| I would bet on a combination of sloppy workmanship and settling. I guess you could try checking the walls to see if they are plumb. The worst sign would be walls on opposite sides leaning the same direction. Look around for things like other trim or cabinets showing signs of shifting. If the more you look, the less you like what you find, it might be better to have a professional look at the house. Perhaps the home inspectors many buyers use.
While you have the trim off, you may even be able to straighten up the door frames. Also make sure the outside door and the windows are all well sealed to the outside and the gaps around them stuffed with insulation. Maybe even use the instant foam stuff. Could knock a hole in your utility bills, and keep the house from getting so dry in the winter. It should help keep noise out too. |