The cover of any building, including the roofing (see
   Roofing) and all the materials and construction necessary to carry and
   maintain the same upon the walls or other uprights. In the case of a
   building with vaulted ceilings protected by an outer roof, some writers
   call the vault the roof, and the outer protection the roof mask. It is
   better, however, to consider the vault as the ceiling only, in cases
   where it has farther covering.