How to Fence on Rocky or Sloping Ground

Flat, soft ground is a fencing dream. Rocky hillsides and steep slopes are reality for a lot of properties around Orange, Bathurst, and through the Central Tablelands. The granite country east of Orange, the ranges toward Blayney, and the ridges around Mudgee all present challenges that flat-country fencing techniques can't handle. Here's how to deal with them.

FENCING ON ROCKY GROUND

The problem: Star pickets need to be driven into the ground to a minimum depth of 400mm. When you hit solid rock at 200mm, the picket won't go any further, and a shallow picket is a loose picket.

Solution 1: Move the picket. If you hit rock, shift the picket 200-300mm along the fence line and try again. Rocks underground aren't continuous slabs — there are usually softer spots within half a metre. Your fence line might wobble slightly, but a properly driven picket slightly off-line beats a shallow picket exactly on-line.

Solution 2: Pre-drill. For consistently rocky ground, a rock drill or SDS hammer drill with a long masonry bit can pre-drill a pilot hole. Drive the picket into the drilled hole. It's slow but it works on everything short of solid granite.

Solution 3: Rock-seated pickets. Where you genuinely cannot get a picket into the ground, some fencers concrete pickets into rock. Drill a 50mm hole into the rock surface, set the picket in with fast-setting concrete, and brace it until it cures. This is a last resort and slow, but it's solid.

Solution 4: Timber posts in rocky sections. Where star pickets simply won't work, switch to treated timber posts in pre-drilled holes. They're more expensive and slower to install, but they work where steel can't.

STRAINER ASSEMBLIES ON ROCK

Strainer posts need to be set deep — 700mm minimum — and rock makes this difficult. Options:

Drill and blast: On larger properties, a contracted drill rig can bore post holes through rock. Expensive but effective for critical strainer positions.

Surface-mounted strainers: Where you absolutely cannot get below ground, some fencing contractors build above-ground strainer assemblies using rock anchors. The strainer post sits on the rock surface and is braced with cables anchored into the rock with expansion bolts. This is specialised work and not DIY territory.

Relocate the strainer: If your planned strainer position is on solid rock, move it 5-10 metres to a spot where the soil is deeper. A strainer assembly in good soil slightly away from the ideal position is infinitely better than one poorly set in rock.

FENCING ON SLOPES

Slopes create different challenges to rock, though they often come together.

The mesh problem: Mesh is manufactured flat. When you tension it on a slope, it wants to pull up off the ground on the downhill side and bunch up on the uphill side. The steeper the slope, the worse this gets.

Solution: On moderate slopes (up to about 15 degrees), you can step the mesh. At each picket, push the mesh down to ground level and clip it. The mesh forms a gentle undulation between pickets that follows the terrain. Tighter picket spacing (4m instead of 6m) helps because there's less mesh between pickets to misbehave.

On steep slopes (15+ degrees), you may need to cut the mesh at strainer positions and start a new section on the new grade. Each section is tensioned separately so it lies flat against its particular slope.

Picket spacing on slopes: Close it up. Where you might use 6-7m on flat ground, drop to 4-5m on slopes. The mesh needs more support points to follow the terrain, and pickets take more lateral load from the mesh pulling sideways on steep ground.

Picket alignment: Pickets should always be driven vertically (plumb), not perpendicular to the slope. A picket leaning uphill (perpendicular to the slope) has less holding power and looks wrong. Use a spirit level if you need to — vertical is correct.

WATER MANAGEMENT ON SLOPES

Water runs downhill and it runs along fence lines. A fence across a slope will accumulate water on the uphill side during heavy rain, which can undermine pickets, erode soil from around strainer posts, and create bog holes.

Install water gates or drop-down sections at low points where water naturally crosses the fence line. These are short sections of fence (1-2m) that are hinged or removable so water and debris can pass through during floods without taking out the entire fence.

On long slopes, consider a shallow drainage channel on the uphill side of the fence to redirect water before it accumulates.

GULLY AND RIDGE CROSSINGS

Where a fence crosses a gully, put a strainer assembly on each side of the gully and tension separately. The mesh in the gully bottom will be at a different angle to the mesh on the slopes either side, and trying to tension it as one continuous run creates problems.

On ridge tops, the mesh tends to pull up off the ground as it goes over the crest. Extra pegging or a bottom wire helps hold it down. A strainer assembly right on the ridge top is ideal if practical.

MATERIALS FOR DIFFICULT GROUND

Difficult terrain needs better materials, not worse:

• Use our 2.1kg/m heavy pickets — lightweight pickets flex too much on slopes
• Go with 15cm vertical spacing mesh if sheep are involved — slopes create larger gaps at the bottom
• Use heavier barbed wire (1.8mm MT, $125/500m) for top and bottom wires
• Budget for more strainer assemblies — hilly country needs one every 150-200m

Need gear for tough country? We understand Central West terrain. Call 0434 093 077 or visit us at 76 Astill Drive, Orange.