On Oct 25, 11:16*am, kc wrote:
I have a door opening of 351/2" wide X 781/2" high. So far I cannot
find an off-the-shelf storm door that fits this size opening.

Some storm door manufacturer's brochures state that their standard
storm doors can be ordered in custom sizes. If you've had this done,
how much did it cost you, or how much % or $ over the same door in a
standard size?

Thanks in advance for any ideas on this.

A standard 36" storm door & frame should fit your opening. The actual
width is narrower and the length is longer to accomodate variations
like yours. For length you trim the frame to correct size & adjust
the door's bottom plate. For width, you center and the wide lips of
the frame will cover any variation.

KC