Ultimate Double Hung G2 IZ3

Supplemental Installation Instructions

Revised on 2019-06-13

left arrow Go Back to All Installation Instructions

ABSTRACT: These instructions are applicable for the following StormPlus products:

  • Ultimate Double Hung G2 IZ3
  • Ultimate Double Hung Round Top G2 IZ3

Use these instructions in conjunction with the Ultimate Double Hung G2 instructions.

NOTE: Numbers listed in parentheses () are metric equivalents in millimeters rounded to the nearest whole number.

Fastening Options

Installation methods outlined in this instruction are aluminum nailing fin (default method), through jamb fastening, and structural brackets.

Operator and transom units require one of the following methods:

  • Aluminum nail fin with jamb screw near the check rail
  • Structural brackets
  • Jamb screws

Picture units require structural brackets and jamb screws are the only options.

Performance Brackets

1. Operator units that have performance brackets require a screw through jamb in the pre-marked hole adjacent to the upper jamb bracket(s) Figure 1 and through the center of the lower jamb bracket(s) Figure 2.

Figure 1
Figure 2

Aluminum Nail Fin

NOTE: Units with vinyl nailing fin must use an additional method of fastening such as through jamb or structural bracket installation.

1. Manually fold out the nail fin until it is perpendicular with the frame.

2. Take care during handling and installation to not damage the corner gasket. After the window is secured in the opening fold the supplied drip cap to an "L" shape as shown and install according to the flashing instructions. See Figure 3 and Figure 4.

Figure 3 Shipped Position
1 Corner gasket
2 Aluminum nail fin
Figure 4 Ready for installation
1 Drip cap


Shimming and adjustment must be done prior to permanently fastening the nailing fin.

3. Fasten the nailing fin with 2" roofing nails spaced 4" (102) maximum from the corners and 8" (203) maximum around the perimeter. See Figure 5.


Transom Units: fasten the head jamb with screws spaced 4" on center from the corner and 24" (610) max on center.

Figure 5
1 2" from corner
2 4" on center around perimeter

4. On operator units remove the interior jamb cover to install the jamb screw. See Figure 6.

Figure 6

5. Install screws near the check rail.

Through Jamb Installation

NOTE: For units installed with installation screws through the framing members, be sure to shim at each fastening location to avoid bowing/distorting the jambs.

1. Remove the interior wood cover, exterior mid-clad cover, and vinyl assembly for access to installation holes. Use a stiff putty knife or small flathead screwdriver to carefully remove the covers. See Figure 7 and Figure 8.

Figure 7
Figure 8

2. Center the window in the opening. Jambs must be straight and level. Apply #8 x 3" screws until snug through the pre-marked holes, do not over-tighten. To permanently secure the unit to the framing members. See Figure 9.

Figure 9
1 Approximate screw locations
2 Pre-marked locations

3. Install #8x 3" screws through the head jamb. See Figure 10.

Figure 10

4. Replace the covers. Operation of the window may be affected if the components are not seated properly. See Figure 11

Figure 11
1 Replace the bottom jamb cover first
2 Replace the top jamb cover second


When trimming the window, make sure the fasteners will not penetrate the balance tube pocket or clutch assemblies.

Structural Brackets

NOTE: For more information on structural bracket installation, please refer to the instructions included with your window.

1. Structural brackets require spacing 4" (102) from all corners and 12" (330) on center around the perimeter. See Figure 12.

Figure 12
1 4" (102)
2 12" (330)

2. Wrap the brackets around the framing/buck/opening, and fasten with two #8 x 1 1/2" screws. Angle the screws approximately 15 degrees away from the window. Always shim above or behind the installation brackets. See Figure 13

Figure 13
1 Shim
2 Bracket

Mulled Units

1. All mulled units require fastening with two screws or structural brackets on each side of the mull joint, no more than 6" (152) from the mull joint. Additional structural brackets should be placed at the corners to level the unit. See Figure 14.

Figure 14
1 6" (152)