Gravel boards and trellis toppers.
One keeps your fence out of the mud. The other buys height without buying a taller fence.Also sold as Gravel board, Trellis topper, Fence extension.
A gravel board is the sacrificial strip at the bottom of a fence that takes the ground contact so the panel above never touches soil. A trellis topper adds 300–600mm of height and planting to an existing run. Concrete gravel boards add roughly £15–£25 per metre; trellis toppers around £45 per metre, both fitted as part of a fencing job.
Every run is fitted by our own team — see how a fence installation in London works end to end, or what's involved in a full fence replacement.
- Gravel board
- £15–£25/m
- Trellis topper
- From £45/m
- Height limit
- 2m total
Concrete, fitted
300–600mm of height
Trellis counts toward it
The gravel board is not optional
Soil, leaf litter and splash-back hold moisture against timber permanently. Whatever touches the ground rots first — so the job of a gravel board is to be the thing that touches the ground, and to be replaceable when it eventually goes.
Concrete gravel boards never rot, so in practice they are a one-time cost. Timber gravel boards are cheaper and will need swapping in roughly a decade. On a fence you intend to keep, concrete is the honest recommendation.
They also let you level a run over uneven ground. Stepping the boards down a slope keeps the fence line straight when the ground is not.
Trellis toppers and the 2m rule
A trellis topper adds height and softness without the visual weight of a taller solid fence, and it gives climbers something to hold. It is the cheapest way to make a boundary feel private without turning your garden into a box.
One thing to know before you order: permitted development in England caps a boundary fence at 2m total, and a trellis topper counts toward that height. A 1.8m fence with 600mm of trellis is 2.4m and needs planning permission. We flag this on the estimate rather than after it is built — our guide to the 2026 fence rules covers the detail.
What we fit and what we do not
Gravel boards, trellis toppers, post caps and matching gates are all fencing work and we fit them alongside a run. What we do not do is planting, landscaping or garden maintenance — we build boundaries.
- Any fence on soil, which is nearly all of them
- Levelling a run across sloping ground
- Adding privacy without a solid 2m wall
- Standalone jobs — these are fitted with a fence run
- Getting above 2m without planning permission
Questions we get asked
Compare it with
Gravel boards & trellis across London & the South East
Send photos, get an estimateFree estimate · no obligation. Fixed-price survey later only if you want one, from £30 and credited in full against the job.