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Problem-free Prefit Doors

I’ve been hanging doors for over thirty-five years, and writing about it for nearly twenty-five. For many years, I approached door installs differently every time (like most carpenters). After all, there are so many steps, and there is a lot you need to watch for! It’s tough to do it the same way every time. But a door is a door is a door. Which means unless you’re doing exactly the same thing every time you install one, you’re wasting valuable energy and time.

In this article, I’ll break down door installation into the most important steps—the first five fasteners. But always prepare the opening before you attempt to set the jamb.

Prepare the Opening

Rough openings are exactly that—rough openings—especially today when framers often frame them more than 2 in. over the size of the door. And floors are almost always out of level, too. And walls are frequently cross-legged. Before you attempt to set a jamb, be sure to correct all those problems or they’ll become bigger problems later.

Correct Cross Leg

If you set a jamb into an opening with cross-legged walls, the door won’t lay flat against the jamb and the door stop. You might even think the door is warped, when it isn’t. There are two ways to check for cross-legged walls.

Drive a nail or screw into each corner of the rough opening, then run a string around the four screws, creating an X at the middle of the doorway.

The two strings should touch each other at the X. If they don’t, try to move the walls at the bottom of the opening—just a little.

_MG_1810-1

(Note: Click any image to enlarge)

Use a small sledge hammer and a block of wood, and tap the bottom of each wall lightly. Before banging on a wall, check to be sure there’s no plumbing fixtures or electrical outlets. And look around the back side of the wall for tile, too!

_MG_1808-1 You want to move each wall a little at a time until the strings touch or are close to touching.

Don’t worry about getting it all. You can correct for cross-legged walls when you set the jamb, too.

crossleg2013-1

You can also check for cross-legged walls by cross sighting a jamb. If the jamb isn’t at the end of a narrow hallway, stand to one side of the rough opening and sight across the edge of the jamb nearest you to the opposite edge of the jamb farthest from you.

You’ll need to move your head in order to sight along both edges. Once your head is positioned, look up and down the edge of the nearest jamb. The edge of the farthest jamb should remain parallel. If it doesn’t, the walls are cross-legged; you can see how much the walls must be moved in order to correct the condition. _MG_1817-1

Level the Floor

Don’t wait until the jamb is in the opening to level the floor. It’s too difficult and awkward to hold a level over your head while you’re trying to nail the jamb flush with both sides of the wall. Instead, place a level on the floor and shim it until the bubble is centered in the vial.

_MG_1822-1

If you’re installing the door on a finished floor—like stone, tile, or hardwood—you can measure the thickness of the shim and cut that amount off the opposite leg. If the flooring isn’t installed, leave the shim in place and set the jamb on top of it.

Shim the Rough Opening

Most rough openings are framed too big and must be shimmed in before setting the jamb, otherwise piles of shims must be inserted between the jamb and the framing. Use plywood squares to shim in the rough opening so that the ‘corrected’ rough opening is 1/8 in. wider than the o.d. (outside dimension) of the door and jamb.

If the door is in a hallway or other critical location, be sure to center the corrected rough opening, so that casing and drywall reveals will be equal on both sides of the finished door. _MG_1819-1

But do not shim behind the hinges. Shimming behind the hinges before setting the jamb will prohibit you from making critical adjustments to hinge gaps and will prevent you from making necessary adjustments to strike gaps.

_MG_1820-1 Notice my level has blue tape at each hinge location so that I won’t shim behind the hinges.

Pin the Door in the Opening

Place the jamb in the opening, then remove the fastening screws or temporary latch. Insert two shims at the top of the jamb on opposite sides of the head jamb.

_MG_1823-2

These two shims will safely secure the jamb and the door in the opening.

Adjust the top of the jamb so that it is flush with both sides of the wall—or as close to flush as possible—so that installing the mitered casing will be easier. _MG_1826-1

The First Five Fasteners

Install the first five fasteners in precisely the correct locations and in exactly the right order. Otherwise, you may not be able to adjust the door properly.

5-fasteners-1

In this instructional example, I’m driving screws through pre-drilled counter-sunk holes in the face of the jamb. Instead, drive 15ga finish nails at each location, or drive screws close to the shoulder of the lower rabbet, where the kerf-in weatherstripping will hide the screws.

Fastener #1: Drive fastener one up near the top of the hinge jamb—as high on the jamb as possible. Do not shim behind Fastener #1. Shims are already installed at the top of the jamb. _MG_1829-1
_MG_1834-1 Fastener #2: Drive fastener two up near the top of the strike jamb—as high on the jamb as possible.

Fastener #3: Fastener #3 must be driven at the very bottom of the hinge jamb, as close to the floor as possible. But before driving fastener #3, correct any remaining cross-leg.

Move the bottom of the hinge jamb in or out of the wall until the door is lying flat against the strike jamb. If the jamb is severely cross-legged, don’t try to correct it entirely on the hinge jamb—you can still correct cross-leg before driving fastener #4 (this is especially important with pairs of doors). You may need to insert an additional shim to back up the jamb before driving fastener #3. _MG_1920-1

Fastener #4: Fastener #4 must be driven at the very bottom of the strike jamb, as close to the floor as possible. But before driving fastener #4, correct any remaining cross-leg.

_MG_1833-1 Move the bottom of the strike jamb in or out of the wall until the door is lying perfectly flat against the strike jamb. If you’re installing a pair of doors, be sure that both doors are flush from the top to the bottom before driving fastener #4.

In order to maintain a consistent and acceptable strike gap approximately 1/8 in., you may need to insert an additional shim to back up the jamb before driving fastener #4.

Fastener #5:  This last fastener corrects a serious issue with prefit doors—especially heavy prefit doors. The weight of a door will pull down on the top hinge, placing the top hinge under tension.

That tension will increase the hinge gap above the top hinge. If the hinge gap above the top hinge is not corrected, it maybe not be possible to correct the strike gap and the door may rub against the strike jamb. _MG_1836-1

To relieve the tension on the top hinge and jamb, replace one of the top hinge screws with a screw long enough to penetrate the jamb and the wall framing. Do not torque this screw too much or the door will be jamb bound. A slight amount of pressure on that screw will correct the top hinge gap.

_MG_1831-1 _MG_1837-1

And in the future, that screw can be loosened or tightened to correct the fit of the door in the event the home settles.

Correct the Bottom Hinge Gap

Most heavy doors will apply pressure and compress the bottom hinge, which will close the hinge gap beneath the bottom hinge. Frequently, prefit doors are not installed correctly and the bottom of the door touches the jamb, leading to the door being jamb bound.

_MG_1842-1 _MG_1843-1

To support the bottom hinge and adjust the bottom hinge gap, install a shim just above the bottom hinge. Insert the shim until the hinge gap is equal at the top and the bottom of the door.

Support the Hinge Jamb

Insert pairs of shims—one from each direction—above and below each hinge, and every 12 in. on center (o.c.).

Drive fasteners below the shims, not through the shims. The shims may have to be adjusted in order to improve the fit of the door. _MG_1930-1

Shim the Strike Side and Head

Insert shims every 12 in. o.c. behind the strike jamb, and shim behind the lockset and dead bolt locations, too. Drive fasteners below the shims, not through the shims. _MG_1922-1

Do not drive fasteners near the lockset or deadbolt locations.

Shim the head jamb so that the head gap is even across the top of the door.

Comments/Discussion

35 Responses to “Problem-free Prefit Doors”

  1. Denny

    Great article. Instead of crossing strings, have you ever used the PLS180 laser by Pacific Laser Systems? I love this tool for both installing doors and checking previous installs to troubleshoot problems. I don’t work for or have anything to do with PLS, other than using this product. I love it. Easy to transport and more accurate than a level.

    Reply
    • Timmy

      Great article Gary. I too have set numerous pre hung doors(solo). I’m pretty much in line with everything you mentioned except pinning the door in place. I have tried that way in the past but find the door can easily come loose and once nearly lost a door to the other side of the wall. I have found pinning between the header and the top of the hinge side jamb will also hold the bottom tight to floor. It takes a little practice not to exert to much pressure and bow the jamb but once pinned I can swing the door open(depending on the weight of the door) and check both sides. This also let’s me shim from both sides right from the get go.

      Reply
      • Gary Katz

        Tim,
        I’ve never had a door slip once I’ve tapped in those hinges, and I’ve hung some pretty big ones. I find that using opposing shims also enables you to center a jamb very nicely. But whatever works for you is the right technique!
        Gary

        Reply
    • Gary Katz

      Denny,
      I don’t think a laser would be the right tool for the job. It’s not often that walls are perfectly plumb, so you’d have to make some very picky adjustments with how the laser is sitting on the floor in order for the laser line to plane out with the wall…and even then, that’s not what you’d really be trying to achieve. Remember, hanging doors is a lot easier than you might think. Walls can be pretty twisted, but all you have to do is move the bottom legs on the jamb until the door sits flat against the stop, so in a way, it really doesn’t have anything to do with the wall. Pretty easy. And low tech.
      Gary

      Reply
  2. Kirby

    Gary,
    I’ve read most of your books and articles and had the pleasure of attending JLC to see and experience how you share your knowledge of the door hangers craft so freely.

    This article is great. I’ve loaded it on my TiC iPad app for future reference.

    The explanation of what, when, and why for resolving cross-leg issues was clear and have me rethinking how I do my door installs to ensure consistency and quality.

    Your new shop looks like you have more than enough room for future growth and productions.

    Thanks for passing along your knowledge. Keep sharing your craft.

    Reply
  3. Paul Chek

    Sounds good for solid jam doors. How do you change the procedure for split jam doors?

    Reply
    • Gary Katz

      Paul,
      There really isn’t much difference for split jamb doors. I’ll do go through all of the first 5 fasteners before installing the jamb on the opposite side of the wall. But I’d be very careful about shimming from that side. The butt-ends of any shims would interfere with installing the opposite jambs.
      Gary

      Reply
  4. Erich Loewen

    Also, if you find loose hinges, correct this before you continue, you can’t hang a door properly if if keeps moving around.

    Reply
    • Gary Katz

      Oh my…I’m sure glad I got it right! If I had known Craig Savage was watching, I might not have published the story at all!

      Reply
  5. Ross P

    I love you Gary. I have learned so many awesome tips from you over the past few years. Thank you so much.

    Reply
  6. Denny

    Gary,

    What you are writing about will work for 95% of what is installed typically. (2/8 or 3/0 x 6/8). I deal with more non-typical installs. With all due respect, if a door is not hung on a correct plane, it isn’t installed correctly. I heard a Super on a job instructing a worker to install an interior door to the wall and then tap the stops to meet the door. When the door was closed it stuck into the room at the top and below the plane of the jamb on the bottom. The super was happy with it because when it closed it “sounded” good because the door hit the stops all at once.

    If a wall is leaning one way, or the wall is twisted, you can move the jambs so the door will hit the stop when it closes, but a door should not fall closed or open. If hung correctly, you should be able to swing a door 8″ from the lock side stop and the door should stay. The company I work for manufactures 8/0x10/0 double doors on a weekly basis. I have found if you pin the top with the wall and try to install by simply moving the bottom jamb legs on a unit of this size, it often doesn’t work well. The size of the opening compounds the distance you need to move, especially on double door units. I have found by using the laser (the PLS180 is self leveling) and finding the center point of the plane of the wall, I can move the plane of the frame front to back when I start. (You also can’t install a 8/0x10/0 correctly with the door panels in place simply because of the weight of the unit.) Another reason you need to have a correct plane on a door of this size is the lock. Often this will be a 7 point lock. If the plane on the door unit is not correct, the catches on the lock will not line up with the receiving plates as intended and can cause additional strength to operate the lock and possibly enough stress on the lock mechanism to cause premature failure. I always install to the plane of the door, not the plane of the wall. If I need to correct the wall, I correct the wall. I also point the laser at the hinges/edge of jamb 90 degrees from the wall, and I can see that the jamb and hinges are lined up correctly. To me, installing a 10′ door with a 6 or 8′ level is not as accurate as the laser beam plane. Errors with the installation compound on a door unit of this size. You wrote on another comment that “what works for you is important”. I fully agree! I have found that the laser works for me and I appreciate your thoughts and feedback. Thank you. I enjoy your writing and look forward to your articles. Please keep it up.

    Reply
  7. Lary Graves

    Gary; Thanks for the article; I have often had a difficult time getting the reveal below the bottom hinge to not look pinched. This will make a difference, both in looks and in my time! Looking forward to seeing you in PDX

    Reply
  8. J. Alvis

    This is a great article and has spurred my interest for your videos. I will be picking those up in PDX as well.

    Reply
  9. Mike Rigby

    Hi Gary,
    After plying my trade for over thirty-five years I’m always amazed at new solutions to age old challenges…very clear and concise demonstration…as they say ” grist for the mill”!
    Best, Mike

    Reply
  10. Ed Michnick

    Great article Gary. Have you ever tried countersinking your screws behind the weatherstrip? No holes to fill especially nice on pre-finished units.

    Reply
    • Gary Katz

      Ed,
      Yes, I often place fasteners behind the weatherstripping–nails or screws, depending on what I’m using. But the screws and their locations for that article were STRICTLY used for the demonstration. We use that same set over and over and over and over, so we have to use screws, and we have to be careful how we drive them, too so that we don’t strip the backing. You probably noticed I didn’t tighten them up much. When I hang most doors, I use a 15ga finish gun and shot 2 1/2 in. nails. But I always place them the same way as I did in the article: 1, 2, 3, & 4, and then fastener #5 is a long screw through the top hinge.
      Gary

      Reply
  11. Tim Uhler

    HI Gary,

    Excellent article and video! As a framer, I am not the best door hanger (obviously!) and always fight the gap being tight below the bottom hinge. I have asked that question so many times and not found an answer.

    Now I do. Thanks again, can’t wait to hang the next door.

    Reply
    • Gary Katz

      The reason you haven’t been able to get an answer is because very few people understand the ‘whole picture’ and that often doesn’t happen until you’ve hung a LOT of doors at the same time, which is rare for most finish carpenters–and NEVER happens if you’re a FRAMER!!!! :) Most carpenters shim behind the hinges immediately–that’s what all the articles tell you to do, too. But it’s not until you’ve installed hundreds of doors, one after another, over and over again (or a pro door hanger bangs you on the head!)–that the light comes on and you realize how installing shims prematurely can prevent you from adjusting the door to fit the jamb correctly. I thank the Shaefer brothers for teaching me–definitely the school of hard knocks. :)
      Gary

      Reply
  12. Nathan

    Thank you Gary for a very informative article. I am a beginner home remodeler and while I do not install many doors I sometimes have to adjust doors in the homes that we work on. At the end of the video Gary shows how to adjust the hinge side gap at the bottom by placing the shim above the bottom hinge. How would one go about adjusting that gap if the door is already installed, trimmed, and painted? Thank you again for the articles.

    Nathan

    Reply
    • Gary Katz

      I don’t know of any way to make that adjustment if the door is already installed, not without removing the trim, fastening the bottom of the jamb to the trimmer/jack stud securely, and then shimming above the bottom hinge. If you spread the bottom hinge (use a nail set to bend the hinge), you’ll increase the hinge gap below AND above the hinge, which isn’t the fix you need. That’s why this step is so critical and so many installers walk away from prefit doors that are almost pinching the jamb below the bottom hinge. Remember, the top hinge is under tension from the weight of the door; the bottom hinge is under compression. You have to adjust the jamb for BOTH forces.
      Gary

      Reply
  13. Levi

    Great article, I just need some clarification. So after the door is shimmed and all the gaps are perfect then what? Obviously the shims need to be cut and casing installed. So what keeps the shims in place if we don’t put nails into them?? Thanks so much

    Reply
    • Gary Katz

      I always nail beneath the shims, just to hold them in place. Every time I nail through a shim, I need to move it or adjust it. If I nail beneath the shims, they won’t move or fall down between the jamb and the trimmer or jack stud. But I still don’t shim behind the hinges–above them and below them. I know this goes against ‘accepted’ practice, but try it a few hundred times and you’ll find out how nice it works–while you’re installing the door and later, if you ever have to adjust the door.
      Gary

      Reply
  14. Sam Olson

    I love hanging doors! I worked at Interior Door Replacement Co in Mtn. View, CA for ten years. You toured our shop once during that time and it felt like Barry Bonds coming to watch my Little League game.
    I’m surprised to hear you shim above the head jamb, I was taught not to but also never understood why we didn’t do it.
    I would get a huge kick out of being a grunt on your crew, you’re a future hall of famer, no question.

    Reply
    • Gary Katz

      Hey Sam,
      I love hanging doors, too, and making them, and trimming them, and…I also remember visiting Interior Door Replacement years ago, when you were working with a laser measuring device that worked along with a CNC program to cut and fit doors to old irregular openings. Remarkable technology. I was always curious if that product ever gained popular use.

      There’s nothing special about me or the way I hang doors–I didn’t invent the techniques I use, I learned a lot of them from the Shiefer brothers. Royal and Al were production door hangers in S. CA. and were hanging doors before prefits were used, right after WWII and into the 1980s. I was lucky enough to learn from them at the end of their careers. I’ve also learned a lot the hard way–hang enough doors and that tends to happen.
      Gary

      Reply
  15. Ed

    I’m a newbee preparing to hang my first door ever (a heavy 36″ solid core) and this looks to be useful info. I’m rather surprised that you secure the jamb with finishing nails — wouldn’t have thought them stiff enough to stabilize the door over time. Is there any down side to using bigger nails or screws other than ease of hiding them?

    Thanks for taking the trouble.
    Ed

    Reply
    • Gary Katz

      Ed,
      I use whatever is necessary. Most often, like most carpenters, I use 15ga finish nails to secure door jambs, and then long screws in the hinges to secure the door. Notice I’m talking about TWO different things. The jamb and the door.

      Gary

      Reply
  16. Anthony S

    Great article!

    My wife had a handy man install a side door on our garage. Well the door is binding and it leaks a little below the jamb when it rains hard.

    It is a fiberglass door with vinyl cladding on the jamb. I have inspected the door and jamb and they seem to be fine.

    I’m planning on re-installing this door. How can you move an exterior wall a little for fix cross-leg or just focus on the jamb?

    Are they any other suggestions or things to look?

    Thanks,
    Anthony

    Reply
    • Gary Katz

      Anthony,
      Without seeing the door, it’s impossible to guess what the problems might be. But yes, you often can’t move a wall but it’s easy to move the jamb legs at the sill in order to correct cross leg, but if your door is binding, there’s probably more than just a cross leg issue going one. And without seeing it, I can’t tell you why or where it’s binding or how to fix it.

      Gary

      Reply
  17. Mike

    The doors these days are so cheap the hinge crews into the doors are already striped, people sell 1x finger jointed pine jambs with cheap hinges on a 30 lbs mdf or press board door with pine screwing strip at the hinge, and the screws are 3/4 sheet metal screws. I have hung enough doors to claim I know what I am doing, but there comes a point where cheap is just to labor intensive. Give me 5/4 jambs, and a solid wood door please.

    Reply
  18. Deborah

    Hi Gary

    We are considering the need to straighten up a bowed solid brickwork wall, in order to properly fit hinged double doors Into an opening of 1.4m

    The bow is c50mm top to bottom, and Battening out the wall to straighten it up would mean we lose valuable hallway width , and so I am looking for possible ways to avoid doing so, and i came across your helpful article and wondered if your technique would work in our case , to allow a proper fit of 2 hinged doors across this width of span?

    The double doors are internal only , and will access a utility room off of a hallway, so will not need locks etc.

    I would be very grateful for your advice.

    Deborah

    Reply
    • Gary Katz

      I have no idea. I can’t really imagine what you’re doing. You should see if a local builder or carpenter can help you.
      GAry

      Reply
  19. Bob I.

    Hi Gary, thanks for all your tips. I was wondering if you can put fastener #5 in earlier due to the weight of the door. I have found that heavy doors drop up to 3/8 of an inch as soon as you remove the screw holding the door in place at the strike side. When this happens I immediately install the 2 1/2 inch long screw in the top hinge. This brings up the door drop as well as adjust the top hinge gap. Then I proceed to the bottom fasteners. Do you think this might interfere with your process. Thanks Bob

    Reply
  20. Kent

    Gary, thanks for all your awesome instructional videos and DIY posts. I’m getting ready to install an exterior door with a separate matching single sidelight on the strike plate side. My new set up is identical to the configuration currently in the opening (the door frame is attached to the sidelight frame with corrugated fasteners to make them one unit. Should I attach the new door and sidelight before I install or install them separately? I can send you pictures if it would help make sense. Thanks in advance! Kent

    Reply

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