Downtown Ann Arbor office space that sat vacant for years is currently undergoing a major transformation for its new tenant: Barracuda Networks.

The three-story building at 317 Maynard St. — which is attached to the former downtown Borders bookstore — is being converted into high-tech office space for the Campbell, Calif.-based network security firm.

Barracuda, currently at 201 Depot St. in Ann Arbor, signed a lease for the 45,000 square feet of office space in June.

The company hopes to move its 200 workers from Depot Street to Maynard Street by November, said Barracuda Network’s Kelli Jett.

“It’s coming along pretty quickly, so I think we’re on schedule, but early November should be the time frame,” she said.

In order to bring more light into the building, landlord First Martin Corporation knocked out a portion of the wall along Maynard Street and plans to install windows.

"We probably have two weeks to go wrapping up the new exterior windows and we're currently working on ceilings and drywall," said First Martin property manager John Teeter. "We're also working on data writing and building out their server room."

Jett said hiring at Barracuda isn’t slowing down — the company has been hiring people on a weekly basis.

Since June, Barracuda has increased its Ann Arbor workforce by about 20 people.

Barracuda’s Sean Heiney told AnnArbor.com in June the new office space on Maynard Street could eventually house 300 to 400 employees.

“We’re mainly hiring between the Ann Arbor and the Campbell offices,” Jett said. “Our company is building out in every aspect. We’re just growing so quickly I don’t think we can even forecast.”

Barracuda is a privately owned firm that creates network security devices, provides email and Web filtering products and phone system solutions, and monitors network attacks 24 hours a day, 7 days a week from its Ann Arbor office. Fueled by growth in the information technology security industry, it has grown to more than 1,000 employees globally. The company does not report sales figures.

Lizzy Alfs is a business reporter for AnnArbor.com. Reach her at 734-623-2584 or email her at lizzyalfs@annarbor.com. Follow her on Twitter at http://twitter.com/lizzyalfs.