About 1.5 years ago we had some windows replaced in our rental unit in the entryway mud room. The old windows were just plexiglass sheeting. Because the unit was occupied when the windows were replaced, I never had a close look at the install until now, and I want to eventually add some casing (I am currently renovating this room, hence the dirty walls). The new windows were installed directly atop the sheetrock with no wooden stool beneath. The windows rest on a few shims that are wedged between the window and drywall. They did use some spray foam in the gap (not visible in image). Is this typical, especially in replacement of windows in old homes? Do I need to worry about insulation? There is no sign of water damage yet; the imperfections in the drywall (see image) appear to be from when the drywall cut was made. I live in Minneapolis.