Polymer-based composite structural boards and structural systems

A foundation wall system of a building structure, comprising:

• a concrete foundation wall having an interior side and an exterior side;
• a plurality of polymer-based composite structural boards overlaying and secured to the interior side of the concrete foundation wall and forming an interior sheathing layer of the foundation wall system;
• a plurality of polymer-based composite structural boards overlaying and secured to the exterior side of the concrete foundation wall and forming an exterior sheathing layer of the foundation wall system that is in ground contact;
• each of the polymer-based composite structural boards having a polymer material or predominantly polymer material core layer with a density between 1.6 lbs/ft3 and 25 lbs/ft3;
• the core layer of each of the polymer-based composite structural boards having a length, a width, and a thickness;
• and the core layer of each of the polymer-based composite structural boards having a first major surface and a second major surface that are each defined by the length and the width of the core layer with at least one of the major surfaces being overlaid by a facer that is generally coextensive with and bonded to the overlaid major surface.

A utility conduit section for housing utilities, comprising:

• a utility conduit section having a generally rectangular in transverse cross section with a top wall, sidewalls, and a bottom wall that are constructed from polymer-based composite structural boards;
• each of the polymer-based composite structural boards having a polymer material or predominantly polymer material core layer with a density between 1.6 lbs/ft3 and 25 lbs/ft3;
• the core layer of each of the polymer-based composite structural boards having a length, a width, and a thickness;
• and the core layer of each of the polymer-based composite structural boards having a first major surface and a second major surface that are each defined by the length and the width of the core layer with at least one of the major surfaces being overlaid by a facer that is generally coextensive with and bonded to the overlaid major surface.