Panelized systems are prefabricated components that brought to the site and assembled into the finished structure. Traditional constructions are often subjected to termite attack, mold buildups and have poor penetration resistance against wind borne debris. To overcome these problems, new type of composite structural insulated panels (CSIPs) was developed and is analyzed in this study. The concept of the panel is based on the theory of sandwich construction. The proposed composite panel is made of low cost thermoplastic glass/polypropylene (glass-PP) laminate as facesheet and Expanded Polystyrene Foam (EPS) as a core. The EPS core provides excellent insulation against heat, sound and vibration and withstands shear stresses while FRP facesheets primarily resist bending stresses. This study provides an analytical modeling for the CSIP floor member based on the experimental work previously conducted at the University of Alabama at Birmingham on full scale CSIP floor panels. A theoretical analysis was conducted to predict defection, flexural strength, and facing stresses of the CSIP floor member and results found were in a good accordance with the experimental ones.