A question about fitting stools and jamb extensions to old style windows: in a modern window, my understanding is that the stool butts up against the window frame. The sloping sill is outside that point and separated from the stool by the frame. Yes? But what about an old stlye window with a wooden sill that extends in to what would be the DW plane in a 2X4 wall? The walls are 2X6, so I need jamb extensions. So, shouldn’t the stool go OVER the sill? And if so, shouldn’t I cut an angled groove in the underside of the stool complementary to the angled edge of the sill? If I’m right, this means that that stool will nearly butt up against the inner surface of the lower sash (these are DH windows). And, if I’m right, because the stool is over the sill, a rather wide skirt is needed to reach the rough sill.
Just bought the new Taunton “Trim Complete” book, and am disappointed that it doesn’t address this issue.