Chattanooga-based EMJ Corp., one of the nation's top construction companies, has a new chief executive as Jay Jolley takes the day-to-day controls of the business.

Mr. Jolley, 49, moves up to CEO from president of the company.

Jim Sattler, who was EMJ's chief executive officer for the past 18 years, steps aside as CEO but remains as chairman.

Chief Operating Officer Burt Odom keeps that job and assumes the president's slot, according to the officials.

Mr. Sattler, 66, said the two colleagues have been groomed for their new positions for several years at the construction company.

"Going forward we're positioned very well," he said.

Mr. Jolley, whose father Edgar M. Jolley started the business in 1968, said the shifts are a finalizing of a process under way for several years.

"I've been proud to have Jim as a mentor," Mr. Jolley said. "I fully expect to have a smooth transition."

The moves come as EMJ has taken steps to diversify its operations. For many years it was associated with the retail sector and with locally headquartered shopping center developer CBL & Associates Properties Inc.

Mr. Sattler said retail is about 30 percent of its business now.

Mr. Jolley said diversification is taking a variety of forms relating to not just kinds of projects but size, client type and publicly and privately funded work.

In addition, EMJ has started or acquired new businesses.

For example, earlier this year EMJ bought Inman Construction in Memphis. The move was aimed at expanding into medical, university and public school construction as those sectors are poised for growth, Mr. Jolley said.

Meanwhile, in 2009 EMJ started Core Safety Group and Accent Construction Management. Core offers safety consulting services, while Accent helps contractors with project development and financing.

Mr. Jolley said EMJ officials want to even out the economic ups and downs which take place.

"As the economy moves up and down, at EMJ we're solid and steady and able to absorb them," he said. "We're excited about the future of EMJ Corp."

Still, Mr. Jolley said the construction business remains in recovery mode from the severe recession.

Mr. Sattler said company revenues fell from about $1 billion in 2007 to some $500 million in 2009.

"Construction is off throughout the U.S.," he said.

EMJ officials said they'll continue to seek business nationally and locally. EMJ recently finished building the Majestic movie theater downtown.