“We estimate right now, even with households that have been consolidating, as young adults have been moving back with their families, we still think we are at a deficit of roughly around 900,000 units in the U.S. in terms of what we need just to get back to normal in terms of single-family,” Ivy Zelman, CEO of housing research firm Zelman & Associates, said on a recent webcast from Willy Walker of Walker & Dunlop.