How to Hang a Prehung Door

Co-authored by Ryaan Tuttle

Last Updated: December 12, 2021 References

Pre-hung doors are doors that come from the manufacturer installed in a door frame. Pre-hung doors are purchased with the hinges attached to the door and frame, unlike traditional doors that come with no frame and no hinges. Pre-hung doors are easier to install than traditional doors because the door arrives at your location already built into the door frame, eliminating the need for exact measurements to prevent gaps between the door and frame. Follow these steps to hang a pre-hung door.

Part 1

Part 1 of 3:

Mounting the Door

1
Familiarize yourself with the necessary parts. This guide will likely have a few words you're not incredibly familiar with. Here's what you'll find in your prehung door kit:^{[1]
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- Hinges
- Latchbolt and lockset bore (part of the doorknob)
- Latch jamb and head jamb (the frame of the door that supports it)
- Casing (the trim)
- Mortise for strike plate (where the lock goes into the wall)
  - There are a few terms that will also be used that are a part of your house. These are the header (the part of the wall framing above the door), the king stud (the stud in the wall that supports the header), and the trimmer (the stud in the wall that is next to the jamb).
2
Determine if the floor is level where the door will be hung. The pre-hung door will come with long sides on the frame. This will allow you to cut each side of the door frame according to how level the floor is.^{[2]
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- Cut the sides of the door frame if the floor isn't even. If the floor isn't level, one side of the frame will be shorter than the other to fit with the floor. This will not be noticeable after the door is in place.
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3
Make sure the rough opening is plumb. If it's not, install wooden shims between the rough opening and the door frame. A shim is a thin, tapered piece of wood that is used to fill in the gaps in the door frame. Using shims avoids the necessity for rebuilding the door opening to fit the pre-hung door.^{[3]
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Ryaan Tuttle
Home Improvement Specialist
Expert Interview. 18 June 2021.}^{[4]
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- Use shims on the side of the door with the hinges to remove the gaps between the trimmer stud and the door frame. The door should be square. Have another person hold the pre-hung door in place while you install wooden shims where necessary.
- Ensure the door frame is flush with the wall.
- Hammer a few large finish nails into the frame on the hinge side of the door. Make sure the nails go through the frame and into the shims and trimmer.
- Leave part of the nails out, not hammering them all the way into the frame until you are sure the door is plumb.
4
Shim the trimmers. To shim is to wedge a thing into an area for purposes of measuring or centering. Here's what you need to do:
- On the hinge jamb (the upright support of the door by the hinge), measure from the bottom of the jamb to the center of each hinge. On the hinge-side of the trimmer (likely on the left), measure up from the floor and mark the hinge locations.
- Tack the plumb bob to the top of the hinge-side trimmer. Then, measure the gap between the string and the trimmer where each hinge is located. Place overlapping shims where the gap between the two is the smallest.
- Make the shims 1/8" thick (.3 cm), and tack them with a finish nail. Measure the gap between the new shims and the plumb bob string.
- Place overlapping shims at the bottom two hinge locations on either side. Adjust each pair's thickness until the gap between shims and string is the same as the gap of the first pair.
- Nail each pair of shims to the trimmer and cut off the ends with a utility knife; this is so they don't come out past the drywall.
5
Fit the door into the opening. Take the door and lift it into the opening. Then, push the hinge jamb tight against the shims that are tacked to the trimmers. With 8d finish nails in hand, here's how you progress:^{[5]
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- Take an 8d nail and tack it through the face of the hinge-side casing 3" (7.5 cm) below the miter and into the trimmer stud. Using a level against the face of the casing, adjust the jamb until it's plumb.
- If the wall is set correctly and the casing rests flush against it, drive 8d finish nails through it at the other two hinge locations as well.
- If the wall is out of plumb and the casing is not resting correctly against it, shim behind the casing at the hinge locations to make the door plumb.
- Nail through the casing and shims and into the trimmer stud, securing the door. It's also a good idea to get rid of any gaps between the casing and the wall with tapered wooden wedges.

Part 2

Part 2 of 3:

Mounting the Hardware

1
Adjust the reveal. This is the horizontal gap between the head jamb and the top of the door. It needs to be 1/8 to 3/16" (.15-.3 cm) wide and uniform from all angles.^{[6]
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- If you need to, adjust this gap by pushing up the head casing. Drive an 8d nail through the face of the latch-side casing and into the trimmer stud, near the top of the door, to set everything in place.
- Don't forget to check the vertical reveal between the door and jamb on the latch side, too. It should be about as thick as a nickel. Grab the casing and move the jamb by hand to adjust.
- Swing the door open and close to see if its leading edge, the one that rests against the stop, clears the jamb by a consistent 1/8" on all sides.
- Drive finish nails every 16 inches through the latch-side casing and into the trimmer to set the reveal at the appropriate width. Leave the heads sticking out slightly so they can be set and puttied later. Make sure everything is consistent.
2
Anchor the jamb. To keep the jamb where you want it, slip a pair of shims between the main jamb on the latch side and the trimmer, which is near the top of the door opening. When they are just touching the back of the jamb and not adding pressure on it, nail them to the trimmer with more 8d finish nails.^{[7]
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- You'll want to nail additional pairs of shims a few inches above the base of this jamb and above and below the strike plate, too. Without these shims, the jamb could flex, moving out of place.
3
Replace the hinge screw. On the hinge jamb, remove the center screw from the top hinge and instead use a screw that's long enough to drive into the trimmer stud at least 1 inch.^{[8]
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Ryaan Tuttle
Home Improvement Specialist
Expert Interview. 18 June 2021.} This will keep the door from sagging and binding.^{[9]
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- If the long screws don't match the ones that came with the hinges and door, you can install them behind the hinge leaf so they're not visible.
4
Attach the split jamb. On the outside of your door, there will be a split jamb – it's the one in two pieces. To attach it, start at the bottom and carefully push the edge of it into the groove of the main jamb. With both hands, tap the two pieces together.^{[10]
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- Nail the door casing to the wall on both sides of each miter, in addition to every 18 inches along the casing.^{[11]
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  Ryaan Tuttle
  Home Improvement Specialist
  Expert Interview. 18 June 2021.}
- Once they're together, you'll want them to stay that way. Drive more 8d finish nails through the stop and into the trimmers. You'll need one nail at each hinge location, one through the shims near the top and bottom of the latch jamb, and one just above and below the striker.
- Be sure not to nail into the head jamb.
5
Mount the latch hardware. The door is up – now all that's left is the small hardware additions. To assemble the latch:
- Fasten the strike plate to the mortise in the latch jamb with the screws provided in your kit. If the plate is bigger than the mortise, put the plate on the jamb, outline it, and chisel it to the shape of the outline.
- Slip the latch bolt into its bore and fasten the plate into the mortise on the door's edge with the appropriate screws. If the mortise is too tight, adjust its size just like you did the strike plate.
- Fit the doorknobs to both sides of the latch bolt. Once you're done with that, insert and tighten the connecting screws that hold the knobs together. Test out the knobs and make sure they're secure.
- Close the door and listen for it to latch. If the door rattles, bend the prong on the strike plate just a little toward the stop. If the latch doesn't catch this time, bend the prong away from the stop. Once you find the right arrangement, tighten all the screws.

Part 3

Part 3 of 3:

Finishing Your Work

1
Evaluate your progress. Step away from the door to look at it, measure it and determine if it's plumb all the way around the frame. There should be a 1/8" (.32 cm) opening all the way around the door frame.
2
Use putty to hide the nail heads on the door frame. To make your door look sleek and like it was installed by a professional, hide the nail heads with putty. It is commercially available in many shades – you should be able to find one that matches your door.
- Once applied, smooth it out with a scraper or the blunt edge of a knife. It should be in line with the door and not bulge out.
3
Paint or finish as desired. Now that your door is up and installed, the rest is merely aesthetic. Paint or finish the door however you like – just be sure to use tape around the casing and jambs.

Expert Q&A

Question

Where do you shim a prehung door?

Ryaan Tuttle
Home Improvement Specialist
Ryaan Tuttle is a Home Improvement Specialist and the CEO of Best Handyman, Inc. in Boston, Massachusetts. With over 17 years of experience, he specializes in building home service businesses, focusing on creating scalable and efficient brands. With the help of his global team, the companies have achieved over 10+ million in sales and received recognition through magazine features, and enjoy partnerships with wikiHow and Jobber field service software. Boston Magazine and LocalBest.com have named Best Handyman Boston the Best Handyman in Boston. Ryaan holds Construction Supervisor and Home Improvement Contractor Licenses.

Ryaan Tuttle

Home Improvement Specialist

Expert Answer

Shim the top parts of the door, along with the bottom parts of the door on each bottom side. Then, you'll shim the middle.
Question

How do you screw a prehung door?

Ryaan Tuttle
Home Improvement Specialist
Ryaan Tuttle is a Home Improvement Specialist and the CEO of Best Handyman, Inc. in Boston, Massachusetts. With over 17 years of experience, he specializes in building home service businesses, focusing on creating scalable and efficient brands. With the help of his global team, the companies have achieved over 10+ million in sales and received recognition through magazine features, and enjoy partnerships with wikiHow and Jobber field service software. Boston Magazine and LocalBest.com have named Best Handyman Boston the Best Handyman in Boston. Ryaan holds Construction Supervisor and Home Improvement Contractor Licenses.

Ryaan Tuttle

Home Improvement Specialist

Expert Answer

Screw the doorframe into the framing through where the hinges would be. Just keep in mind that you won't be able to see the hinges!
Question

I installed a new door, it's sticking out on the top corner of the latch side, how do I fix that?

Community Answer

If it's plumb, you can build out the wall, or plane the corner down, or sand or plane the back of the door trim to conform to the wall.