I’m building a house with round top windows that are inset 2″ (I don’t want to simply stick the windows on to the outside of the house, so at each window, I framed 2×4’s flush to the inside of the 2×6 wall.) I have the sides and bottom figured out; my problem is figuring out how to frame & waterproof the rounded tops — both the 1.5″ face that the window will attach to and the 2″ deep surface that connects the inset face to the outside wall. I want to have clean, round stucco edges that will nicely highlight the inset windows (i.e. no exposed flashings or trim boards). I see these windows around, so I’m sure there are established techniques for how to frame them. I’m at the point now of framing the rounded tops, and I’m wondering whether I should frame them now or wait until I get the windows and frame them as I fit each one. In all, there are twelve round tops plus three circular windows — so, any framing & rainproofing tips you could offer would be greatly appreciated.

Thanks a lot.

By the way, most of the rough opening widths are 22″. I’ll be using factory-built aluminum windows.