In a project when you get to the trim work, that’s when things really start to shine but there are many ways and styles to case or trim a door.
Below is an example of a simple and clean flat casing. In this case the vertical pieces are 1 x 4″ boards that are integrated into a 1 x 6″ band the goes around the top of the room. As you will notice here these are actually door openings with no door but the principle of continuity is shown.
You could also do something like this using a fluted trim board and rosettes at the top. At the base of this style of trim you would probably use plinth blocks to tie into the baseboard.
In case you weren’t sure what a plinth block was and how it transitioned the two trims, I thought a photo would help clarify things.
We now come to an important aspect of door casing that can’t be overlooked. Door casing naturally goes to the floor and at the floor is the baseboard. These two elements have to work together to provide a consistent and uniform look. If they are co-ordinated then you end up with beautiful finished room.