DETROIT—Rock Ventures, the operational arm of Quicken Loans Chairman Dan Gilbert, said it has purchased the 333,000-sq.-ft One Woodward building in the downtown.

The 26-story building, built in 1962 and designed by Minoru Yamasaki, is on the corner of Jefferson and Woodward avenues. Lehman Brothers Holdings Inc. is the seller. The price was not disclosed.

Rock Ventures plans to renovate the building in order to accommodate the growing demand for space in the city’s emerging technology district. “The One Woodward building is located in the heart of Detroit’s technology core, and provides us more space to further accommodate our growing family of companies and the increasing number of businesses that want to leverage the opportunities made in Detroit,” Gilbert said in a statement. “We continue to bet big on Detroit, and this purchase reinforces our commitment to the exciting entrepreneurial action on Woodward Avenue.”

The building is approximately 60 percent occupied, and will exceed 90 percent occupancy next month when Quicken Loans and its affiliates lease a total of eight floors in the building. Some current tenants include the Detroit Regional Chamber and law firms Fraser Trebilcock Davis & Dunlap, and Kitch Drutchas Wagner Valitutti & Sherbrook. The building was the former headquarters of Michigan Consolidated Gas Co.

Friedman Integrated Real Estate Solutions and Bedrock Real Estate Services LLC, Rock Ventures’ full-service real estate firm and developer for the project, co-brokered the purchase. Bedrock will also be responsible for overseeing the renovations, managing the property and leasing the space.

Since January 2011, Rock Ventures has purchased 10 buildings downtown totaling nearly 2.5 million square feet of office space, in addition to two parking garages with a total of 3,500 parking spaces. Last month, the company broke ground on a 33,000-sq.-ft. specialty retail development with 10-story parking garage in downtown Detroit.