Santa Clara County supervisors have approved a quartet of housing projects that will convert existing properties into more than 300 affordable housing units.

The board unanimously approved the purchase of four properties — two in San Jose, one in Morgan Hill and one in Santa Clara — that will be converted into 324 combined housing units.

Once completed, all four housing complexes will include at least 72 housing units and one unit for on-site management.

One of the properties, located at 21 N. 21st St. in San Jose, will also include roughly 10,200 square feet of commercial space in addition to its 80 housing units, which will be reserved for people with developmental disabilities, youth who are transitioning out of the foster care system, those with Section 8 housing vouchers and homeless residents.

The other three projects will be located at 15440 Monterey Road in Morgan Hill, 3335-3337 Kifer Road in Santa Clara and 1135 E. Santa Clara St. in San Jose.

“These are the type of projects that’s exactly what we need,” Supervisor Otto Lee said during the board’s Tuesday morning meeting.

Primary funding to buy and convert all four properties will come from 2016’s Measure A, a voter-approved $950 million affordable housing bond.

The county has already supported affordable housing projects with Measure A funding in Cupertino, Sunnyvale, Mountain View, Gilroy and Milpitas in addition to Santa Clara, Morgan Hill and San Jose.

Of the 41 Measure A projects the county has approved, 29 of them are in San Jose.

Supervisor Cindy Chavez said Monday that the county also intends to launch affordable housing projects in additional cities across the county.

Chavez said that the county chooses Measure A projects by alerting cities that funding is available.

“It allows any city that wants to have a project in their community (to) come to us,” Chavez said.

Nearly 900 housing units have already been built using Measure A funding, according to the county, with another roughly 2,000 units under construction or scheduled to begin construction in the next six months.

County officials expect to utilize up to roughly $17.1 million in total to buy the four properties.

Construction to convert the four properties into housing units is expected to begin this summer, according to the county.