Spotting Post Rot at the Ground Line - Deal Coastal Guide

A Deal Fencing working-contractor guide

Timber post rot on the Deal coast starts at the ground line, always. Salt-air-laden rainwater collects in the gap between post base and the surrounding soil or concrete collar; the timber wicks it up an inch; the wicked timber never fully dries between rain events; and the rot organism sets in. On the Kingsdown clifftop plots I have seen posts fail this way inside seven years. On Sholden or Great Mongeham inland plots it takes closer to twelve.

The three tests

Visual

Kneel down at the base of the post, brush any leaf-litter or grass away, and look at the timber where it meets the ground. A healthy post has clean, treated-timber grain visible above the ground line and no visible crumbling. A failing post has one or more of: a dark stain-line above the ground meeting a lighter zone below (indicates capillary rot rising), visible crumbling of the timber grain, a soft spongey face on the down-wind side (Deal coast is prevailing easterly, so the eastern face of the post is the failure face).

Touch

Press the timber at the ground line with a thumbnail. Healthy timber resists a thumbnail push. Failing timber gives - you can dent the surface with the pad of your thumb without pushing hard. Very-failing timber crumbles under the touch and comes away as a soft brown or black fibre.

Push

Stand up. Push the post at chest height, hard, in the direction of the fence line. A sound post does not move. A post rotting at the ground line moves a few centimetres - the entire post is now hinging on the failed base. A very-failed post moves further and the flanking panels are the only thing keeping it upright.

What the tests mean together

Visual clean, touch firm, push solid - post is fine, move on. Visual staining, touch spongey, push moves a bit - post is in the failure window, one to three years of remaining life. Visual crumbling, touch gives, push moves noticeably - post is failed and should be replaced this season. Panels flanking a failed post will warp over time as the post tilts.

Coastal upgrade on replacement

Do not replace a rotted timber post with a fresh timber post on the Deal coast. You are buying yourself the same failure in seven to twelve years. Concrete morticed post plus concrete gravel board is the right replacement spec - see concrete post upgrade versus timber.