About GPS Structurally Insulated Panels (SIP) A structurally insulated panel is an engineered wood product that consists of two outer skins, generally made of oriented strand board (OSB), with an inner core of expanded polystyrene. When these components are pressure laminated together using an appropriate adhesive they form a strong structural panel. These panels are bounded by top and bottom plates which are connected to the panel using conventional nails or staples. Global Panel Systems manufactures their structurally insulated panels in 4’x 8’ and 8’x 8’ sizes with varying thickness of expanded polystyrene, generally from 3 ½ “ to 5 ½ “ thick. These panels can then be joined together either by OSB splines or double 2” x 4” or 6” timber stud splines at the joints. Optional electrical chases can be incorporated into the panels to make it easier for electricians to wire the finished structure. Lintels for doors and windows are framed as in conventional framing.