Installation of a Fence Post Brace up to 2.7m

Tensioned mesh or line wire pulls the posts along the line of the fence. On intermediate posts the pull from both sides cancels out. On end and corner posts it does not, because the force comes from one side only. That is why braces mainly go here:

• End posts: one brace, pointing along the fence line
• Corner posts: two braces, one along each side of the fence
• Gate posts, and places where the fence changes direction or runs onto a slope
• Long straight runs: many manufacturers also specify braces at intermediate straining posts

Why does the brace sit on the mesh side and not behind the post? It works as a prop that pushes the post against the pull of the mesh. On the opposite side, the pull would only try to tear it away. On taller panel fences the brace mainly helps against wind. Solid or dense panels catch a lot of wind.

Everything depends on a post that is solidly concreted and plumb. The brace is fitted after the post, ideally at the same time or shortly afterwards, before the mesh is tensioned.

1. Setting out. The fitter decides at what height the brace meets the post. This is usually in the upper half to upper third of the post, depending on the manufacturer's system. That height determines where the foot of the brace lands in the ground.
2. Angle. The brace should sit at roughly 40 to 50 degrees to the post. A steep brace gives almost no support. A very flat one gets long and can bend.
3. Digging the footing. A hole is dug for a concrete block. For fences of this height a depth of roughly 60 to 80 cm is common, so the footing reaches below the frost line. In colder regions it may need to go deeper. The bottom is compacted and, where needed, a layer of gravel goes in.
4. Fixing to the post. The brace is attached with a clamp or a bolted bracket. The joint must be tight, with no play.
5. Concreting. The footing is filled with concrete, which is rodded or compacted so no voids remain. The top is shaped to fall slightly away from the brace so water runs off.
6. Curing. Until the concrete has set, neither the brace nor the post may move. Tensioning the mesh waits at least a few days, depending on the concrete and the weather.

Braces are usually steel tube or section, hot-dip galvanised, often with a polyester or plastic coating in the fence colour. They should match the diameter and system of the posts, otherwise the clamps do not tighten properly. For taller fences or fences under more load, a heavier-walled section is worth it.

Fixings: clamps, bolts and washers should be galvanised or stainless steel. A plain bolt will rust long before the fence wears out.

Concrete: a general-purpose mix such as C16/20 or C20/25 is typical, or a bagged dry post mix. With post mixes, follow the instructions on the bag, especially for water quantity and setting time.

Protection: anywhere the brace was cut or drilled needs treating with zinc spray or an anti-corrosion paint. An open tube end gets a cap so rainwater cannot run inside.

The simplest case is fitting braces together with the posts on a new fence, in soft ground that digs easily. More work comes with:

• Stony or compacted ground, made-up ground full of rubble, tree roots
• Slopes, where the angle and depth need more careful measuring
• Poor access, for example a narrow strip between the fence and a building, or established planting
• Retrofitting to an old fence, where the mesh has to be slackened and the post straightened first
• Underground services near the boundary, where digging has to be done by hand and with care

On a longer fence the work goes faster, because the holes and concreting are done in one go.

• Shallow footing. A small block just below the surface gets lifted by frost and the brace stops supporting the post.
• Wrong angle. An almost vertical brace cannot hold the post, so the fence slowly leans.
• Brace on the wrong side. It must be on the side the mesh pulls towards.
• Play in the clamp. A little movement grows over time and the brace stops working.
• Voids in the concrete. Concrete tipped in without compacting only looks solid.
• Tensioning too early. Fresh concrete cannot take the pull and the post moves.
• Unprotected cuts. A brace cut to length without treatment starts to rust right at the joint.

If your posts are firmly concreted and plumb, you can fit a brace yourself. Before digging, check that no gas pipe, electric cable or water main runs at that spot. Ask the utility companies or use a cable and pipe locating service. If you damage a gas pipe while digging, move well away at once and call the gas emergency number or 112.

1. Get the brace, clamp, galvanised bolts, concrete, gravel, spade, spirit level, tape measure and wedges or battens for propping ready.
2. Check that the post is plumb and solid.
3. Hold the brace against the post on the mesh side and set an angle of roughly 40 to 50 degrees.
4. Mark the position of the foot and dig a hole about 60 to 80 cm deep.
5. Compact the bottom and add a thin layer of gravel.
6. Fix the brace to the post with the clamp and tighten the bolts until the joint has no play.
7. Check the post for plumb again and prop the brace so it cannot move while you concrete.
8. Fill the footing with concrete, rod it as you go and slope the top away from the brace.
9. Treat cuts and drilled spots with an anti-corrosion product and fit the end cap.
10. Let the concrete cure as the manufacturer recommends before tensioning the mesh.
11. Retighten the clamp once the mesh is tensioned.

• The brace is on the side the mesh pulls towards, with two at each corner
• The angle to the post is roughly 40 to 50 degrees
• The post is still plumb after the mesh is tensioned
• The clamp is tight and the brace does not move in it
• The concrete footing has no cracks or visible voids
• Water drains away from the footing and does not pool at the brace
• Cuts are treated and open ends are capped
• Pushing on the top of the post by hand, the fence does not spring or lean