Developers who want to build above existing height allowances in Seattle neighborhoods will now have to offer some of the increased space at an affordable rent.

The change occurs after the Seattle City Council approved both a resolution and an ordinance to apply incentive zoning to neighborhoods at a Planning, Land Use and Neighborhoods Committee meeting on Dec. 10.

The Workforce Housing Incentive Program is designed to encourage a wide range of affordable housing in the city. If any rezoning occurs to increase building height in Seattle's neighborhoods, it requires that developers offer 15 to 17.5 percent of the increased space at rent that is affordable for members of the city's "workforce."

As an alternative developers can pay $18.94 per square foot of increased floor space to provide affordable housing elsewhere.

The Workforce Housing Incentive Program has been in place in Downtown Seattle since 2006. Instead of providing for residents with very low income, like some other housing programs, incentive zoning targets those who earn up to 80 percent of the area's median income. In Seattle that is an annual salary of $43,000.

One major difference between the 2006 rezoning in Downtown Seattle and the new legislation for neighborhoods is that the proposal does not effectively rezone any Seattle neighborhoods. Instead, it requires that developers help create affordable housing in the event that any rezoning occurs in the future.

Chair of the land use committee Sally Clark has said that as neighborhoods become more dense, she aims to provide more affordable housing in exchange.

"When we do major upzones in neighborhoods the developer should share in making the neighborhood more affordable," said Clark.

Anna Markee, outreach director of the Housing Development Consortium of Seattle-King County said that for years the Consortium has supported incentive zoning as a tool to create affordable housing.

"We're really excited that there will be more housing opportunities for working families in our neighborhoods," said Markee.

Mayor Greg Nickels' office released the following statement: "This is another important step to make sure that our teachers, bus drivers, grocery clerks and hotel workers are able to both live and work in Seattle."

Still, some are less enthusiastic about the legislation. The Seattle Displacement Coalition has publicly opposed the proposal. John Fox, the organization's coordinator, says that the city should require developers to provide more affordable housing and at a much lower rent.

"They've passed a proposition that does not achieve very much at all," says Fox. "It's going to be easier for developers to get very lucrative upzones."

When voting on the proposal the council also decided to allow incentive zoning to operate with a Multifamily Tax Exemption Program, which benefits property owners who price a portion of their units at moderate rates.