You can determine a building's age by checking to see if there's a date on the meter reader, inspecting the toilet for a date or checking for a listing with a local historic real estate agency or service. Census records can also indicate when the building was constructed.
An architectural investigator can inspect the building's paint, plaster and mortar to determine its age. Thermal-paned windows that have aluminum spacers might have the year they were built, which can be an indication of when they were installed in the property.
Additional building features that can determine age include wiring, nails, flooring, electrical receptacles and structural panels. Aluminum wiring was in use from the late 1960s to the mid-1970s, until it was revealed that the material was a potential fire hazard. Some of the first electrical receptacles had two equal-sized slots and no ground slot, while contemporary receptacles have a rounded hole beneath the vertical slots.
It is also possible to determine building age by architectural style. American Colonial architecture was most popular from the 1600s to the 1800s, while Victorian architecture was prevalent from 1849 to 1900. Economical and compact residences are indications of buildings constructed during the early 20th century, while more minimally designed residences were popular after World War II.