They might have tried this in Washington last night, if it weren't so cold.
An unusual method of coining dollars from the waste space on the roof of a building is shown in this view of the U. S. Grant Hotel in San Diego, where about twenty tents have been pitched far above the city. The view is fine, the air good, and as the elevator and other hotel service is at hand, the guests enjoy camp life and city advantages together. The proprietor receives a good rate for these quarters, so that the novel idea is beneficial all around.
Not exactly legal today unless there are good fire exits, but the idea is sound: we waste far too much space on our roofs. They should be gardens, play areas, farms, anything but black tar. From Modern Mechanix
More on roofs for people:
Green Roofs Meet the Ground in New Heden
Roofs are for People