Housing Unit

A housing unit is one of a house, apartment, mobile home, group of rooms or single room that is occupied or intended as separate living quarters. The separate living quarters that define a housing unit are those where the occupants live and eat separately from other residents in the structure or building, and have direct access from the building's exterior or through a common hallway.

The U.S. Census Bureau may consider your residence to have multiple housing units if more than one family occupies it. For example, if you occupy the main floor of a dwelling and your sister and her children occupy the basement, the census would consider your house as having two housing units.

According to the 2010 U.S. Census, there were 131.7 million housing units in the nation, of which 25.9 percent were in multi-unit structures. The annual housing unit estimate from 2016 increased that number to a total of 135.7 million units. More than 10 percent of that estimate is for the 14 million units in California.

The following are generally excluded types of living quarters for purposes of counting housing units:

• Dormitories, bunkhouses, barracks
• Transient hotels and motels (except for those people who consider it their place of residence)
• Quarters in institutions, general hospitals, and military installations (except those occupied by staff members or resident employees)

Each year, the Census Bureau provides housing unit estimates for all states and counties. These estimates are used as controls to the tracking of population growth/loss for cities and towns.

The estimates start with the most recent 2010 census data, and then add in the estimated amount of new residential construction and mobile homes. Next, the estimated housing units lost is subtracted and results in the annual estimate figure.

Residential construction is the largest component of change in housing units. It is made up of both permitted construction and non-permitted construction. More than 98 percent of all new housing units are built in places that issue building permits, according to the Census Bureau.

There are three types of situations that determine the loss of a housing unit. It can either be due to an interior exposed to the elements, a demolished unit, or a home (house or mobile) that was moved. For example, the loss rate of homes, apartments, or flats built between 1940 and 1949 as measured in 2016 was 0.38 percent. Meanwhile, mobile homes had a reported loss rate of 1.76 percent, according to the same 2016 data.