Abstract: A structural component for use in constructing a basement wall has two confronting panels of thermoplastic material joined together to form a closed chamber filled with a rigid structural foam. The width of the chamber is spanned by a plurality of indentations formed in the confronting panels and which are fused to one another to inhibit movement of the panels toward and away from one another. At the opposite sides of the component are joint-forming members which react with similar members of an adjacent component to secure the adjacent components to one another to form an upright wall section.