How do you make sure that when windows are installed in a new build that they will be installed so that you won't have to buy custom made curtains? I am concerned about the length being correct.

As an example, we currently have a home with 8' ceilings, so full windows should be covered by the standard 84" curtain, right? Well they don't. I had to buy the 95" curtains and, even though we hung the curtain rods as high as possible, I still had to hem them all to make them fit.

I'm wondering if there is any way to prevent this when we build another home? That home will have 9' ceilings, so what length window looks proportionate with 9' ceilings and how do I make sure that the standard length 95" window coverings will fit over the window and frame?