The short answer
Concrete gravel boards last longest and protect the fence best; timber gravel boards are cheaper and look more natural but rot over time. A gravel board sits at the base of the fence, between the ground and the panel, to keep the panel off wet soil so it does not rot. A concrete gravel board never rots, takes the moisture and ground contact itself, and lasts for decades — and it is cheap and easy to replace if it ever wears. A timber gravel board matches a wooden fence and costs less, but being in contact with the ground it is the first part to decay. For durability, concrete usually wins; for looks on a short or sheltered run, timber appeals.
A gravel board is a simple part with an outsized job: it is the sacrificial layer at the bottom of the fence that keeps the expensive panel clear of the wet ground. The material you choose decides how well, and how long, it does that job.
Concrete vs timber gravel boards
- Concrete boardNever rots, decades of life
- Timber boardCheaper, natural look, rots in time
- Job of the boardKeeps panel off wet ground
- Replace if wornConcrete: rare · Timber: periodic
- Best pairingConcrete board + concrete posts
What a gravel board is for
A gravel board is a board fixed horizontally at the base of a fence, sitting between the soil and the bottom of the panel. Its purpose is to take the punishment of ground contact so the panel does not. Soil, splashing rain and standing water at the base are what rot the bottom of a fence panel first; the gravel board intercepts that moisture and ground contact, holding the panel clear above it.
Because it is doing the dirtiest job in the fence, the gravel board is designed to be the part you replace, not the panel. That principle — sacrifice a cheap, easily swapped board to protect the costly panel — is why every well-built fence should have one, and why the board's material matters.
Rot resistance, lifespan and cost
Here the materials behave very differently.
A concrete gravel board does not rot, is not eaten by insects and is unaffected by ground moisture. It can sit in contact with wet soil for decades without degrading, so it protects the panel reliably for the life of the fence and rarely needs replacing. It costs a little more than a basic timber board and is heavier to handle, but it is still inexpensive relative to the fence as a whole.
A timber gravel board, even pressure-treated, is in the worst possible position for wood: right at the ground line. It will eventually rot, and it is usually the first part of a timber fence to fail. The upside is that it is cheap and easy to source and swap out, and it blends with a wooden fence. To get reasonable life from a timber board, use pressure-treated timber and keep soil from piling against it.
| Factor | Concrete gravel board | Timber gravel board |
|---|---|---|
| Rot resistance | Will not rot | Rots over time, even treated |
| Lifespan | Decades | Shorter — first part to fail |
| Cost | A little higher | Lower |
| Weight/handling | Heavy | Light |
| Look | Grey, utilitarian | Matches timber fence |
| Replacement | Rare | Periodic |
Indicative comparison for UK fence gravel boards; timber lifespan depends on treatment and ground conditions.
Looks, fitting and combinations
On appearance, the timber board wins for a natural, all-wood fence — it matches the panels and is barely noticeable. A concrete board is grey and more obvious at the base, though it is low down and often partly hidden by planting, and it can be painted if its look bothers you.
Fitting differs with the post type. Slotted concrete posts are designed to take a concrete (or timber) gravel board sitting in the bottom of the slot, with the panel stacked above it — a tidy, secure system. With timber posts, gravel boards are usually fixed with brackets or cleats. Concrete boards are heavier and need careful handling, but once in place they are extremely stable.
The most durable common combination is a concrete gravel board with concrete posts and a timber or composite panel on top. This keeps every part that touches the wet ground in concrete, so only the panel — held safely clear of the soil — is timber, dramatically extending the fence's life.
Heights, levels and the jobs a gravel board quietly does
Beyond rot protection, a gravel board does several useful jobs that explain why fitters fit one almost without thinking. It closes the gap at the base of the fence, which stops pets and wildlife getting under the panel and removes a sight line that would otherwise undermine privacy and security low down. It takes up level differences on uneven or sloping ground, so the panel above can sit straight while the board accommodates the fall — on a slope you may use a deeper board, or stack two, on the lower side. And it adds rigidity at the bottom of the run, helping to brace the panels against wind.
Gravel boards come in different heights, commonly around 150mm (6in) but also 300mm (12in) and taller. A deeper board lifts the timber panel further clear of the wettest ground and is a simple way to add a little height to a fence without buying taller panels — useful where you want to nudge a 6ft fence up towards the permitted limit, or to recover height lost to a raised neighbouring ground level. Because the board is the part designed to sit in the wet, raising the panel on a deeper board protects the timber as well as gaining height.
Fitting follows the post type. With slotted concrete posts, the board drops into the bottom of the channel and the panel stacks on top — quick and very secure. With timber posts, boards are held on cleats or brackets, which makes a timber board easy to unscrew and replace when it eventually rots. Whichever combination you use, the board should sit just clear of, or just into, the soil so that it — and not the panel — is the part meeting the ground.
Which gravel board should you choose?
Decide by weighing durability against looks and budget:
- Choose a concrete gravel board if you want the longest-lasting protection, you are using concrete posts, the fence is in a damp or exposed spot, or you would rather not replace a rotted board every few years.
- Choose a timber gravel board if you want a fully natural wooden look, the budget is tight, the run is short or sheltered, or you are happy to replace the board periodically — and you use pressure-treated timber to slow the rot.
For most permanent UK fences, a concrete gravel board is the sensible default, because it solves the ground-line rot problem outright and almost never needs attention. Where the natural appearance of an all-timber fence matters more, a pressure-treated timber board is a reasonable, cheaper choice, accepting that it is the part you will eventually swap out. Whichever you choose, fitting a gravel board at all is the single lowest-cost step you can take to make the panel above it last.
Frequently asked questions
Do concrete gravel boards last longer than timber ones?
Yes, by a wide margin. Concrete does not rot and can sit against wet ground for decades, so a concrete gravel board rarely needs replacing. A timber board, even pressure-treated, is in the worst spot for wood and is usually the first part of a fence to rot.
What does a gravel board actually do?
It sits at the base of the fence between the soil and the panel, keeping the panel off the wet ground so it does not rot. The board takes the moisture and ground contact itself, acting as a sacrificial layer that is cheaper and easier to replace than the panel above it.
Can I fit a concrete gravel board with timber panels?
Yes, and it is a common, durable combination. Slotted concrete posts hold a concrete gravel board at the base with the timber panel stacked above. This keeps the rot-prone ground-contact part in concrete while preserving the look of a wooden fence.
Sources & further reading
- Jacksons Fencing — gravel boards explained
- Checkatrade — fencing cost guide
- MyJobQuote — cost of fencing
Figures on this page are typical UK ranges drawn from published sources and depend on your specific garden. They are guidance, not a quotation.