How to Measure

Measure all 4 sides to 1/16” and record the actual measurement. Do not average. Don’t bend the tape into the corner. Instead add the tape case dimension to your measurement. Measure exactly where the window will be mounted.

The Innerglass Compression-Fit window needs 3/4 “depth in the window opening for mounting, 5/8” is possible but call us. The double hung and horizontal sliding interior storms need 1 1/8” depth in the window opening. Watch for obstructions such as window hardware. Screw heads and recessed pockets for the window stops are generally not a problem if they don’t stick out more than 1/16″.

To check for out of square, notice the framing squares at the left and right bottom corners and the 2 lines under each framing square where you record the gap on the worksheet. Start tight to the left side and slide the 24” side down until it touches the sill at either the corner or the end. The framing square is always held tight against the side so that any gap will show up at the bottom. If the window is square at the bottom, you would record a “0” at each of the 4 lines under the framing squares. If the gap is 1/16 or less it is effectively square.

For example: If a window sags down to the right the gap measurements could be 0 ¼, 0 ¼.

Place the framing square against the right side of the window and repeat the procedure. Think of this as a snapshot of each bottom corner. In reality they overlap but for clarity they are separated and are not to scale.

Next lay the 24” side of the framing square on the sill to check if the sill is bowed up or down, if so give us a center vertical measurement and draw an arc showing the bow.