The most common surprise on a 1981-era house is a spring rated for a door that's ten or fifteen pounds lighter than the insulated replacement going in. Hang the new door on the old spring and it'll lift hard, sag on one side, or wear the opener's motor out faster than it should. Winters here fall into a cold band rated severe, and an old, non-insulated door with a worn-out bottom seal lets a real amount of cold air into the garage - worth factoring in if the space is used for anything beyond parking. We also see original headers that were never built to carry a heavier insulated door plus a two-motor opener; if the framing's undersized, that's a repair to the structure before the door goes in, and we'll say so rather than hang the door anyway. One honest limitation: if the header needs rebuilding, we can flag it, but that carpentry work isn't part of a standard door install and may need a separate call before we can finish the job.