How to Reinforce a Fence Gate to Keep It from Sagging

There are several ways to reinforce a fence gate to keep it from sagging. A section of preassembled fencing can be used as a gate as long as extra reinforcement is used. Here’s how to go about it:

    1. Cut the panel to the correct size for the gate opening.
    1. Rip 2” thick pressure treated lumber to the width of the existing rails (stringers) on the gate.
    1. Lay the gate on a flat surface, and square it up.
    1. Measure the distance between the top and bottom rails.
    1. Cut the boards to length so they are a tight fit between the rails on each end of the gate.
    1. Secure the two vertical framing boards even with each end of gate using corrosion resistant screws.
    1. Measure and cut a diagonal support board to fit snuggly inside the opposing corners of the gate frame.
    1. Screw the diagonal support in place to transfer the weight of the gate to the hinge side and keep the gate from sagging.
    1. Screw the pickets to the diagonal gate support to provide more support strength.
  1. In addition, wide gates can be reinforced using an anti-sag kit consisting of two corner brackets, a steel cable, and a turnbuckle to tighten the cable as needed.

Watch this video to find out more.

Further Information


  1. About your “How to Reinforce a Fence Gate to Keep It from Sagging”, you say that the diagonal brace should transfer weight down to the hinge side. and yet at the end of the video you show the gate swinging in and the diagonal brace is at the top on the hinge side?

    • Brian,
      Good point. For maximum reinforcement against racking, the diagonal brace on a gate should go from the top of the latch side to the bottom of the hinge side so it presses down on the brace to compress it, rather than pulling on the brace against the fasteners. The gate that Danny was demonstrating was small and light enough that the load wouldn’t cause it to pull it loose, but it’s a good idea for larger or wider gates to run the diagonal brace in the other direction.

  2. Cable braces were installed wrong. It’s twisting the gate not lifting the gate.
    Many people are taught wrong as in the video. It’s simple geometry.

  3. I have a 5 foot vinyl gate installed by a contractor and it sags. What to do to keep gate from sagging? Contractor claims that the gates weight causes the sag and there is nothing they can do about it.

  4. I have a fence that has been weakened as a result from this last winters rain. The fence wants to wobble back in forth during windy days. I am considering placing a short post in line with the post about 8 inches behind it, then attaching that to the fence post with a horizontal piece. If there is another way, I would appreciate knowing what would be the suggestion.
    Thank you for your time


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