The anatomy of the average American home, be it owned or rented, hasn't changed much in recent years, considering only 12 percent of the nation’s 112 million occupied housing units were built after the year 2000.

But data released by the U.S. Census Bureau this morning from the American Community Survey (ACS) does offer some insight into how the average Joe lives, and what new home builders are competing against in the resale landscape, which currently includes nearly 4.7 million units of existing inventory–an 11.2 month supply.

Currently, more than 69 percent of U.S. households reside in single-family homes, the Census reports, compared with 24.6 percent in attached units, and 6.3 percent in mobile homes or other structures.  Slightly more than two-thirds (67.2 percent) of homes are owner-occupied, whereas 32.8 percent are rental units.

Big houses may have constituted the bread and butter of the housing boom, but they are not the norm in the bigger picture. In fact, the majority of U.S. residences (70.3 percent) contain just four to seven rooms, with a median overall room count of 5.5. Fewer than one in five housing units (17.4 percent) feature eight or more rooms.

Some 67.3 percent of housing units contain two or three bedrooms. The number of housing units outfitted with four or more bedrooms stands at 20.8 percent.

Roughly one-third (33.1 percent) of households have one car, whereas a slightly larger share (38.1 percent) have two cars.  Only one in five households has three or more cars.

The average owner-occupied residence is home to 2.7 people (for rentals, that number is slightly lower, at 2.42).  Only 33.9 percent of U.S. households now include children under 18–a reflection, no doubt, of an aging population with a larger percentage of Americans now entering retirement age.

Jenny Sullivan is senior editor, design, at BUILDER magazine.