Inspected a 50 year old home the other day that had numerous items hidden by the home owner, the reason he hid them was because of a failed sale from a previous home inspector. Come to find out none of the doors would close due to some signifigant settlement or foundation failure. He then took it upon himself to cut the doors at an angle to fit the jambs, I only caught it because the tops of the doors looked a little jagged. I then put my torpedo level on them and noted headers were out of level by 3/8" in some areas…
Recommndation: Several door jambs out of square, this condition indicates movement and warrants further evaluation by a licesned structural engineer.
What did you find in the basement or crawlspace?
Did the foundation condition look fine?
Were the floor joists properly supporting on sill area and center load carrying beam?
Were there plenty of support posts/footings throughout?
It’s probably just too much paint on the door. Did the doors look repainted? Was it a sloppy paint over paint job? In my 50 year old house, two doors stuck for this very reason. It was nothing a bit of sanding did not fix.
Even this should be called out (for safety reasons, my HI did) but I hope you are sure of the cause.
Cracking off doors and window corners? Wall repairs in these areas? New paint? If the house is moving that much there should be visible evidence in the int. and ext. wall coverings. Got to have access to that crawlspace!
I,d recommend a qualified foundation repair contractor, then if correction requires design needing calculations, an engineer. Otherwise the client has to pay both for sure, since an engineer’s not going to fix anything.