CHICAGO—Clayco, a development and construction firm based in St. Louis, has confirmed that it will officially move its headquarters here.

The company will expand into the 14th and 27th floors at the Jewelers Building at 35 E. Wacker. Clayco already has an office in the building, about 30,000 sq. ft., after moving from the company’s suburban offices in Oakbrook Terrace in 2010. This move will expand that downtown office to a reported 70,000 sq. ft., and will include principals from each business unit and a subsidiary design firm, Forum Studio. CEO Bob Clark moved his office here in 2010.

Clayco will keep its accounting and information technology workers at the St. Louis office at 2199 Innerbelt Business Center Dr., where the firm recently signed a 15-year lease.

Clark said keeping the St. Louis office will allow the firm to make the move without layoffs, and the company is not receiving any incentives in the HQ transfer. “Clayco is embarking on an exciting period in our company’s history,” he said in a statement. “With a record backlog of projects, and increasing travel around the country and the globe, we see Chicago as an integral part of our expansion strategy as we add talent and build Clayco into the nation’s leading full-service real estate development, architecture, engineering and construction firm.”

Clayco clients include commercial, institutional and industrial projects, including corporate giants like Dow Chemical Co., Amazon, Caterpillar, Procter and Gamble, 3M, and Chevron along with government buildings, manufacturing spaces, healthcare and learning environments, among others. Locally, University of Illinois, Kraft Foods and Blue Cross Blue Shield are among the company’s clients.