Be custom-fitted

Be custom-fitted to each prime window opening to match the size and shape of the existing window opening  − Be installed in a vertical position only; sloped installations shall not be permitted − Be mounted on the interior side of the prime window opening to achieve an isolated air space between the two glazing materials of 3/4 inch minimum to 4 inches maximum − Be permanently attached to the prime window opening and provide a weather tight seal establishing an air tightness greater than that of the existing exterior prime window over which it is installed  Clearance must be allowed for prime window light operation, removal, and cleaning. Where the design of the prime window precludes mounting the storm window to cover the entire window opening, the installation must be accepted in advance by TVA and the customer.  When subframing materials are used for mounting interior applied, thermoplastic storm windows, subframes shall be permanently attached to the prime window opening or mounting surface with mechanical fasteners positioned on approximately 12-inch centers to provide a secure installation for the storm window assembly.  Subframes shall be effectively sealed to the prime window opening by a continuous bead of approved caulk. The sealant shall provide a permanent seal between the storm window assembly and the surrounding prime window opening.   Thermoplastic hook-and-loop mounting systems, such as Velcro, or equivalent, are not permitted.
Section 2C   01/16/2007
 15
 A thermoplastic insert panel may be attached to its framing members by use of magnetic strips if the following conditions are met:  − The magnetic holding force of the magnetic strip shall be a minimum of 6-1/2 pounds per linear foot with a maximum of 10 percent variance at zero air gap around the window perimete