How to Identify Your Window Mounting Surface
The mounting surface is the solid part of your window that the storm frame attaches to, and it decides where the tape measure goes.
Which one do you have?
Stand outside and look at your window. If an old storm window is in place, take it out first, then match what you see to one of these three.
Inside the opening
A recessed ledge sits inside the opening beside the existing sash.
Measure between the opposing inside edges at the ledge, at the top, middle and bottom, and keep all three readings.
Over the flat trim
A flat face of trim surrounds the window, and the frame covers its inner edge.
Record the opening and the flat trim available on each side, and keep any overlap allowance separate.
- A storm panel already in a channel
Existing storm track
A channel already holds a storm panel.
Choose the existing exterior storm track option when you measure, and we confirm the details with you.
The sill
Look at the sill from the side, because it ends your height measurement. A sloped sill is one continuous slope that falls outward. Measure to the sill surface directly below the head stop, where the frame will sit, and keep the tape at that plane as the sill slopes away.
A drop sill has a vertical step between an upper shelf and a lower outer seat. If the frame sits in the drop, measure to the lower seat, and photograph the step and its depth.
Do not subtract anything
Enter your measured sizes unchanged. Any factory deduction or overlap is confirmed for your frame and mounting method before it is built.
Not sure? Send photos
Stop before you order. Send the full opening and close-ups of the top, both sides and the sill, and we will take a look at the mounting surface.
Send us photos
We will look at your mounting surface
Ready to measure?
Step-by-step measuring guide