In a series of posts, NAHB examined key housing statistics from the 2012 American Community Survey (ACS) for metro areas in the United States. One statistic that drew interest was the share of homeowners living in single-family detached housing. This post expands that analysis by looking at the share of total housing units (owned and rented) from 2005 to 2012.
The share of single-family detached housing is calculated by taking the total number of single-family detached units divided by the total number of housing units. The share of single-family detached housing or single-family concentration gives a snapshot of the housing stock for a specified geography.
At the national level the single-family concentration has changed very little in recent years. According to the ACS, in 2012 the concentration was 61.6% compared 61.1% in 2005.
The small movement in the single-family concentration at the national level is not surprising. The U.S housing stock is aging. According to the latest data from the Department of Housing and Urban Development American Housing Survey (AHS), the median age of an owner-occupied home was 35 years in 2011. The median age reported in the 1985 AHS was only 23 years.
Therefore, if the single-family concentration is not effected in large order by removing housing units, changes are instead the result of the growth in new construction of single-family housing relative multifamily housing. For example, an increase in the single-family concentration is the result of more single-family housing being added than multifamily housing. Conversely, a decrease in the single-family concentration is the result of fewer single-family housing being added than multifamily housing.
Although the single-family concentration showed little movement from 2005 to 2012 at the national level, several metro areas did experience noticeable change. Metro areas with the largest percentage point increase in the single-family concentration from 2005 to 2012 are shown below.
One trait shared by the metro areas in the top ten was above average population growth. From 2005 to 2012, all metro areas in the top ten with the exception of Yakima, WA experienced double digit population growth. The population growth in Auburn-Opelika, AL during the time period was over 24%.
Population growth alone cannot explain the large increases in the single-family concentration. Land use regulation and availability also play a role. Higher concentrations are typical of locations with less dense developments.
MSAs with the largest percentage point decrease in the single-family concentration from 2005 to 2012 are shown below.
The metro areas in the bottom ten do not share the trait of average population growth. It is worth keeping in mind that population growth can produce a falling single-family concentration, if the growth results in apartments rather than single-family homes. For example for the list above, Greenville, NC experienced population growth over 25% while Victoria, TX experienced population growth of only 1%. Thus, land use regulation and availability play leading roles. Lower concentrations are typical of locations with denser developments.
Although the national figures saw little movement from 2005 to 2012, certain metro areas saw noticeable movement. These figures allow us to examine the relative growth in single-family and multifamily housing units for each metro area.