I've installed the new jamb, however the new jamb appears to bow a bit, and goes in quite a bit at the bottom. I haven't screwed it down yet, or shimmed it, I wanted a second set of eyes (and 3rd, 4th, 100th) to make sure I didn't do something wrong.

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Okay, I apologize for the lack of information given here. To expound, my wife locked the door and closed it behind her before checking to make sure she had her keys, and broke the door frame somehow to retrieve her keys.

So, only the strike side really needs to be replaced. I removed the molding and the old jamb, and bought a new kit from Big Box.

Also, the wall is plaster. From what I've read, plaster door jambs and drywall door jambs are different sizes although we measured thickness of old and new jambs @ Big Box, a quick check of width shows 5 1/4" on the old jamb, and 4 1/2" on the new jamb.

Is there any way to use this smaller jamb? I don't think they have larger ones in stock.

  • Is there enough play in it that you can push it flat, or is it wedged in there really tight? It does need to be shimmed though.
    – Comintern
    Apr 17, 2016 at 14:58
  • @Comintern It's wedged pretty tight
    – MDMoore313
    Apr 17, 2016 at 20:37
  • 1
    It's probably just a hair too long then - it looks like forcing it into a smaller space bowed it. There should be just enough play to allow you to shim it straight and plumb.
    – Comintern
    Apr 17, 2016 at 20:42

5 Answers 5


It's the carpenter's responsibility to properly shim and anchor any door jamb. Unless it's a rigid steel commercial unit, it's not designed to be self-supporting.

I usually shim behind each hinge on the hinge side, and at four locations, including the latch position, on the latch side. Use a combination of wedge and flat shims. For an exterior door I usually use 3" gold construction screws behind the weather stripping.


It appears to me you have a brick exterior and a 2x4 wall that gives you a thicker wall.

At the very least, you need a jamb for 2x6 walls. That may be wide enough to fit.

Then follow the instructions for proper installation.



You removed one side of the jamb, and replaced it with new construction. But, there are 2 problems.

  1. the jamb is bowing;
  2. the jamb is not deep enough. The old jambs were 5 1/4" and fit perfectly since you have plaster instead of drywall. The new jams are 4 1/2" since they are assuming drywall.

Those 2 problems are separate and should be treated as such on here.

As for the 2nd problem, take a look here.

For the first, it looks like you need to cut some off the bottom of the new jamb so it isn't so tight. Take a look at this video.

  • One question. Looking at Big Box's website, they have this kit, it was confusing a bit because a bullet point in the description says 'Use this kit to expand your jamb opening', but it's really for filling the remaining gap, correct?
    – MDMoore313
    Apr 18, 2016 at 14:26
  • 1
    @BigHomie, that is what I understand. I'm actually making jamb extensions for interior doors I replaced in my older home. I found this article and this article to be helpful.
    – mikeazo
    Apr 18, 2016 at 14:45

no - the jamb should be level and square, with the jamb being parallel to the door on all four sides. gap should be about 1/8" on the top, hinge side and strike side, and about 1/4" on the bottom.

make sure the sill is dead flat and level first. this is critical for long life. the trick is to mount the hinge side first, then the top, then the strike. you can drive shims, mortar or silicone (as a last resort) underneath the jamb if you have to, but try to avoid it if you can.

mount the door to the jambset first, and then mount the whole thing as an assembly. this is by far the easiest way to do it. when you mount the jamb legs or top to the opening, use nails or screws such that you can adjust the plumbness and straightness of the whole door assembly wherever you need to. its entirely normal to have to adjust all three parts over and over again to get it to be just right.


Jamb is installed poorly. This installation illustration may be helpful to you... https://www.youtube.com/watch?v=ICYwPa5_bFY

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