How to Install an Interior Door

Figuring out how to install a door starts with choosing what kind of door to hang. There are two types of interior doors, a prehung door and a slab door. Slab doors, also known as blank doors, include just the door and not any part of the frame. You’ll have to attach the hinges to the door and that requires very precise work. With a prehung door, the door is already on the frame and much easier to work with. Your final choice will depend on your skills and budget.

No matter which type you choose, below are the basic tools you'll need for installing a door:

• Measuring tape
• Hammer
• Screwdriver
• Drill
• Shims
• Level

Tip: Measure your door frame precisely. Measure twice to be sure.

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.