Louisiana-Pacific, the Portland, Oregon-based building materials manufacturer, and two of its plant managers have pleaded innocent to felony charges leveled by a federal grand jury in Denver. The indictment charges the company and two managers at the company's Montrose, Colo., Inner-Seal plant with conspiring in a "scheme to defraud" purchasers of oriented strand board (OSB) produced at the plant between 1989 and 1994. According to the grand jury, the Montrose mill managers deliberately deceived industry quality auditors and misled customers about the quality of the OSB the plant produced. An issue of trust. Although some builders avoid OSB in favor of the more expensive plywood, most have come to accept it for at least some sheathing applications. OSB's wide acceptance since its introduction in the mid-1980s is due, in part,