How can I straighten and strengthen this joint?

I can remove the screws holding them together if needed, but that's pretty much all I can do.

enter image description here

2 Answers 2


That railing is probably fastened to posts on both to the left and right of your picture.

  1. One scheme to shore up the existing railing would be to come up from underneath the existing railing with a new wood piece that is the same dimensions as the existing one and screw it up into the existing rail. If the new piece is straight it will push up the sagging joint. Make sure to run the new piece from post to post for best looks and maximal strength.
  2. Another idea would be to cut out the existing rail back to the center of each post on the left and right. Then lay in a new rail piece that is spliced in over the existing posts.
  3. The last and likely not the most feasible idea would be to install an additional post just under the joint. Make the added post high enough that it pushes the sagging joint up to the position it should be in.

I have to say that whoever installed that railing in the first place with a splice like that mid span between supporting posts did not do a quality job. A splice should normally always be over a supporting post of be part of a double or triple beam made up of pieces of lumber with all splices offsetted a good distance from each other.

  • Thanks. I'm considering your suggestion of just removing the wood between the two posts and install a single piece of wood.
    – rbhat
    Nov 18, 2018 at 19:02
  • I'm also considering what BillWeckel mentioned of using galvanized straps. The problem is I don't what straps will be able to straighten that.
    – rbhat
    Nov 18, 2018 at 19:03
  • @rbhad - In my take on the situation trying to use straps or a short metal bar to repair this is a hack at best. The correct way to fix this is to replace from post to post or to sister a new rail under the current one also from post to post.
    – Michael Karas
    Nov 18, 2018 at 20:34

That should've never been mitered there. All miters should be on top of a support post...

If you're looking for a quick and inexpensive fix, cut a piece of pressure treated 2x4 about 24" long and attach it to the underside of your 2x4.

Another option is a couple of galvanized straps screwed to the underside of the miter, both opposing edges, or on all 4 sides if need be. Galvanized strap example

Last option, replace that piece of 2x4. Cut at center of supports on left and right and reattach your new 2x4.

  • Thanks. What are galvanized straps?
    – rbhat
    Nov 18, 2018 at 18:59
  • Edited my answer to include a pic of an example strap
    – BillWeckel
    Nov 18, 2018 at 19:12
  • I had bought a 1/8" aluminum flat bar, but didn't use it because it bent. Is this strap more rigid?
    – rbhat
    Nov 18, 2018 at 19:50
  • Yes, this will be more rigid. You'll probably get better results attaching to the 1-1/2" sides of the 2x4 instead of the top and bottom. Bear in mind too, that this method wouldn't be the preferred method. Best bet is to replace the 2x4 from post to post.
    – BillWeckel
    Nov 18, 2018 at 19:53

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