Got a door that was trimmed off and rehung without getting repainted? Wood doors must be painted on all six sides (front, back, top, bottom and on both edges) because unpainted tops and bottoms – especially on exterior doors – allow moisture to be absorbed, which causes cracking, warping and paint failure. Bottom edges commonly are left exposed when new carpeting is installed or when a new threshold is put in place, and the door is trimmed for greater clearance.
If the bottom wasn’t painted before the door was rehung, you might be able to paint it while it’s in place. First cover the floor with a plastic drop cloth. Even a large plastic trash bag will do. Swing the door open over the plastic and use a slim roller or a small foam brush to paint the bottom of the door. You also can check the paint coverage by holding a small mirror beneath the door. Cleanup for this method is faster and easier than if you were to remove, paint and replace the door.