My son purchased a 150 yr old stone house with the thick stone walls your photo’s indicate. He has the new windows installed and wants to build the interior frames for three windows to match other windows that were replaced before he and his wife purchased the home. It would seem the frame should be built to set into the opening and then fasten. Do you have photo’s of the finished framing and how you did it.

Hi Charles – I don’t have any progress photos on the new window frames – sorry. To explain it simply: You need to build a ‘picture frame’ that is the exact size of the window, and the depth of the wall cavity. You slide this into the window so that it butts against the sill etc. squarely.  You then need to shim around the perimeter of this ‘pcture frame’ until the entire thing is square, tight and flush. Once this is done, you then secure the frame in place by driving finishing nails through the frame AND shims into the existing wall, and then fill the remaining cavities with low-expansion foam.

Sorry I can’t be more help.  Congratulations to son!