I have a 2x4 wood rail between two 4x4 wood columns. It looks something like the drawing below:

enter image description here

The 2x4 rail is warping a little bit, so I want to attach a 2x4 under it so that it can straighten the rail. But I don't want to use screws that will be seen from the top of the rail.

What can I do to securely attach a 2x4 under the 2x4 rail without having to drill at the top of the rail? Or is there a better way to straighten the 2x4 rail?

  • In order to do what you're describing you'll have to have a rock solid connection between the new board and the posts. How do you plan to do that? Is the warped board pulling free of the posts itself?
    – isherwood
    Jul 16, 2019 at 17:03

1 Answer 1


You could screw up through the lower 2x4 into the top 2x4, such that the screw heads would be on the bottom of the lower board and not seen from the top.

But I think there's a different question here: Why reinforce the existing board?

When working on problems like this, I first try to determine the root cause of the problem. Did that 2x4 warp because a 2x4 is not sufficient for that purpose? Or did it warp because the original board was poorly selected (it had a big knot, or gnarly grain).

If a 2x4 is indeed sufficient, then why not just replace the original board, instead of trying to "correct" it with a reinforcement?

If a 2x4 is not sufficient, then how about replacing with a correctly-sized piece of lumber instead of reinforcing the existing board?

In other words, reinforcing the existing board would be low on my list of choices.

  • Great insights! And something we all need to take into consideration when fixing or improving things.
    – J Crosby
    Jul 16, 2019 at 14:19
  • 1
    attaching another 2x4 wont really straighten it. it might bend after a while as well.
    – Quoc Vu
    Jul 16, 2019 at 15:54

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