Renovating existing apartments could go a long way toward reducing a statewide shortage of affordable rental units, the executive director of the Housing Alliance of Pennsylvania said Thursday.

"We don't have to build new," said Elizabeth Hersh. "The housing stock is out there."

She was the main speaker at a community forum that drew 80 representatives from housing authorities, consumer organizations, tenant groups, banks and legislators' offices.

The Housing Alliance, based in Glenside, Montgomery County, is a consortium of more than 500 organizations and individuals working on affordable housing efforts.

The event, which drew people from as far away as Somerset and Erie counties, was held at the Regional Learning Alliance in Cranberry.

Allegheny County could use another 21,500 units for its lowest-income renters, Ms. Hersh said. That number represents almost 10 percent of the 220,000 additional apartments needed across the state.

About 43 percent of the state's apartment units were built before 1950, and many are in need of upgrades, she said. Fully 60 percent of apartment owners are "mom-and-pop" operators who rent just one to four units.

More state and federal encouragement is needed to assist landlords who are willing to contribute their own labor to renovation efforts that would make more units available to lower-income tenants, she said.

Each government dollar spent on rehabilitation and remodeling of existing housing returns as much as $2.28 in increased economic activity, Ms. Hersh said. That statistic comes from a survey by Philadelphia-based Econsult Corp.

Southwestern Pennsylvania needs a "balanced" housing market that includes subsidized apartments and home ownership assistance for low-income families, as well as traditional owner-occupied homes and apartments that rent at market prices, she said.

The forum also offered an opportunity for groups involved with affordable housing to exchange ideas and network.

Tight state and local government budgets mean social service agencies have to collaborate and share information on their best practices, Craig Burkley said. A member of the Housing Alliance's board, he is chief operating officer of NeighborWorks Western Pennsylvania.

The local office, located Downtown, is part of NeighborWorks America, a nonprofit organization created by Congress to provide financial support and technical help for community revitalization efforts.

"We have to get people talking and avoid duplication of services," Mr. Burkley said. "An organization planning a new program always should be aware that another agency five miles down the road already is performing that service."

After hearing introductory remarks, forum participants divided into smaller groups to discuss ideas for inclusion into an action plan.

Information and proposals gathered at the Cranberry session will be combined with comments from similar forums being held around the state, Housing Alliance board member Ellen Kight said. She is president of the Pittsburgh Partnership for Neighborhood Development.

The preliminary results will be unveiled Nov. 10 during the annual "Homes Within Reach" conference at the Hilton Harrisburg. A final report will be released in spring 2011.

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