Two sizable south Napa commercial buildings sold to a Bay Area real estate investment company for $21.13 million.

A two-building, 77,203-square-foot complex called Carneros Commons sold to Black Mountain Properties, LLC, and Black Mountain Holdings, LLC, on March 29, according to the buyer and public records. The seller was Lafayette-based Carneros I, LLC, which purchased it in March 2007.

The buildings, located at 2700 Napa Valley Corporate Drive and 851 Napa Valley Corporate Way, are designed to be “office-flex,” which means they accommodate office or light-industrial uses.

"We were attracted to the investment's quality rent roll and immaculate buildings,” said Tony Bullock, president of Black Mountain Properties, in a statement. “The acquisition became obvious to us after digging into what the future holds for the greater Napa Valley Commons development.”

A big addition to the business parks around Napa County Airport is the redevelopment of the 154-acre Napa Pipe property with retail and commercial space and 945 homes. After years of environmental remediation, construction started in earnest late last year. The lead tenant there, Costco Wholesale, is set to open next year.

Founded in 1937, Black Mountain Properties ( owns more than a dozen buildings in about a half-dozen cities in the East Bay and South Bay of the San Francisco area.

Scott Bertrand, Derik Benson and Tim Howarth of Cushman & Wakefield represented Black Mountain in the sale. The seller represented itself.