How to Hang an Interior Door
If you want or need to replace an interior door, take heart. It's not as difficult as you might think, and it's much easier than hanging heavy exterior doors. Here are the basics of how to hang an interior door in an existing door jamb.
Choose a door that fits your opening. You may have to trim it slightly to get a good fit, but it should be roughly the same size as the opening. Use the old door as a template, and trace around it with a pencil to see if you need to remove any of the new door to make it fit. There should be 1/8inch clearance on the top and sides of the door, and 5/8 inch clearance on the bottom to allow for carpet.
Using the old door's hinges as a template, mark the edge of the new door to indicate where the hinges will go. Use a hammer and chisel to remove enough of the door so that the hinges lie flush against the door when attached. Once they lie flush, attach them with screws.
If you are simply replacing a door, the holes for the door knob latch are already drilled into the jamb, but you need to make sure that the door knob on the new door lines up with the old hole in the jamb.
Use the location of the door know hardware from the old door as a guide to drill the holes in the new door, if necessary. Install the hardware, and make sure it isn't loose in the new door.
Once you have attached all the hardware to the new door and trimmed it to matchthe size of the original door, you can hang it in the existing door jamb. Using the doorknob as a handle, lift the new door into place, lining the hinges up with the ones on the door jamb.
Replace the pins in the hinges, and open the door to make sure it clears the floor properly. Now, you have a new door that looks great and fits as well as the old one did.