do you know the size of your baseboard and crown moldings? That would be my starting point. I have arched top windows in my sunroom. The base of the window sits inside the baseboard molding. Meaning that the baseboard molding comes up above the window molding. The crown molding touches the top of the arched window molding. Overall, it looks cramped.

I'd figure up the molding heights for the base crown and your windows as well as the spaces between the windows and then see how much space you have left.

I think your local code might dictate how far away from the opening the light switch should be...... It's much easier to move a light switch now than it would be with final finishes in place. He's just being lazy not wanting to move it.

I think you need to consider the outside elevation of the house when you consider window height as well as the inside. It's hard to say what is "correct" without considering both aspects, I think.

All good points. My thinking right now is 8 inch for coffered and tray ceiling. If we start windows 1 ft from the floor this will leave enough room for windOw trim and molding - assume 5 inch for molding and 4 inch forwindow trim. So the top of the window would be at 8 ft. Add trim and you are at 8ft 4 in right at the start of the tray ceiling. Do you think the window from and tray ceiling should have a slight separation?

Don't forget that if your windows are within 18" of the floor the glass must be tempered which will increase the cost of the windows.

Yes but not if they are within 9 sq feet visible glass. My 5 ft and 2 ft transoms are less.