Wood Fence Gate Binds Only in the Wet Season: Temporal Single-Observable Diagnosis

Why this matters

A gate that swings freely all summer but drags, sticks, or refuses to latch once the rains arrive is a seasonal expansion problem, not a hardware failure. The complaint surfaces weeks or months after installation when conditions change, making it easy to misdiagnose or dismiss. Identifying the specific cause - wood panel growth, post rotation under saturated soil, or marginal fastener engagement - determines whether the repair is a one-hour trim job or a post reset.

Confirm the pattern is truly seasonal

Before diagnosing hardware or wood, confirm the timing is tied to wet conditions rather than a one-time event.

Ask the customer:

• Does the gate bind every wet season, or did it start suddenly after a single storm?
• Does it clear on its own after several dry days?
• Has the latching side always been tight, or did it latch easily when first installed?

A gate that binds consistently only when moisture is high and clears when dry is a true seasonal expansion case. A gate that binds after a single storm and stays bound points to post movement or hardware failure rather than reversible wood swelling.

Measure the gap in both conditions

The single most useful diagnostic step is measuring the gap between the gate panel and the latch-side post in both dry and wet conditions.

Dry-season gap standard: wood gates need a minimum of 10 mm (roughly 3/8 inch) clearance on the latch side to accommodate seasonal movement. Many installers leave only 6 mm or less, which is adequate in dry summer conditions but closes out completely when the wood swells.

How to measure:

1. Measure the gap at the top, middle, and bottom of the latch-side stile.
2. Record measurements in dry conditions and again after a multi-day rain event.
3. A gap that closes from 6 mm to 0 mm or goes negative (panel pressing on post) confirms wood expansion as the primary cause.
4. A gap that stays constant but the gate still binds points away from panel expansion and toward post rotation or hinge problem.

Check hinge-side post plumb under wet conditions

Saturated soil can allow a post to rotate slightly, shifting the gate panel toward the latch-side post even when the wood itself has not expanded enough to bind.

Diagnosis steps:

1. Hold a level against the hinge-side post face while the soil is wet.
2. Check for out-of-plumb in the direction the gate swings (toward the latch side).
3. Even 3-5 mm of lean at the top of a 1.2 m post translates directly to reduced clearance at the gate panel.
4. Probe the soil around the post base for saturation - a post set in a low spot or against a drainage flow is at higher risk.

If the post is plumb in dry conditions but measurably out of plumb when wet, the footing depth, footing diameter, or post-to-footing bonding is inadequate for the soil type. This is a footing repair, not a gate adjustment.

Probe hinge fastener engagement

Wood swelling that is marginal in isolation can tip into binding when combined with loose hinge fasteners. As the wood cycles wet-dry, screws that had borderline thread engagement gradually strip out, allowing the hinge leaf to shift and the gate panel to sag or drift toward the post.

Diagnosis steps:

1. Apply upward and outward hand pressure to the free edge of the gate while watching the hinge leaves.
2. Any visible movement at the hinge plate under moderate hand load indicates fastener failure.
3. Remove one screw from each hinge and inspect the hole - a hole that spins freely or accepts the screw with no resistance has stripped.
4. Check whether original fasteners are the correct length for the lumber thickness - undersized screws are a common commissioning error on gatepost applications.

Stripped hinge fasteners in wet-soft wood often hold adequately in summer when the wood is dry and tight, then fail progressively as the wood swells and the load increases.

Repair by cause

Wood panel expansion with adequate gap at install: Trim the latch-side stile by 6-8 mm using a hand plane or circular saw. Re-bevel the edge slightly so any remaining expansion compresses into the bevel rather than into the post.

Insufficient original gap: Same trim procedure, but document the original gap measurement to confirm it was undersized at commissioning. Inform the customer that the standard minimum gap was not left at install.

Post rotation from saturated soil: Reset the post with a larger-diameter footing poured above the frost line. Confirm the post is plumb before concrete sets. Where drainage is the root cause, regrade the area adjacent to the post base to direct water away.

Stripped hinge fasteners: Plug stripped screw holes with hardwood dowel and exterior-grade adhesive, allow full cure, then re-drive new fasteners of the correct length. Where the wood around the hinge is significantly degraded, replace the hinge block section or install a backing plate on the opposite face.

References

• Wood moisture content and dimensional movement: Woodwork Institute Technical Bulletins
• Fence post footing sizing guidelines: local building authority minimum depth and diameter tables
• Hinge fastener specifications: fence hardware manufacturer installation guides (use fastener length at minimum 2.5x the hinge leaf thickness)