Whether it's to save money, live more simply or simply to champion an artsy style, living in a renovated warehouse is among the top priorities of many people. The big question, though, is whether it's legal. And the short answer is, "it depends."
City planners generally split their cities into different zones, such as residential, commercial, industrial or recreational. Whoever builds within a certain zone must build according to the zone's restrictions. So, you can't build a two-story house with a white picket fence for a family of four in a commercial zone. You must build such a structure in a residential zone. But in some situations, a person might find that a warehouse has nearly everything a person needs to survive comfortably, such as a bathroom, kitchenette and other rooms, and might decide to live there.
People living in warehouse spaces often are artists or urban professionals who require a lot of space to create or sell their work, as was seen during the late 20th century in San Francisco and New York. Since artists there spent so much time working, and often had little money, it was logical to live where they worked. Some lived where they worked, regardless of zoning laws. Noticing this trend, builders began renovating buildings into "live-work" spaces where artists could live comfortably and work efficiently. City officials started to adjust zoning regulations to accommodate the change.
Sometimes building renovations evolve faster than zoning regulations, so a lot of communication between builders and city officials must occur before living in a renovated warehouse becomes truly legal. Some buildings may officially only allow working artists to reside in them, but other urban professionals may end up living in the building, too. It's up to the building owners to ensure that zoning regulations are met.
Even if someone renovates warehouse space into living quarters, if the space isn't zoned for residential use, living there is called "squatting," and it's illegal. This doesn't stop people from doing it, however, and they may get away with it for years before anyone notices. Once city officials do notice, though, the choice is either to jump through the bureaucratic hoops by working with the building owners and the city to get the building zoned properly, or to moving out.