During last week’s International Builders’ Show in Orlando, David Crowe, chief economist for the National Association of Home Builders, pointed to one demographic that could give the housing market a much-needed boost in the coming years.

Did you immediately think ‘baby boomers’? Think again.

Joined by Freddie Mac Chief Economist Frank Nothaft and David Berson, chief economist with mortgage insurer PMI Group, Crowe expressed measured optimism for the year to come, and one source of momentum might just be living in your basement.

From Robbie Whelan’s story for the Wall Street Journal:

“Of course, as we know, the real savior of housing is demographics,” Mr. Crowe said, citing a pent-up demand for 2 million homes by households that are doubled-up or waiting to buy a home, according to NAHB estimates. Those potential homebuyers or renters “are in mom’s basement, and let me tell you, that’s not a sustainable lifestyle, not for mom, and not for them.

“…He cited numbers showing that between 2007 and 2011, the number of households that are “doubled up,” or have grown children or other potential household heads living with their relatives in the same house, grew from 20 million to 22 million. About 6 million of these housemates are young adults aged 25-34 living with their parents.

“They don’t want to live with you. You don’t really want them living with you,” Mr. Berson told the mostly middle aged and older audience. “They will move out as fast as they can. Unless you make it easy for them [to stay]. Don’t make it easy for them. Help your other home builders kick them out.”

According to Whelan, several workshops at IBS focused on “right-sizing” houses, or creating modest-sized, environmentally friendly homes that appeal to Gen-Y’s sensibilities.

Have you recent built for new homeowners that previously lived with their parents?