TAMPA - When the city council approved massive changes to its zoning code this month, the board also passed a measure that could help more people achieve the dream of home ownership.

Families of four earning as much as $65,280 will benefit from the change.

The zoning code lists several ways developers can earn density bonuses. Developers can choose from a list of options, such as providing affordable housing or creating a park, in exchange for permission to build more units than the zoning allows.

Under the old version of the code, developers that chose to provide affordable units had to make those units affordable to people who earn 80 percent of the area median income, or $43,500 for a family of four.

Under the new code, developers that choose to offer affordable housing must make those units affordable to families of four who earn up to $65,280, or 120 percent of area median income.

Homes generally are considered affordable if people spend no more than 30 percent of their income on housing.

Rising home costs prompted the change.

The median home price in the Tampa Bay area was $230,900 in May, according to the Florida Association of Realtors.

That represents an 18 percent increase over May 2005.

"Because the price is escalating, the people at 80 percent are having an extremely hard time finding affordable housing," said Sharon West, the city's housing manager. "Even people at 100 percent or 120 percent are having a difficult time."

The code change also requires the units to remain affordable for at least 30 years, a measure designed to prevent developers and buyers from flipping cheaper units and selling them for more money, said Cyndy Miller, director of the Business and Housing Development department.

The code, however, does not detail how many more units developers would be able to build if they provided affordable units. A formula is in the works.

Urban planners, however, have started working on a complex formula specifically tailored to the Channel District, a neighborhood experiencing tremendous growth.

For example, if a developer can build a 301,000-square-foot project but wants an additional 43,000 square feet to build more units, the developer would have to set aside 14 units in a lower, more affordable, price range.

The Channel District proposal is scheduled to be considered by the Hillsborough County City-County Planning Commission in August, and the Tampa City Council in October.

Reporter Ellen Gedalius can be reached at egedalius@tampatrib.com or (813) 259-7679.