Stabilise loose panels and heavy gates first
Stop work if a fence could fall onto people, vehicles or a public area. Check for buried services before digging around posts.
MOST LIKELY CAUSES
Start with posts, fixings and alignment
Loose hinge fixings
The gate drops away from the post.
Weak or failed bracing
The frame twists out of square.
Moving gate post
The whole hinge side leans.
Oversized or heavy gate
Hardware is overloaded.
Symptom variations Match the movement, lean or latching pattern. ⌄
- Latch side drags
- Top gap is uneven
- Gate needs lifting to close
- Hinges pull away
- Frame appears diamond-shaped
Quick checks Safe checks before dismantling the fence or gate. ⌄
- Check the hinge post for movement.
- Tighten and inspect hinge fixings.
- Measure gate diagonals.
- Check the direction of diagonal bracing.
- Inspect frame joints for separation.
Important:
Correct failed posts and structure before adjusting panels, hinges or latches.
Step 1 — Secure the hinge post Make the smallest safe correction and retest. ⌄
A sound post is essential before adjustment.
Step 2 — Repair hinges and frame Make the smallest safe correction and retest. ⌄
Replace weak fixings and restore squareness.
Step 3 — Add or correct diagonal support Make the smallest safe correction and retest. ⌄
Brace from the lower hinge side toward the upper latch side.
Why the problem happens How wind, weight, moisture and fixings affect the structure. ⌄
The gate’s weight pulls the latch corner downward. Good hinges and diagonal bracing resist that force.
Advanced checks Further diagnosis for persistent outdoor faults. ⌄
- Check hinge capacity.
- Assess gate weight.
- Inspect mortise-and-tenon or screwed joints.
- Check post plumb.
- Consider an anti-sag cable only as a suitable secondary measure.
Tools and information needed Useful items for accurate checks. ⌄
- Spirit level
- Tape measure
- Drill
- Spanners
- Temporary support
Parts that may need replacing Common fencing and gate components linked to this fault. ⌄
- Heavy-duty hinges
- Exterior bolts
- Diagonal brace
- Anti-sag kit
- Replacement post
When to call a professional Conditions that should end basic DIY diagnosis. ⌄
- The gate is very heavy.
- The post is cracked or rotten.
- The gate opens onto a road.
- Welding is required.
- The gate forms part of security access.
Frequently asked questions Common fence and gate questions. ⌄
Which way should the brace run?
From the lower hinge corner to the upper latch corner.
Can I fix sag by moving the latch?
That hides the symptom but does not repair the structure.
Why does the post matter?
A moving post makes every hinge adjustment temporary.