door-frame
When opening this door more than 90 degrees or so, it hits the floor, which I checked, it's level.
It seems the doors was not hung properly.
2 choices, when open as far as it will go, just produce a line 1/4" off the floor and shave off that much wood. Other choice is to unscrew hinges and pull the top hinge in a bit, and middle hinge half as much.
What is the better choice? I've lived with this a very long time, but it's time to fix this.
I'm not sure about ChrisF's suggestion since I've never had that particular problem (with the door rubbing on the hinge side) - is the issue that it's hitting the frame on the hinge side or the doorknob side?
If it's hitting the jamb on the doorknob side (as if the door is now too wide) then the usual solution is to trim down the door. Usually I would run it through a table saw, but you could do it with a circular saw as well if you are really careful.
Just make sure to trim off the knob side rather than the hinge side so you don't have to worry about mortising out new spots for the hinges (and then risk being off on the top of the door)
One approach is an oversized pre-cased, split-jamb door. These have casings (room side moldings) pre installed to the jamb and are attached separately from each side. The joint in the middle is hidden by the stop (the molding that the door actually rests against when closed). This is a home center site describing the process.
These doors probably would have to be special ordered and cost more than standard prehung doors. An alternative is to create your own jambs using standard clear boards. This does require some skill with either a chisel or router, but is not beyond the skill level of a fair DIY carpenter.
You could also install a standard pre-hung door with the jamb on the hinge side flush to the outer edge of that wall. This will leave the other edge of the jamb about 1/2 inch recessed, the thickness of the soundboard. Just putting a narrow piece of board the same thickness as the jamb would work (there is no structural issue). However, butt aligning boards generally does not look good - the edges shift slightly and it always looks like an unintentional (or unprofessional) joint. The standard way to solve that is to create a reveal. This is a small step in level between two adjoining lengths of wood.
You could put in a simple square edged molding (or thin strip of board) that is set back from the inner edge of the jamb opening about 1/8 to 3/16. If the soundboard is tight up against the jamb (it really shouldn't be, but sometimes is) use a board/molding slightly thinner than the jamb. Other wise, just slid it back a bit. Then when you measure for the casing. create a second small reveal set back from this filler strip.
Another, simpler, but less elegant approach, is to use a backband or cap type molding.
The one illustrated is a bit deep, but you can probably find one smaller and simpler.
Putting the shorter edge on the outside edge of the short jamb with the thin edge overlapping onto the inside edge of the jamb. Then nail the casing agasint the cap/backband. Becasue the door opens on the hinge side, this inset molding should not interfere with functionality.
Best Answer
Two minutes to mark the bottom of the door whether it be a 1/4" mark or a 1/2" mark up from the floor, 10 minutes to pull the door pins, 10 minutes to set up a workbench of a sort, and 20 minutes to cut it after you score the mark with a straight edge and razor knife and reset it in place. A little time spent for a long time reward.
If the door does not close or open on its own from being out of plumb or however it is not set properly, this is a little time spent in comparison to a resetting of the door. If it does open or close on its own and it is a problem, the door is really out of whack and could use a resetting. Usually a door, in my experiences , can be up to a 1/4" out of plumb in either direction and the door leaf will stay where it is placed. Anything a 1/4" and more will move on its own, unless of course it is in the closed and latched position.