One of the tips in repairing a door is identifying the exact problem with the door before starting the repair. Some of the common problems with doors are swelling or sticking, drafts and sagging.
Repairing a sticking door involves sanding down the section that sticks and causes friction. Use a piece of carbon paper to identify the section. Seal up the sanded area to avoid moisture problems.
You can repair a drafty door by either installing a storm door or adding weather stripping. Adding weather stripping is a cost-effective way to deal with drafts.
To fix a sagging door temporarily, sand the upper door edges. To fix them permanently, replace the screws on the upper hinge leaf attached to the doorjamb with 3-inch decking screws.