advanced structural components comprising a foamed thermoplastic that can be used in virtually any application where wooden components have a use . such structural components can comprise sized lumber , shaped trim , posts , beams or shaped structural members . an advanced profile composite structural component comprising an exterior capping layer with an interior comprising a foamed thermoplastic can be used in the assembly of fenestration units adapted to residential and commercial structures . preferably the profile structural component can be used in a window or door assembly . the profile member is adapted for ease of construction of the fenestration units , can be easily installed in a rough opening to framing members , and can be trimmed and adjusted on site . the profile is structurally strong , thermally stable , shrink resistant and will accept and retain the insertion of fasteners such as staples , nails and screws permanently with substantial retention and little or no damage to the units . the profile structural components possess strength that permits the manufacture of a structurally sound fenestration unit from two or more foamed profile members or other conventional members .