Abstract: The specification discloses a prefinished vinyl wall system for modular construction in an office building and a method for installing the same. Prefinished wall panels are dimensioned to abut with one another along their lateral edges. The panels are cemented to C-beams located just behind the panels on both sides of the joint. Staples are inserted along the lateral edges of each panel to engage a freely floating T-section disposed behind the joint formed by abutting panels to retain the panels in alignment until such time as the panels are permanently secured to the C-beams. The exterior portion of the lateral edges of each panel are beveled to form a V-junction on the finished side of the panels at the joint to give the panels a professional, workmanlike appearance.