Fortunately for the unrelated roommates, that is, because in NYC the housing code prohibits more than three to live under the same roof. By one estimate, that would make at least 15,000 units illegal. This article looks at several of them.
NYC is not alone in occupancy codes that are designed to prevent crowding, a measurement of residents per rooms in a dwelling unit (as opposed to density, which is units per acre). However, these laws may be arcane in cities of exceedingly high housing costs that attract young people as well as immigrants of limited income.
"New York, home to some of the nation's highest rents and more than eight million people, many of them single, it is illegal for more than three unrelated people to live in an apartment or a house. The law, for decades part of the city's Housing Maintenance Code, is little known, widely broken and infrequently enforced.
The lax enforcement might not be a bad thing, since a sizable number of the city's denizens. According to the Census Bureau's 2008 American Community Survey, nearly 15,000 dwellings in the city housed three or more roommates who were unrelated to the head of the household. Experts say that number is almost certainly underreported.
Jerilyn Perine, a former city housing commissioner and the executive director of the nonprofit Citizens Housing and Planning Council, said occupancy laws should be determined not by whether people were related, but by whether a unit was safely inhabited, whether by four people or more."
FULL STORY: In New York, Breaking a Law on Roommates

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