Professional Measuring

The single biggest measuring decision is mount type. An inside mount sits flush inside the window frame for a clean, built-in look, but it requires at least 2 to 2.5 inches of casing depth to clear the headrail and brackets — not every window has it. An outside mount covers the frame entirely, which works on shallow casings and can also make a window look larger, but it needs enough flat wall space around the frame to mount into. We check casing depth and wall clearance on-site before recommending either option, rather than guessing from a photo.

Most homes settle unevenly over the years, so a window that looks square rarely measures perfectly square in all three dimensions — width at the top, middle, and bottom can each differ by a quarter inch or more. Custom window treatments are built to the smallest of those measurements, and getting it wrong by even an eighth of an inch is the difference between a shade that operates smoothly and one that binds or leaves a light gap. We measure every window in three places, note obstructions like handles or locks, and record it all before a single order goes in.