that it is proof of something sinister or clandestine going on . This implication is often carried over, implicitly or explicitly, into popular culture; for example, in the films The Thirteenth Floor, the hidden research and development labs of Network 23 in the television program 'Max Headroom', the top-secret research and development division of The Hitchhiker's Guide to the Galaxy in the fifth book of the series, Mostly Harmless, and the computer game Floor 13 by Virgin Interactive. In the sci-fi comedy Red Dwarf "floor 13" referred to a secret brig which was several decks high.

It is widely believed that Canary Wharf's One Canada Square houses a plant room on its level 13 but this is just another example of undeserved notoriety on the part of the 13th floor. One Canada Square's plant areas are in its basements (Levels B3 to M1) and above Level 50 (Level M2). The floor directly above level 12 is level 14.

It should be noted that to place a floor between those accessible from an elevator, it is necessary to either take longer to travel between the neighboring floors, or accelerate, both of which would be noticed by the riders. It would also be noticeable from the exterior, requiring either an extra row of windows or a conspicuous gap between rows. Thus, it would make much more sense to build a secret floor as a basement.

See also

• Mechanical floor
• Triskaidekaphobia