i recently installed a pre hung exterior steel door for a friend of mine. it seemed simple enough i have installed an exterior door before. first issue i encounterd was there was no sill plate when i removed that old door. well a trip to home depot fixed that. after making sure my rough opening was plumb ia installed the door. a few minor adjustment to the door it was perfect. it opened and closed with no problem.\ i installed the knob and strikerplate worked like a charm. to insulate i used that spray expanding foam. now fast foward a week i get a phone call door wont close. i go over to check it out and the door shited a good 3/8 of an inch in the cold. in my mind door cotrast in the winter its been below 40 since december. i am at a loss any ideas was able to fix it but now there is a good 1/2 inch gap at the top and bottom of the door. i have never had this problem.