I have a floor joist where the knot in the middle of the span is somewhat coming out. Attached is a picture. Should I be worried and how do I fix it?

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  • 2
    This has been like this for 60 years and this is as loose as that knot's gotten and now you're worried about it???
    – FreeMan
    Commented Nov 28, 2022 at 18:20
  • 3
    No this just happened it wasn’t like this for 60 years. It was like that since yesterday lol. The drywallers put a block to screw the sheet rock into and nailed into the knot Commented Nov 28, 2022 at 19:25
  • 1
    It would be nice to know what is above this. An open floor(where you just walk)/attic will be less of a concern than a bathtub/safe/water bed.
    – crip659
    Commented Nov 28, 2022 at 21:06
  • Open floor and living room Commented Nov 28, 2022 at 21:10

4 Answers 4


It always happens and was a total miss by the framing crew. But, unless you're springy upstairs it's not really a problem. The adjacent joists will assist just fine for normal empty area loads above.

Although, if you have the ability to address it, then even a 2x4 glued and liberally screwed to one side can remedy any perceived weakness. Preferably, the 2x4 should run a minimum of 3-feet out on either side of the knot, hole, notch or weak spot.

  • Ok thank you that’s what I thought I’d do Commented Nov 28, 2022 at 18:12
  • That would be great and should be no future worries for the area above's use.
    – Iggy
    Commented Nov 28, 2022 at 18:15
  • I totally agree: Grab a 2x4 (others said about 6' long, I dk), some screws, a driver and a tube of Liquid Nails and sister that on. Problem solved. Commented Nov 28, 2022 at 19:26
  • 1
    You think the framing crew would avoid using a joist because of that defect after it has already been graded spf #2? Commented Nov 29, 2022 at 2:19

I would not get too excited.

Reason 1: that knot has been allowed for in the grading of the lumber. If #2 framing will do the job as designed, you don't need to repair every little defect in an attempt to make structural select out of #2.

Reason 2: floor joists are part of a system, where loads are shared by many floor joists working together.

If you can't bear to do that, remove or rip open the drywall for access and sister a hunk of lumber beside that area, extending several feet on either side of it. You'll also have to relocate the cables that are presently stapled to it to do that.

Using a steel reinforcing strap/plate is also an option. That might fit below the cables.

  • 1
    The house was built in the 60s and the beams seem a little undersized that’s why I was a little concerned but thanks I’ll just put a 2x4 below to give a little extra stiffness Commented Nov 28, 2022 at 18:13

Don't worry

That knot was always a weak spot, and the drywall screw that separated it has not made it significantly weaker.

You could add cross blocking to the two neighbouring joists, but really this is much ado about nothing.

Cosmetic damage to a piece that will soon be hidden behind drywall, just let it be.


Overall, it's structurally sound due to redundancies built into neighboring joists.

The frustration will arise if you go to step on that spot from above and start hearing a squeak. That is a prime location for nail pops in subfloor or hardwood.

If you have a drywall seam on that joist or close to it then it has a chance of cracking after it's mudded. Is this parallel seem running in an open air space?

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  • The seam is like a few inches over on a block tho. That’s probably fine no? Commented Nov 28, 2022 at 19:25
  • @MrHeatingguy Well the perpendicular seam is directly below the knot. As for the parallel seam; is it blocked for the entire length of the joist? Why would the drywaller have a seam in the middle of open air space like that? See my edit. Also, if no foot traffic nor heavy item storage occurs above this joist then my observation is moot.
    – MonkeyZeus
    Commented Nov 28, 2022 at 19:32
  • Yes it’s blocked the entire way every 16 inches Commented Nov 28, 2022 at 19:35
  • @MrHeatingguy Interesting. It's probably fine but I don't have the experience to back up that assessment. If you still can then sister a 4-6' joist to it.
    – MonkeyZeus
    Commented Nov 28, 2022 at 19:39
  • I'd be back-blocking the drywall else it's going to crack. but the length is wrong for that.
    – Jasen
    Commented Nov 29, 2022 at 21:19

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