The present invention provides one or more viewports formed at predetermined locations that allow inspections of an inside member of a closed wall system. The viewports can be disposed at predetermined locations that do not significantly impair the structural characteristics of the outward layers or inside members. In at least one embodiment, the viewports are formed in one or more outward layers during fabrication of a closed wall system. Generally, the closed wall system can be mass-produced in a manufacturing facility, although the closed wall system may be assembled at the job site.