Common spaces are defined in New Hampshire as "all portions of the condominimum other than the units." This includes common hallways, lobbies, elevators, stairways, and any other areas that are shared by all unit owners.
Common spaces are considered to be part of the condominium as a whole, and they cannot be sold or transferred separately from the units. This is because the common spaces are necessary for the use and enjoyment of the units, and their sale would diminish the value of the condominium as a whole.