Hi, I'm a residential framer and about to replace all my windows and doors. I want to properly flash them, and have looked at both: http://www.youtube.com/watch?v=vaKXqFtHAss&NR=1 Carl Hagstrom's flex wrap video and http://www.finehomebuilding.com/how-to/install-replacement-windows-and-flashing-correctly.aspx Fine Homebuilding's article Typically we add 3/8 shims beneath the side jambs, and dividers of windows we install at work. This creates a gap for using low-expanding spray foam. However in both of the above demos, they don't seem to shim the bottom at all - it just sits on the bevelled siding sill pan. How would you insulate the bottom this way?

I read the fine home article and I think it is good but I disagree with the foam at the bottom also. My point is you foam towards the outside first. And you don't need filler strips. filler strips first would allow moisture and outside air to infiltrate. I would shim a window at the bottom to center it in the opening and then to level it. so it would not be a set amount.
I am in the process of replacing windows on my home and have some done. There are no interior trim as I am waiting to do them all at once. But they are far warmer and less leaking than the original frames that were done to mfg specs of 30 years ago. Both are insulated glass double hungs