A crown molding and system for its use where the crown molding is formed from a specially blended plastic as extrusions to have a roughened surface and consisting of an inverted "L" bracket and a facing crown mold member for each crown molding section. The inverted "L" bracket is formed as a right angle section having right angle legs and is to be attached to a wall at points along its lower leg, with the right angle bend fitting into the wall to ceiling junction, and with the top leg end having a coupling end for connecting to a mount of a facing crown molding member. Which coupling edges are preferably mirror image corrugations that fit over and lock together, and with the facing member ends flanges to contact the wall and ceiling surfaces.