How To Restore A Square Interior Door?

Adjust the latch jamb with shims once the hinge jamb is plumb. Check the top and bottom corners with a framing square when both jambs are plumb. Put the door back in the casing with the hinge pins and test it to ensure it opens and closes easily. If you have a Knockdown steel door frame that’s twisted or out of square, fix it by cutting the nails on the latch side, cutting off 3/4″ from the bottom of the latch side jamb, and then using a standard door liner set.

Insert the pre-hung door into the door opening, keeping the edge of the jamb flush with the wall. Remove the door plug. Pry off the trim around the door frame on the inside of the room with a small pry bar and hammer to expose the rough opening studs and header. Line up a combination square with the old door’s hinge mortises and transfer their locations to the new door.

Chisel out the hinges by holding the chisel vertically and tapping it with a mallet to outline the gaps. You can replace the door or try to rectify it. If you prefer, remove the door, tip some wood glue into the gaps that have formed in the joins, tighten the screws on the top hinge, or replace two of the screws with longer ones on the top hinge into the jamb not the door.

Let the glue set up for an hour and then re-mount the hinges. Use a hammer to tap out the pins and place a thin piece of wood or a shim under the door first.