I'm rehabbing a structure from the 1850's. As you can imagine, nothing is square, level or plumb. The walls were originally plaster on top of true 2x4's.
I've brought the house down to the studs, and am going back with exterior sheathing (0.5") on top of true 2x4's (4.0") plus drywall inside (0.5"). That gives me an actual wall thickness of 5.0".
That tells me I should order my new windows for a wall depth of 5.0"
Problem is, the walls are not straight or consistent. Should I order windows with a little extra? Like 5.5"? I had experience doing this to my first house, which was also from the 1850's, and it took me forever to get the interior trim around the windows right. I had to cut shims, and wedges, because the walls were wavy. It was a huge pain.
Specifically: If my wall has a nominal thickness of 5.0", what is a sane amount of expected deviation? Maybe 0.25"? Should I order windows for a wall depth of 5.25" and just shim out the interior trim?