California State University, Fullerton, paid $30.5 million to purchase the two buildings in the Banting Corporate Center in Irvine, where it has kept a branch campus since early 2011.

The university currently operates out of 3 Banting, while the other building is leased to commercial tenants. It said it plans to occupy both buildings on the site once leases expire, one in 2014 and the second in 2019. The expansion will add 12.35 acres to the university’s overall campus space, including its main grounds in Fullerton.

Cal State Fullerton has operated a separate campus to serve students living or working in Central and South OC since 1989, initially at the Saddleback College campus in Mission Viejo. It moved the campus to the El Toro Marine Corps Air Station in 2002 and later moved it to the Banting Corporate Center.

Cal State Fullerton financed the buy with systemwide bonds. The school said it expects to pay off the debt with rental income from tenants in the new buildings.

“This investment in our Irvine campus reconfirms our commitment to South Orange County,” Cal State Fullerton President Mildred García said in a statement.

The Irvine campus is set to start offering lower-division courses this fall that will take freshmen and sophomores for the first time.