U.S. Gypsum Co. said yesterday that its Southeast Baltimore plant has completed an expansion that added 35 jobs and 90,000 square feet to the 40-year-old facility.

With the addition of a new manufacturing line, the plant is now one of four in the country that makes Durock, U.S. Gypsum's brand of cement boards, which are laid beneath ceramic tiles and have other exterior uses, the company said. The other plants are in Detroit, New Orleans and Sante Fe Springs, Calif.

The Quarantine Road plant, which now stands at around 300,000 square feet and employs 275 people, also makes Sheetrock, a brand of gypsum wallboard, and plaster products. U.S. Gypsum is the No. 1 maker of gypsum wallboard in the world.

"Basically, the East Coast is a growing market for us, and Baltimore is a central location," said spokesman John Mandel. With its Durock and Sheetrock lines, U.S. Gypsum has benefited from the boom in home sales and remodeling projects.

U.S. Gypsum's parent company - Chicago-based USG Corp. - filed for reorganization under Chapter 11 of the U.S. Bankruptcy Code in June 2001, because, it said, of costly asbestos-related litigation.

USG, which earned $16 million on sales of $3.3 billion last year, has not set a time frame for emerging from bankruptcy.

Mandel said the Baltimore expansion didn't require court approval because it was considered a necessary part of the business.

He declined to divulge the expansion's costs.

The plant's manager, Charlie Colman, said U.S. Gypsum added the line at the plant because it had more demand for Durock than it could satisfy with production at the other three plants. The company has 47 plants in the United States.

Running at full capacity, the Baltimore plant could make 90 million square feet of Durock per year, making it the largest producer among U.S. Gypsum's Durock-producing plants, Colman said.

If demand continues to rise, Colman said, the company could hire as many as 22 additional people.