1. Measure each window casing.

•Record each measurement on this convenient printable chart.
•Work left-to-right, floor-by-floor.
•The recorded height should be the measured height from top to bottom of the casing minus 1/4″. The recorded width should be the measured width from side to side of the casing minus 1/4″. This will give 1/8″ clearance all the way around.


Design Wind Speed
(MPH, gust)

Maximum Allowable PLYLOX™ Clip Spacing (inches)

Nominal Recessed Width of Window (Inches)

24 36 48 60 72 96

Clip Spacing in Inches on Vertical Edges


24 24 24 24 16 8
120 24 24 24 16 8 6
130 24 24 16 8 8 N/A
140 24 24 12 8 6 N/A
150 24 16 8 6 N/A N/A


2. Cut 1/2″ plywood to the recorded size of each window.

•Mark each cut piece with its label, such as FF1, the window at the left front of the house on the first floor.
•If you keep the chart and label the plywood covers, you won’t need to label the casings.

3. Place the PLYLOX clips on each plywood cover (if the window is 24″x24″ or smaller, only two PLYLOX clips are needed).

•Each clip should be placed on the edge of the plywood cover no more than 24 inches apart.
•Make sure the tension legs are facing towards you.

4. Push the plywood covers with the PLYLOX tension legs to the outside firmly into the casing.

5. PLYLOX works as well in round windows as they do in rectangular windows. You can adjust the number of PLYLOX clips used to account for different shapes and sizes of windows.