Disclosed are a series of composite polymer composite structures formed by the coextrusion of at least two distinct polymeric compositions including a structural composition and a coating composition whereby the primary structural frame formed from the structural composition includes at least one, and typically a plurality, of longitudinal recesses or cavities. These recesses or cavities may, in turn, be filled with a third distinct polymeric composition that may include wood byproducts and/or a foaming or blowing agent.