CertainTeed Corp., a Valley Forge, Pa.-based building materials manufacturer, opened a 518,000-sq.-ft., state-of-the-art mechanical insulation manufacturing plant in Sherman, Texas. The plant will produce ToughGard2®, a textile fiberglass duct liner used to insulate heating and air conditioning duct systems. The company has committed a $15 million capital investment in the facility, which will employ up to 50 people when fully operational. The company formerly used a textile duct liner produced by a third party until an explosion in February 2003 destroyed that plant.