Former Treasury Department assistant secretary Michael Barr wants Fannie Mae and Freddie Mac multifamily programs to receive a government guarantee against catastrophe and also be separated from single-family programs. At the National Multi Housing Council's mid-year apartment strategies conference, Barr said he believes some type of federal backstop for the growing multifamily sector is needed. And growing it is. A new report suggests more than 500 cities are noticing a trend where more homes are becoming rentals. The NMHC is a trade group representing the apartment industry. Barr advocated having a government guarantee for single-family and multifamily housing for catastrophic situations, but not for first-loss positions. The focus on multifamily is tied to the predominant belief that renting will be the future for a larger number of Americans in the wake of the housing crisis. Doug Holtz-Eakin, president of the American Action Forum and director of the Congressional Budget Office, said housing subsidies should not be limited to homes that are purchased, but for rental properties, as well. Yet, he said future financing should emphasize equity over debt financing. Over the next decade, a shift in the rental market is expected. Professionals attending the conference said the vision of neighborhoods will change nationwide, with more apartments built in urban areas for renters who want easy access to entertainment and employment. Write to Kerri Panchuk.