Cut out 2 pieces of cardboard the same size as the minimum flush mount depth. (Regular size business cards work, too.) You’ll use these as placeholders to show where the headrails for each shade will go, and to make sure they won’t overlap or interfere with each other when installing and operating your window coverings.
2. Position the pieces of cardboard so the front edges meet in the adjoining corners and tape into place, as shown here.
3. With a pencil, lightly mark each end of the cardboard pieces where they come to an angle and meet in the middle window. Measure between the marks to get the measurement of the middle window.
4. Starting from each mark in the center corners of the middle window, measure the width of the window to the right and then out to the end of the window on the left.
5. Double-check all of your measurements, rounding the width of each window up or down to the nearest 1/8”. (Automatic deductions are taken on inside mounts at the factory to ensure a proper fit.)
6. Measure the height of each window. (Watch this video to see how.)
7. Repeat these steps as needed, depending on the number of windows you have.