Spotting fence post rot before the whole run comes down

Why post rot is the fence killer here

Post rot is where most Sandwich fences actually die. Panels come off in gales, boards go bleached and split - those are visible failures. Post rot is quieter. It happens six inches below ground where you can't see it, until one wet October the whole post gives up and the fence leans.

The reason is our water table. The Stour valley and Sandwich marsh sit on heavy alluvial clay with a shallow water table. Post-holes hold water. The wet-dry line on a timber post - roughly six inches below ground - cycles wet then dry then wet then dry with every rainy week, and that cycle is what rots the timber from the inside out. On the Sandwich Bay side, add wind loading, and the compromised post base is what snaps in the gust.

The five signs

1. The lean

Sight along the top of the fence. If the top rail is drifting off level between one post and the next, that post is either loose in its concrete (bad) or is losing its base (worse). Small lean is often just the concrete plug settling, which is fine for a while. A lean that increased in the last six months is a decision point.

2. The wobble

Grip the post at chest height and rock it hard. A sound post moves 1-2mm at the top and returns. A rotted-base post moves 20-40mm and stays leaned when you let go. Second one - book a repair.

3. The screwdriver push

At the ground line on the outside of the post, push a screwdriver into the timber, angled slightly downward. Sound timber pushes 0-2mm and stops hard. Rotted timber accepts the screwdriver up to the handle and comes out with damp dark shavings on the shaft. That post has months, not years.

4. The base look

Dig away 100mm of soil from around the post base on the outside. Sound concrete plug shows clean, grey, with the post seated square in it. Rotted post shows the post has withdrawn from the concrete slightly - there is a visible gap where the timber has shrunk and the plug is now oversized. That gap is where water is entering and where the rot is happening.

5. The mushroom clue

Fruiting bodies on or near the post base - small orange or brown bracket fungi, usually within 200mm of the ground - are a confirmation that the internal decay is well advanced. If you can see fungi, the post is on its last winter.

What each stage costs to fix

• Lean only, sound base - reseat with additional concrete mix, £60-£100.
• Concrete spur repair on early-stage rot - cut post above the rot, bolt a concrete spur onto the sound section, £90-£150 per post. Buys 5-10 years.
• Full post replacement (timber to concrete) - post out, hole widened, new concrete post concreted in, panels rehung. £150-£220 per post. Best long-term answer, and once done it is done.

Timing the fix

The right time to do a post replacement is May to September. The ground is workable, the concrete cures reliably, and there is no wet season pressure on the new plug. The wrong time is December to February - post-holes fill with groundwater and the concrete cure is a fight. If you're seeing the signs above in autumn, book for the following spring; if you're seeing them in spring, don't wait.

What we do on a post-rot walk

Free within 10 miles of Sandwich. We walk the run, do the screwdriver test on every post, and hand you a written list of which posts are sound, which want spur repairs, and which want full replacement. No sell - we tell you the answer that costs least over the next ten years, even when that answer is "leave it another winter and see."