Doors are pretty complicated pieces of machinery, comprising of multiple different parts – one of which is the ‘door jamb’.
Definition of a Door Jamb
Let’s start with a plain English definition of a door jamb: a door jamb consists of the posts which sit on either side of the door, forming the vertical portion of the frame.
What’s the Difference Between a Door Jamb and Frame?
Simply put, the jamb is a specific part of the frame. It’s there to take the weight of the door, as well as help keep the rest of the frame square and stable. Your hinges are affixed to the jamb on one side of the door, while the bolt passes through the jamb on the other side.
The ‘plumbness’ of a jamb has a significant influence on the function of the door. Just a few degrees outside of 90°, and you’ll find that your door rubs against the frame, or that the bolt doesn’t properly align. If the surrounding walls aren’t entirely plumb, you can correct this with the help of a few strategically-placed shims.
It’s also crucial that the jambs are of the same height, and not too tall or too narrow – if so you might end up with excessive gaps (or no gaps at all).