Generally a unit is considered vacant if no persons were living in it at the time of enumeration. However, units temporarily occupied by persons having a usual place of residence elsewhere are classified as vacant; whereas units where the usual residents were only temporarily absent are not classified as vacant.

Newly constructed vacant units are included in the housing inventory if all exterior doors and windows and final usable floors were in place. Vacant units under construction, units being used for nonresidential purposes, units unfit for human habitation, condemned, or scheduled for demolition, and vacant trailers excluded from the housing inventory.