Gravel boards are an essential yet often overlooked component of a well-built fencing system. Positioned at the base between fence panels and the ground, they serve as a protective barrier that prevents timber panels from sitting in damp soil. This simple addition dramatically extends the lifespan of your fencing by keeping moisture, rotting vegetation, and ground-dwelling insects away from the panel itself. Whether you are installing a new fence or upgrading an existing one, understanding how to fit gravel boards correctly will save you money and effort. For those working with timber more broadly, our guide to timber construction techniques offers useful background on handling materials for outdoor projects.
What Are Gravel Boards and Why Fit Them?
A gravel board is a long, narrow board fitted horizontally along the bottom of a fence run, sitting between the fence posts and underneath the panels. Its primary purpose is to create a gap between the soil and the base of the panel, preventing it from absorbing moisture from the ground. Without a gravel board, fence panels sit in direct contact with damp earth, accelerating rot and decay even in pressure-treated timber. Over time, the bottom edge softens, splits, and rots away entirely, requiring full replacement years earlier than necessary.
Beyond moisture protection, gravel boards also give a finished, professional look to your fence run. They hide uneven ground levels and prevent soil from spilling through onto neighbouring gardens. They also help with pest control by closing off gaps that animals might exploit. Gravel boards come in two main types: timber and concrete. Timber boards are made from pressure-treated softwood, making them cost-effective and easy to cut with standard saws. Concrete boards are far more durable and rot-proof, although they are heavier and require an angle grinder to cut.
Timber vs Concrete Gravel Boards: How to Choose
Choosing the right gravel board depends on your budget, ground conditions, and the type of fence you are installing.
| Feature | Timber Gravel Board | Concrete Gravel Board |
|---|---|---|
| Weight | Light, easy to handle alone | Heavy, may require two people |
| Durability | Good with treatment, 10-15 years | Excellent, virtually permanent |
| Cutting method | Hand saw or circular saw | Angle grinder with masonry disc |
| Rot resistance | Moderate with preservative | Complete resistance |
| Upfront cost | Lower | Higher but longer lasting |
| Best suited for | Dry sites, DIY installs, temporary fencing | Wet ground, clay soil, permanent runs |
Concrete boards are the better choice for gardens with heavy clay soil or poor drainage as they will not rot, warp, or soften. They provide a stable base that holds fence panels securely for decades. Timber boards are adequate for well-drained sites and are easier for a solo DIYer to handle since they can be cut on site with basic tools. Whichever type you choose, ensure the boards are at least 150mm deep. For more ideas on how fencing fits into the wider garden layout, read our article on furnishing outdoor spaces.
Tools, Materials and Planning Your Installation
Essential tools needed for the job:
- Tape measure, pencil, and spirit level for marking and alignment
- Hand saw or circular saw for cutting timber boards
- Angle grinder with masonry disc for cutting concrete boards
- Electric drill with wood and masonry bits
- Screwdriver or impact driver for fixings
- Hammer, shovel, and post-hole digger if ground adjustments are needed
Materials you will need to purchase:
- Gravel boards cut to length (timber or concrete)
- Gravel board cleats, clips, or metal brackets
- Corrosion-resistant screws in galvanised or stainless steel
- Concrete mix if bedding posts into the ground
- Wood preservative for treating timber boards
- Gravel or hardcore for backfilling around posts
Follow these steps when planning your installation:
- Measure the distance between each pair of fence posts at ground level and write each measurement down
- Decide the height at which the gravel board should sit, typically level with the bottom edge of the panel
- Mark the height on each fence post using a spirit level to ensure a consistent line across the run
- Cut each board to fit the measured gap, subtracting 2-3mm for timber boards to allow easy fitting
- Dry-fit each board in position before final fixing to confirm alignment is correct
If your fence posts are set in concrete, allow the concrete to cure fully before attaching any boards. Our guide to precast concrete foundation construction covers the curing process and mix requirements in helpful detail.
How to Fit Gravel Boards Step by Step
The fixing method depends on your post type, but the general principles remain consistent across all approaches.
Using cleats or clips: Gravel board cleats are metal or plastic brackets that screw onto the face of the fence post, creating a channel into which the board slots. Position the cleat at the marked height, drill pilot holes, and screw it securely in place. For timber posts, use galvanised screws to prevent rust staining. For concrete posts, use masonry anchors or concrete screws. Once cleats are fitted on both sides, slide the gravel board down into the channel and check with a spirit level before fully tightening.
Using timber battens: Screw a treated timber batten to the face of the post at the marked height, then screw the gravel board directly into the batten. This method is quick and allows easy replacement later if a board becomes damaged. It works best with timber posts and timber gravel boards.
Using pre-formed slots: Many concrete fence posts have built-in slots designed to accept concrete gravel boards. Simply slide the board into the slot from above and lower it into position. Ensure it is fully seated and level before placing the fence panel on top. A slightly uneven base will be noticeable from across the garden.
If you are working with timber, it helps to know about common issues that can affect board quality. Our guide to timber defects and how to handle them covers the imperfections you may encounter when selecting boards. The Hedgehog Street initiative also recommends cutting a small 5×5 inch hole at the base of gravel boards to allow hedgehogs and other small wildlife to move freely between gardens, a simple addition worth considering during installation.
Dealing with Slopes and Uneven Ground
Very few gardens are perfectly flat, so you will likely need to handle sloping ground when fitting gravel boards. The neatest solution is to step the fencing and gravel boards, fitting each section at its own level down the slope rather than angling the entire run. Each step corresponds to one fence panel width, with the boards set at a consistent height above ground.
For shallow slopes, you have an alternative option. Instead of stepping, set the gravel board down into the ground slightly on the higher side so the top edge remains level across the run. This closes the small triangular gaps associated with stepped fencing and gives a cleaner line, although it requires digging a shallow trench. When cutting concrete boards to fit around obstacles, use an angle grinder with a masonry disc and wear appropriate protective equipment. For more on working safely, read the HSE guidance on safe materials handling.
Treating, Maintaining and Replacing Gravel Boards
Even pressure-treated timber benefits from an additional coat of wood preservative before installation, particularly on cut ends where the factory treatment barrier has been broken. Apply preservative generously to all faces and pay special attention to the bottom edge. Brands such as Cuprinol, Barrettine, and Sadolin offer clear or coloured preservatives. Water-based products are more environmentally friendly than solvent-based alternatives while providing comparable protection.
Regular maintenance matters. Inspect timber boards annually for signs of rot, fungal growth, or insect damage. Boards softening at the base should be replaced promptly to prevent issues spreading to the fence posts. With proper care, timber gravel boards can last well over a decade. The Woodland Trust’s guidance on caring for outdoor timber offers useful principles that apply equally to fencing components.
Replacing a damaged board is straightforward. For timber boards with screws or cleats, remove the fixings, slide the old board out, and fit the replacement. Check that cleats are still in good condition before reusing them, as clips can rust or crack over time. Replace any damaged fixings with new galvanised or stainless steel versions. For concrete boards slotted into fence posts, remove the panel above, slide the damaged board upward, slot the new one in, and replace the panel. Concrete boards are heavy so enlist a helper. For a broader overview of outdoor materials, our guide to wall materials and their properties covers durability considerations that apply to fencing components as well.
Fitting gravel boards is a simple task that delivers disproportionate benefits. They protect your fence investment, improve boundary appearance, and can support local wildlife through simple additions like hedgehog holes. Whether you choose timber or concrete, measure carefully, fit level, and maintain regularly for a fence that stands strong for years to come.