Why professional sizing beats DIY for your unique window shapes, and how the nine-point measurement standard prevents light gaps, binding, and costly remakes.
Professional measurement is non-negotiable for custom window treatments. A margin of error as small as one-quarter of an inch in the wrong direction causes light gaps along the frame, prevents smooth mechanical operation, or results in a shade that cannot seat inside the casing at all. At that point the treatment must be remade, and the homeowner pays twice. Our designers measure every opening correctly the first time, so you never face that situation.
Every window our team measures is recorded at nine separate points, three widths and three heights, not at a single center point. This accounts for the reality that very few windows are perfectly square, especially in Aurora homes built before 1970 and in newer Naperville developments where initial settling has already begun.
The narrowest width and shortest height are used for inside-mount orders so the treatment clears the casing. The widest width and tallest height are used for outside-mount orders to guarantee full coverage. This single discipline eliminates the most common cause of custom blind returns.
Most homeowners measure once, at the center of the window, using a standard tape measure. That approach misses out-of-square openings, crown moulding intrusions at the top of the casing, and baseboards or sill depths that affect bracket placement. It also misses the deduction required for inside-mount products: every manufacturer specifies a different deduction per product type, and applying the wrong deduction produces a treatment that binds in the frame on the first operation.
| Common DIY measurement error | Consequence |
|---|---|
| Single center measurement only | Out-of-square opening causes uneven gaps on one or both sides |
| Forgetting the manufacturer deduction | Blind or shade binds in the frame and cannot operate properly |
| Not checking sill depth | Inside-mount product ordered too deep for available casing clearance |
| Rounding to the nearest inch | Gap at frame edge allows light bleed and reduces thermal performance |
| Not accounting for obstruction clearance | Headrail collides with window crank handle or lock hardware |
Arched, circular, and elliptical windows require a physical template, not a tape measurement. Our team applies a flexible template material directly to the opening and traces the exact curve. That template goes to the manufacturer for custom fabrication. Off-the-shelf products adapted to fit an arch always leave gaps at the curved section. Custom specialty-shape shutters from Norman Window Fashions are built to exact template specifications, no adaptation required.
A bay window consists of three or more panels set at varying angles, typically 30, 45, or 90 degrees from the wall plane. Each panel requires an independent measurement. The installer must also account for the stacking space each treatment needs when raised; if that space is not calculated per panel, raised treatments overlap and block the view or collide with adjacent panels.
Sliding glass doors and openings wider than 96 inches require vertical blinds, bypass shutters, or panel track systems. Each configuration has specific clearance requirements at the wall or pocket where panels stack when the door is open. Measuring for these correctly requires knowing the door stack direction and the depth of the wall pocket, both of which are confirmed on-site.
Narrow sidelights flanking entry doors can be as small as 8 inches wide. Products available at this width are limited, and bracket placement requires precision to avoid drilling into the door frame itself. Transom windows above doors require treatments that can be accessed from below, which affects both product selection and the type of lift mechanism specified.
There is no charge for the measurement visit, and the measurements on file are yours to reference for the life of the treatment.
Our designer measures every opening at nine points and confirms the order with you before anything is made. No obligation, samples brought to your home.
