Fencing

1. 1

   Confirm the boundary and height

   Check the title plan, agree the line with the neighbour, and keep to 2 m in a rear garden or 1 m alongside a highway.

2. 2

   Set out the run

   Run a string line and mark every post position, adjusting the end bay rather than shaving each bay.

3. 3

   Dig the post holes

   Dig to a third of the above-ground height, so 600 mm for a 1.8 m fence and 750 mm on exposed sites, roughly 300 mm across.

4. 4

   Set the posts

   Put 100 mm of compacted stone in the base, stand the post, plumb it both ways and concrete it with the collar shaped to shed water.

5. 5

   Fit gravel boards

   Once the concrete has gone off, fit gravel boards so no panel timber touches wet soil.

6. 6

   Hang the panels

   Drop panels into concrete slots or fix them to timber posts with brackets, keeping the tops in a straight line and stepping the fence on a slope.

7. 7

   Cap and treat

   Cap the post tops and treat any cut ends with preservative before you leave site.

• Fences over 1 m next to a highway, or over 2 m elsewhere, need planning permission. ^[1]
• Listed buildings, conservation areas and Article 4 directions can remove these permitted-development rights. ^[1]

• Before sinking a single post, CAT & Genny every hole position (HSE HSG47). Boundary lines are where incoming services run; a CAT alone won't see the plastic gas main running along the fence. Full method in the Safety guide.
• Post depth: 600 mm for 1.8 m fences; 750 mm for exposed sites or 2 m fences. Always set 100 mm of MOT Type 1 in the bottom of the hole for drainage.
• Postcrete: 1 bag per 100×100 mm post in a 200 mm-diameter hole. Use 2 bags on corner posts.
• Set posts 1.83 m centres for standard panels; check actual panel width on delivery, 'six-foot' panels vary ±10 mm.
• Gravel boards keep timber off wet ground, non-negotiable for fence lifespan.
• On clay, dig post holes 100 mm wider than usual and add 100 mm of clean stone at the base, clay holds water and rots posts at the collar.
• On sloping ground, step panels rather than racking them, racked panels rack the posts too and stress the brackets.

A garden fence is a row of cantilevers. Everything that fails, fails at the post, so the post detail is where the money should go.

• Set out the run first with a string line and mark every post position before digging. Adjust the end bay rather than trying to cheat 20 mm into each bay.
• Hole size: roughly 300 mm diameter for a 100 x 100 mm post, 200 mm for a 75 mm post. Depth is one third of the above-ground height as a rule, so 600 mm for a 1.8 m fence, 750 mm on exposed or windy sites.
• Put 100 mm of compacted MOT Type 1 or clean stone in the base of every hole. A post standing in a concrete cup full of water rots at the bottom first.
• Concrete the post with postcrete or a 1:2:4 mix, finishing the collar above ground level and sloped away so water runs off, never dished toward the timber.
• Concrete posts with slotted panels are the longest-lived option in the UK climate and the easiest to repair, because a broken panel slides out without touching the posts.
• Gravel boards keep panel timber off wet soil. Concrete gravel boards are the sensible choice where soil sits against the fence.
• Cap the post tops or use weathered timber posts. Water entering end grain is the single biggest cause of post failure.
• Brace and check plumb in two directions while the concrete goes off, and leave 24 hours before hanging panels or a gate.

• Retaining soil with a fence. A fence panel is not a retaining wall. If soil is higher on one side by more than about 300 mm, build a retaining wall or use a sleeper wall and stand the fence on top of it.
• Racking panels on a slope instead of stepping them. Racking twists the frame and the brackets, and it looks wrong from both gardens.
• Concreting the panel as well as the post. Panels need to be replaceable; concrete only the post.
• Under-depth posts on an exposed boundary. Most storm failures are 450 mm posts that should have been 750 mm.
• Building on the neighbour's side of the line without agreement. Check the title plan, talk to the neighbour, and keep the fence and its concrete inside your own boundary.
• Ignoring the highway rule. Anything over 1 m alongside a road or footway needs permission, and that includes the fence on top of a wall.

• Lap panel fence, timber posts, supplied and installed: around £70 to £110 per linear metre for 1.8 m high.
• Feather-edge or closeboard on concrete posts and gravel boards: around £110 to £170 per metre, and it is the specification that lasts.
• Concrete post and panel upgrade over timber posts: adds roughly £20 to £30 per metre and typically doubles the life of the fence.
• Removal and disposal of an old fence: £15 to £30 per metre, more if posts are concreted in.
• Gates: £250 to £600 for a timber side gate installed, more for hardwood or automated entrance gates.
• Postcrete works out at about 1 bag per intermediate post and 2 per corner or gate post; budget it separately, it adds up on a long run.