TL;DR

  • Sagging gates are almost always caused by the hinge-side post moving or the gate frame racking.
  • Fix the post first (reset, sleeve, or replace), then install an anti-sag cable kit to square the frame.
  • Most gate repairs take 30–90 minutes and cost $180–$450 from a pro.
  • If the hinge post is rotted at grade, an anti-sag kit alone won’t hold.
  • Stainless hardware on coastal gates is non-negotiable.

If your fence gate drags on the concrete, won’t latch without lifting it, or has developed a visible gap on the latch side, you’re not alone — it happens to most residential gates within 5 to 10 years. Almost every time, the cause is one of three things and the fix is straightforward.

Why gates sag

The hinge-side of a fence gate carries all the weight. Over time, three things happen:

1. The hinge-side post moves. Concrete cracks or settles. Soil compacts differently on one side. Sandy soil heaves after a wet winter. The post no longer stands plumb, and the gate falls with it.

2. The gate frame racks. A rectangular gate frame, if it has no diagonal bracing, will eventually lose its square. Top-hinge corner drops, bottom-latch corner drags, latch side swings wide of the post.

3. Hinges loosen. Screws strip out of the wood. Hinge plates bend under years of weight. Bushings wear out. The gate drops visibly relative to the post.

Usually it’s some combination. An anti-sag cable kit fixes the racked frame; resetting the post fixes the movement; fresh hinges fix the hardware wear.

Diagnose it in 60 seconds

Stand at the latch side of the gate. Look at three things:

Is the hinge-side post plumb? Hold a 4-foot level against the post. If the bubble’s off, the post has moved. That’s your first fix.

Is the gate frame square? Measure the diagonals of the gate frame — top-hinge corner to bottom-latch corner, then top-latch corner to bottom-hinge corner. If they differ by more than 1/4 inch, the frame is racked. That’s your second fix.

Are the hinge screws tight? Try to wiggle the hinge plate with your fingers. Any play means loose screws or stripped wood. That’s your third fix.

Most sagging gates have two of the three. Tackle them in order: post first, frame second, hinges third.

Fix 1: Reset the hinge-side post

If the post has moved:

Minor lean (under 10 degrees in solid concrete): Brace the post upright with 2x4s and an anti-sag kit on the gate. Install a galvanized post stiffener sleeve (like Simpson Strong-Tie E-Z Mender) at the base of the post, driving it into the ground beside the existing concrete and bolting it to the wood post. This reinforces a post that hasn’t fully failed.

Cracked concrete footing: The concrete needs to come out. Dig around the post base, break the concrete with a mini sledgehammer or a cold chisel, remove, plumb the post with new bracing, pour fresh concrete to 30-inch minimum depth, crown above grade.

Rotted wood post at grade: The post needs to come out. Replace with cedar or pressure-treated 4x4, set in fresh concrete. Or, if the concrete footing is still good, install a steel post sleeve and brace a new shorter wood post into the existing footing.

This fix runs $275–$550 per post from a pro. DIY is possible if you’re comfortable with concrete work.

Fix 2: Install an anti-sag cable kit

The anti-sag kit is the cheapest, highest-impact gate repair you can do. It’s a steel cable strung diagonally across the gate frame, tensioned by a turnbuckle, that pulls the sagging corner back into square.

Parts you need: Galvanized or stainless cable, two cable clamps, a turnbuckle, two corner brackets. Kits are sold at Home Depot or Lowes for $15–$30. Get stainless if you’re coastal.

Installation:

  1. Attach one corner bracket to the top-hinge corner of the gate frame (with screws).
  2. Attach the other corner bracket to the bottom-latch corner.
  3. Run the cable from the top-hinge corner bracket down to the bottom-latch corner bracket, through the turnbuckle in the middle.
  4. Use cable clamps to secure the cable loops.
  5. Tighten the turnbuckle gradually. The gate will visibly square up as tension increases. Stop when the gate is plumb and the latch lines up with the strike.

Total time: 30 to 45 minutes. Total parts cost: $20 to $30.

The kit pulls the saggy corner back into square. It doesn’t fix a moved post (the post still needs to be plumb for this to hold). But on a racked-frame-only sag, this is often the only fix needed.

Fix 3: Fresh hinges

If hinge screws are stripped or hinge plates are bent, replace them:

  • Get stainless or hot-dip galvanized hinges if your gate is outdoors (coastal zones require stainless).
  • Buy one size up from the old hinges — more surface area for new screws to bite into new wood.
  • Use longer screws — go 2.5 to 3 inches into the post if the old 1.5-inch screws stripped out.
  • Pre-drill pilot holes to avoid splitting the post.

Gate hinge replacement is usually $120–$240 from a pro; $20–$60 DIY if you have the tools.

When DIY isn’t going to hold

Call a pro if:

  • The hinge-side post is rotted through at grade. An anti-sag kit loads the post more than the gate — a rotted post will snap.
  • The gate frame is visibly twisted (3D rack, not just 2D racking). May need rebuilt.
  • The concrete footing is cracked and settling. Needs excavation.
  • The gate is a large drive gate with automatic opener. Opener mechanisms store spring or hydraulic energy — DIY can be dangerous.
  • The fence is under HOA-visible scrutiny and the repair needs to look professional.

Pro gate repair typically runs $180–$450 including the fix and any parts. Most are done in 2–4 hours.

Coastal gate notes

Coastal San Diego gates sag faster than inland because the hardware rusts. Once the zinc coating on hinges or screws starts to corrode, the grip weakens and the gate drops.

If your coastal gate is sagging for the second or third time, the fix isn’t another adjustment — it’s replacing all the hardware with stainless. Stainless hinges, stainless lag screws, stainless anti-sag cable, stainless latch. That sequence stops the cycle.

Stainless hardware costs 3–5x what zinc-plated costs. On a single gate rebuild, the extra is $40–$80 in parts. On the life of the gate, it saves 2–3 repair trips.

When the gate should just be replaced

Replace the whole gate instead of repairing if:

  • The gate frame has rotten pieces in multiple spots (not just one corner).
  • Wood is so cracked that new fasteners won’t grip.
  • The gate was never built with bracing or anti-sag provisions and always sagged, even when new.
  • The hinge-side post is fully rotted and the latch-side post is failing too — if both posts are going, a gate rebuild with steel inserts in fresh concrete is often cheaper than trying to salvage pieces.

A new cedar walk gate built to match an existing fence runs $350–$650 installed. A new vinyl gate runs $400–$800. Automatic drive gate replacements with new openers: $3,500–$7,500.

What we do on gate calls

Most gate repairs we handle are same-day or next-morning. We carry anti-sag kits, replacement hinges (stainless and galvanized), and stiffener sleeves on the truck. The diagnostic-and-fix usually takes under 90 minutes on a typical residential gate.

For HOA-visible gates, we coordinate with the HOA if the repair needs approval. Pool gates get priority — a non-compliant pool gate is a real code issue.

Send photos of your gate, including the latch-side gap and the hinge-side post at the ground, and we can usually quote the fix without a site visit.