These directions summarize some supplies and steps we have found helpful when working with doors. This information is offered for use at your own discretion, and it may or may not be applicable to your specific project. Please consult a professional for more detailed advice regarding your project. 



-Jamb – the frame to which a door is secured

-Slab – the actual door itself, without the frame or hardware

-Panels – decorative squares or sections of the door

-Hinge – a metal piece of hardware that attaches to the door and jamb and allows the door to swing open

-Rail – horizontal members of the door structure, found at the top and bottom of the door

-Stile – vertical members of the door structure, found on the hinge- and handle-side of the door

-Casing – the external decorative structure that attaches to the wall, frames the door, and covers up any unsightly edges

-Sill or threshold – the bottom part of a pre-hung door that sits on the ground, touching the subsill, in exterior doors

-Subsill – the floor in door frame, where the door sill will rest

-Weather Stripping – long rubber pieces that go around the door and help seal it from water and air

-Bore – the hole where a door handle will go

-Mortise – the holes in the door that hold hardware, such as hinges or latches

-Lites– the glass set into a doorframe that lets in light, often found on the side or top of the door



-Tape measure, for sizing up the door and finding a good replacement

-Sawzall, for cutting out the current doorjamb

-Flatbar, for prying casing loose and knocking the hinge pins out of the original door

-Hammer, for knocking the hinge pins out of the original door

-Utility knife, for cutting around the casing

-Level, to check if the door and doorjamb are plumb

-Shims, to make the door plumb (These can be cedar shims specifically made for installing doors and windows, or you can use any thin wood or paper material.)

-Beveled board, if you need to level off the subsill

-Drill, to create a hole for the nails (Use a bit size slightly smaller than the nail)

-Finish nails, 8d to 16d, depending on thickness of jamb, to hold the doorjamb in place

-Caulk or expansion foam, to weatherize the space around your door



-Fiberglass – an enclosed foam makes it the best for insulation, more resistant to dents than wood, doesn’t usually warp over time, most expensive, usually less than the standard 80″ in height

-Wood – more authentic-looking than fiberglass doors’ appearance of wood, warps over time, won’t rust, requires routine maintenance (sealing) for longevity, more expensive than steel

-Steel – can’t be trimmed, inexpensive, won’t warp over time, can rust



  1. Determine wheter the jamb needs to be replaced—not just the door slab
    1. Is the jamb warped, rotten or uneven? Does it bow and pucker? If so, the jamb must be replaced
    2. If you want the door and jamb to match up very closely, it is often better to have the replacement door matched to a jamb before installing, rather than replacing the door only and trying to match it up to the old jamb. If  the replacement door is nearly identical to the old one, matching up a new door to the old jamb may not be too hard
    3. Can you handle a door with a jamb? Though installing a pre-hung door is often simpler than installing a door slab into an old jamb already in place, installing a pre-hung door is definitely more of a challenge to physically handle. The job is best done with two people
  2.  Measure the current doorjamb
    1. Measure the height on both the knob and hinge side of the door
    2. Measure the width at both the top and bottom of the door
    3. Measure the depth
    4. Most interior doors are usually about 1 3/8” thick, and exterior doors are usually 1 ¾” thick. Standard heights runs in 2” increments
  3.  If possible, measure rough opening. The rough opening is the opening left when the door and jamb are removed. You can see it when you remove the casing
    1. For an exterior door, you usually do not want to open your home up to the elements, if you don’t have a replacement door
    2. But, if possible measure the height of the rough opening on the knob and hinge side of the doorjamb
    3. Measure the width of the rough opening at both the top and bottom of the doorjamb
    4. The rough opening is usually 2” bigger than the door in width and height
    5. The jamb should not fit too snugly inside the rough opening. About ¼” of room on each side is a good estimate of the distance between the jamb and the rough opening. You can leave a bigger gap, with the right insulation and covering
  4.  Finally, determine the swing of the door, and note where the handle lies. Take note of how it works for the space inside and outside your house
    1. Each place has a different way to determine the swing of the door. When in doubt, describe the way you determined the door swing to a customer service rep
    2. Below is Second Use’s criteria for determining door swing:
      1. Go to the push side of the door
      2. From there, put your back to the hinges
      3. Extend your arms
      4. If the right hand is closer to the door knob, you have a right hand door, and vice versa
    3. You may choose a replacement pre-hung door with a different swing or handle. This is fine, so long as it works for your space
  5.  For the simplest door replacement procedure, find a pre-hung door the same size as your original one
    1. Mentioned earlier, it’s possible to select a slightly smaller pre-hung door than the original, if you have insulation and covering for it
    2. Ideally, your selection will give you about 1/8” gap between the jamb and rough opening, on both sides and top. Some companies put small, square spacers around the door to ensure this gap and prevent over-shimming
    3. Do not select a larger pre-hung door than the original. Too tight of a fit in the rough opening may ruin the door and its ability to swing properly
    4. When you find a door, you may consider adding an inexpensive metal security plate to it, prior to beginning the replacement process
  6.  Once you’ve purchased your replacement pre-hung door, remove the casing or siding around the current door, both inside the house and outside
    1. Take a utility knife around the edges of the casing. This will help release it
    2. Use a flatbar to pry up the casing. Try to do it as gently as possible, so you can reuse it again later
  7.  Remove the original door from its jamb by knocking the hinge pins out of the hinges with a flat bar or flathead screwdriver and hammer
    1. To keep the door from wobbling and falling, stick something underneath it. This could be a t-shirt, a book, a sandal, shims, etc.
    2. When removing the hinges, start at the bottom and work your way up
    3. This job is best done with two people—one holding the door, and the other working on the hinge pins
    4. Once the door is out, set it aside while you remove the jamb
  8.  Remove the door sill with an electric drill
  9.  Assuming the casing is already removed from both sides of the old doorjamb, you are now ready to remove the doorjamb. With a sawzall, cut around the doorjamb to remove it from the wall
    1. You will be cutting through the finishing nails and shims used to hold the jamb in place
    2. Hold the sawzall firmly, as it will want to bounce around
    3. Be careful not to let the saw blade hit the floor. You can cut upward from the bottom of the jamb to avoid hitting the floor
  10.  Push the door jamb out of the wall and set it aside
  11.  Check the subsill to see if it’s level and if it’s compatible with your new doorsill
    1. If the subsill is not level- highly likely- level it out with shims or beveled board
    2. On the pre-hung door, measure from the bottom of the sill to the bottom of the door, and check it against your flooring. It must be such that the door can open properly and clear the flooring (carpet, rug, etc). If the door cannot clear the floor, you will have to raise the height of the door by attaching treated wood to the subsill with caulk and screws
    3. Remember that you do not want the jamb to push too tightly against the rough opening, or it will ruin the functionality of your door
    4. Also, consider putting flashing over the subsill to further weatherproof the door. Make sure to wrap it over the subsill (rather than putting it flush with the subsill), or it will not be effective
  12.  Pop the door into the rough opening to make sure it generally fits, and there are no major problems
    1. Put the bottom in first and tilt the rest in
    2. This is a job much easier done with two people
  13.  If there are no problems with the fit, bind the bottom of the pre-hung door’s sill and the top of the subsill with caulk
    1. About 1” from all the edges of the sill and subsill, add a generous bead of caulk. Add a wavy line in the middle, too
    2. Extend the caulk a couple inches up the sides of the rough opening. This will help keep water out
    3. Consider wearing gloves, as caulk is extremely sticky
  14.  Using a level, make the door plumb (exactly vertical)
    1. Also eyeball the reveal between the doorjamb and the rough opening. Do it look approximately even on all sides?
  15.  Place a shim just above the top hinge, in between the jamb and the rough opening. Then place a shim on the other side (horizontally) of the door jamb, ensuring the structure will stay level
    1. The biggest challenge in installing a pre-hung door is making the door plumb and level. Take your time and ensure the job is done right. This is especially important for exterior doors, where leaking can occur if the job’s not done right
    2. Use a hammer to lodge the shims in place
    3. You can continue to adjust the door slightly
  16.  Go to the other side of the door (if you’re outside the house, go inside) and adjust
  17.  Once the door is secure, try opening and closing it
    1. Does it look as though it swings correctly?
    2. Standing outside, when the door is closed, does the door face seal evenly to the weather stripping?
    3. Make adjustments as necessary
    4. When the door looks good, leave it open
  18.  Drill a small hole through both the jamb and shims
  19.  Secure the door by hammering finish nails through the shims and jamb into the wallframe (more specifically the jack stud), leaving the nail protruding about 1”, in case you need to readjust the door
    1. The nails go into the jack stud of your rough opening
  20.  Continue these steps, working your way down the door
    1. Do the hinge side first, then go across to the other side (horizontally) of the door
    2. Make sure the door is plumb each time you insert a shim and add the nail. Remember to check both sides of the door (inside and outside the house)
    3. As a general rule, place shims at three locations on each side of the door and at each corner on the top
    4. Also shim right above and below the lock strike location. This means the handle-side of the door will have four shims
    5. For the top, do the handle-side first, then move to the other side of the door (horizontally)
    6. Do not over-shim the door. Too many shims will cause the jamb to bow, and the door will not shut properly
  21.  If the door is plumb, hammer the nails in all the way, flush with the surface of the jamb
  22.  Cut off any protrusion from the shims, flush with the wall, with a utility knife
  23.  Put a small bead of expansion foam or insulation between the jamb and rough opening
    1. If using expansion foam, let it dry and then cut off the excess with a utility knife
  24.  Put the casing or siding back on around the door, for a finished look
    1. You may be able to use the old casing, if the dimensions of the new door are close enough to those of the old one. Otherwise, install replacement casing