How to Install an Interior Door

If you are replacing an interior door with a prehung door, here’s how to remove the existing door and its frame.

• Loosen the trim with a stiff putty knife.
• Use a pry bar and block of wood to remove the trim without damaging the wall.
• Take your time. If the trim is in good shape, you can reuse it with any prehung door with a one-piece jamb.
• The head and inside jambs are usually nailed together. Remove them from the opening at the same time.
• Pry the side jambs away from the studs.
• Then pry down the head jamb.
• Make any changes to the wall or door frame before installing your new prehung door.
• If necessary, paint the door trim.

Once you have removed the old door and prepared the doorway, you can start on the first step in how to install an interior door.

• Slide the prehung door into the rough opening.
• Put the door in the opening and slide it until the jamb is flush with the wall.
• Double check to be sure the door opens in the desired location and direction.

Tip: Prehung doors are often heavy and hard to maneuver alone. A helper makes it easier to lift and hang the door.

Installing a door properly means it will open and close smoothly. This step helps that happen.

• Use a level to check that the door is straight. Add shims to adjust the level and make sure the jamb is plumb.
• The door frame should be slightly smaller than the opening it fits to allow for adjustments.
• Slip shims under the side jamb until the head jamb is level.
• Shim between the side jambs and the studs to fill in the spaces between them.
• On the hinge side, start with the bottom and top of the jamb. Shim between the hinges and studs.
• Position the shims so that about half of them are above the hinge.
• On the latch side, shim at roughly the same places and at latch level.
• Check the level of the door again.

• Drive two #8 finishing nails through the frame, through the shims and into the studs.
• Drive two nails through each shim about an inch from each edge of the jamb. Nail one about a 1/2-inch above the other.
• Before driving the nails home, open and close the door and make any necessary adjustments.
• When you’re satisfied with the way the door performs, finish driving and then set the nails.

• Nail the trim to the jamb and studs.
• Drive #6 finishing nails through the trim and into the studs behind the wall. Space these nails about 16 inches apart.
• Trim any exposed shims by scoring them with a knife and then breaking along the line.
• Following the directions above, cut and install the trim on the second side of the door.

• Once the door is hung, attach the backplates and door knobs.
• Make sure not to screw the knobs on too tightly.
• Add the lockset and strike plate.

Tip: Prehung doors typically come with attached hinges and pre-cut places for the doorknob and strike plate. The doorknob, lockset and strike plate are sold separately.