I'm cutting an egress window into my foundation and am trying to figure out the difference between rough sill height and finished sill height. I figured about 4". Is that about right? (I need to know because the floor to bottom of the finished sill can be only 44" with a max 7" riser.
Figure you will frame wood 2x around the perimeter of the window.
Then you want at least 1/4 inch space between the window framing and the window jamb bottom.
So add 1 1/2 inches for the framing and add 1/4 inch plus the actul thickness from the bottom of the jamb to the top of the sill, and thats the number that you subtract from 44" to get a location to cut the rough opening.
Keep in mind that 44" is max. height so if in doubt go a little lower than you think you need to be.