Developers will be required to build more affordable housing in new projects in Cambridge, starting June 30.

The Cambridge City Council voted at its meeting on Monday, April 3, to increase the amount of affordable housing developers are required to make from 15 percent to 20 percent of the total number of units in a project. The amended zoning requirements will apply to any permits issued after June 30. Developers who received permits before then will still be required to meet the previous 15 percent affordable housing requirement. The new affordable housing requirement applies to any building with 10 or more housing units.

Rents for affordable housing units created through this program are set so that tenants pay no more than 30 percent of their income for rent and utilities.�Developers of projects with inclusionary units may be eligible for a density bonus that boosts the building's floor area and total number of units up to 30 percent over what's allowed by the zoning district the project is in.

Mayor Denise Simmons thanked the citizens and housing advocates for their support and said to have socioeconomic diversity in Cambridge, the council must be �intentional� in its efforts.

�It will not happen on its own,� Simmons said. �And we have taken bold and important steps and this is only one.�

The mayor said the council has already taken some extraordinary steps, such as taking property by eminent domain, looking at legalizing Airbnb, and looking at the city�s condo conversion practices.

�This is not one and done,� Simmons said. �There�s so much work that is yet to happen in order for us to keep Cambridge diverse and affordable, but this is clearly an important step.�

Councilor Nadeem Mazen said he was proud of the work of the council. The issue was in his �hopes and dreams bucket since 2013,� although he said there is still work left to be done.

�Twenty percent affordable, inclusionary housing is not going to solve the city�s affordable housing crisis,� Mazen said.

Councilor Leland Cheung said while the amendment will have �monumental impact," it is also �one step in a series of many steps that the council is taking and will take to try and address housing."

�We�re in the midst of a housing crisis when you have graduates from MIT testify that they�re going to apply for affordable housing,� Cheung said. �Something is broken in the city and we clearly need to do more, and I think this council has shown more courage and more determination to do more than anyone expected of it.�

Vice Mayor Marc McGovern called the increase to 20 percent �the most monumental thing this particular council has done in our two years, and probably that the council has done in a long time.�

McGovern said the change will create �hundreds upon hundreds of new units for people� and almost double the amount of affordable housing that developers have to provide �at their dime, not ours."

�Hundreds of millions of dollars is going to come in new affordable housing to Cambridge at no cost to taxpayers or the city,� McGovern said.

�This is going to be one of those things that we�re going to look back after our time here is done and say �I did something good,�� McGovern added.