For starters we do offer a
stacking chart that will give you a general idea of what the "stack"
will be. [look under measure + install]. Remember these are just approximates
and the exact measurement will vary depending on length and material/lining
You can view stacking chart
After you have checked out
the stack chart, if you are still concerned you should consider doing
an outside mount and installing the shade high enough above the window
so that when up the shade does not block the window.