Besides the frame, doors can be damaged by a variety of factors.
If they aren't repaired, they can cause issues such as sticking, jamming, and leaks. Some homeowners choose to repair these issues themselves, but others will need the help of a professional to replace their doors. These stopgap measures don't address the real problem and will only lead to more damage and higher heating bills. Fortunately, the process of door replacement can be easy and affordable if you take the time to research your options.
Aside from the structure, the quality of a door's seal is also important. Older doors may be cracked, or have rotted wood, affecting the way they function in the interior. However, there are other factors that you should take into account as well. If your door is leaking, it's best to replace it. It will last longer, and your energy bills will be lower, as it won't be leaking.