A method of both permanently reinforcing and bonding, by means of a physical connection including a fabric or other arrangement of reinforcing fiber, saturated with a curing liquid resin, and building materials to create a composite assembly is disclosed. Once cured, the previously liquid resin, having surrounded the fiber and features of the surfaces of the elements being joined, combines them within a single, shared resin matrix. The resulting composite assembly incorporates a new method of providing reinforcement from within, and can be formed into any of various products or components in the light construction industry, such as window sashes, millwork, and the like.