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How to Fix a Sagging Fence Gate

This Old House general contractor Tom Silva helps a homeowner solve an all-too-common issue: a sagging fence gate.

This Old House General Contractor Tom Silva heads out on a house call to help a homeowner solve an issue with a sagging gate. After excavating, Tom reinforces the gate’s post with some expanding foam. Then, he takes the gate and racks it back into shape before attaching custom-made brackets.

Steps for Fixing a Sagging Fence Gate

  1. Start by assessing the gate. Check to see if only the swinging portion of the gate is sagging, or if the post it’s attached to is also leaning or wobbling.
  2. Use the impact driver or screw gun to remove the gate from the post. For heavy gates, it helps to have an extra hand that will prevent the gate from dropping. Otherwise, prop the gate on blocks of wood or bricks before removing the screws.
  3. If the post is wobbling, you’ll need to start the repair there. Use a shovel or post hole digger to remove the soil from the ground around the post. Check the condition of the post for severe rot. If the post is rotten, remove it and replace it with a new post.
    If the post is only slightly decayed, it may have several years of service left, so determine whether it’s worth replacing or simply shoring it up.
  4. With either the new post in place, or the old post still in the ground, use a level to check for plumb in all directions and steady it in place with a pair of support boards nailed or screwed to the post. Attach the other end of the support boards to a stake driven into the ground.
  5. Break the seal on the expanding foam and mix it back and forth according to the manufacturer’s instructions. Open the bag and pour it into the hole. Allow this foam to set according to the instructions. Once it’s dry, remove the supports and attach the post to the fence, if necessary.
    Note: Temperature and humidity levels can affect the curing time.
  6. Lay the gate on a flat surface. Use the tape measure to take measurements from opposing corners to determine how out-of-square the gate is. Divide the difference of the opposing measurements in half. For example, if one measurement reads 49 inches, while the other measurement reads 47 inches, the gate will be out of square by 1 inch (49-47=2, 2/2=1).
  7. In almost all cases with sagging gates, it will be necessary to lift the bottom of the latch side to square up the gate. Stretch a pipe clamp or ratchet strap across the top corner on the hinge side to the bottom corner on the latch side and tighten slowly until the gate is square.
  8. Using wood corner supports made from pressure-treated lumber, drill and screw a support into each corner. If the rails (the top and bottom board of the gate) and styles (the vertical boards of the gate) overlap, drive two screws through the face of each corner to create more support.
  9. With the post dry and steady and the gate squared, hang the gate from the post and test the swing. It may be necessary to adjust the post on the latch side of the gate as well, and if so, follow the steps outlined above.

Resources

Tom repaired the fence using some basic tools, including a post hole digger, a staple gun, and a drill driver, which can all be found at home centers.

To straighten the fence posts, Tom used Sika Fence Post Mix.


Materials


Tools