What is a gravel board and do I need one?

The job is simple and unglamorous. Soil holds moisture against timber, and timber in permanent contact with wet soil rots regardless of how it was treated. A gravel board takes that contact, sits between the ground and the panel, and is designed to be sacrificial or, in concrete, effectively permanent. It also takes the knocks from strimmers, mowers and heaped borders that would otherwise chew the bottom of your boards.

Manufacturers are unusually blunt about this. Jacksons Fencing require gravel boards wherever a fence is in direct contact with the ground or likely to become so, and make it a condition of their 25-year timber guarantee rather than a recommendation. Forest Garden require a pressure-treated gravel board under any dip-treated panel, because dip-treated timber is not rated for ground contact at all. When the people selling the timber write that into the warranty, it is not an upsell.

The economics are lopsided in your favour. A gravel board costs a small fraction of the panel above it, and it protects the exact part of the fence that fails first. Leaving one out saves a little on installation day and shortens the life of every panel in the run. It is the single clearest example on a fencing quote of a cheap component doing expensive work.

One local note. On the clay through the Severn Vale, and on the low ground around Tewkesbury where the water table sits high all winter, we specify concrete gravel boards as standard rather than timber. Ground that stays wet for months will eventually take a timber gravel board too, and swapping a concrete board for timber to save a few pounds on that ground is a false economy we would rather talk you out of.

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