Abstract: An improved panel wall system uses modified battens to simplify the installation of doors, windows, and accessories. An improved mounting system for windows provides flexibility of size and location, while providing for a substantially planar clean room surface. The mounting system used for windows can be adapted directly for mounting any flat accessory, or any accessory mounted upon a flat frame. An improved door jamb element allows the use of butt hinges to hang a door panel, while providing structural support. The improved door jamb element also provides for the on-site addition of a door to an existing panel wall system. An improved mounting system for a transom above a door panel simplifies on-site installation of the transom.