Table of Arch Window Sizes with Colonial Grille. To see Renaissance Grille click here Casement / Awning compatible Grilles for arch unit widths 2'0-1/8" through 4' 8-1/2" have a 3/4" interior wood grille profile for compatibility with casement and awning window grilles. Grille profile for FrenchwoodŽ patio door compatible units FrenchwoodŽ patio door compatible Grilles for arch unit widths 4' 11-1/4" through 11'-9" have a 7/8" interior wood grille profile for compatibility with FrenchwoodŽ patio door grilles. NOTE: Grille patterns for units with shoulder heights of 12 inches or less do not include horizontal dividers. "Unit Dimension" always refers to outside frame to frame dimension. Dimensions in parentheses are in millimeters. Arch window units are stationary. Combinations of window units joined together may require horizontal or vertical reinforcement. This reinforcement should be specified by a professional engineer. Contact your Anderson supplier for more information. When ordering, be sure to specify color desired: white, sandtone, or TerratoneŽ. Grille alignment with other AndersonŽ products. All vertical arch window grille members were designed to be equally spaced. Vertical alignment may not coincide when units are transom joined. All horizontal grille members were designed to line up with corresponding casement sizes. Special order arch window grilles are available to achieve proper alignment.