Dos & Don'ts

Fences

A fence stands or falls on its posts — and occasionally on the relationship with your neighbour. The rules that decide both, in plain language. For the full build sequence, see the step-by-step fence guide.

Post depthConcrete vs spikesBoundariesGatesGlass rails

Posts & Foundations

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Dig below frost depth

Set posts below the local frost depth — typically 700–900 mm in frost climates, and at least ⅓ of the post length. Gravel in the hole base gives water somewhere to go.
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Don't set posts shallow

Shallow posts are the #1 fence killer: frost lifts them a little every winter until the fence leans, then falls. Redoing posts later means rebuilding the whole fence.
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Pick the right foundation for the job

Concrete for fences over 1,200 mm, for gates and for windy sites. Steel spikes are fine for low, light fences in firm soil — and the post never touches soil, so it can't rot at the base.
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Don't concrete the post bottom in

Pouring concrete under the post seals the end grain in a cup that holds water. Post sits on gravel, concrete around it, surface tapered to shed water away from the timber.
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Use UC4 (ground-contact) treated posts

Everything that touches soil or concrete must be ground-contact rated. Seal every cut end with end-grain preservative — a saw cut through treated timber exposes untreated wood.
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Don't use interior or UC3 timber in the ground

It rots at soil level in 5–10 years, invisibly, and the fence fails at the exact point you can't inspect.

Neighbours & Rules

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Confirm the boundary and talk first

Check the title plan / land registry before digging, keep the fence on your side (or agree in writing to share the line), and tell your neighbour what's coming. A 10-minute chat prevents a 10-year dispute.
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Don't guess the property line

A fence a hand's width onto the neighbour's land can legally have to come down — after it's built and paid for. Height limits near roads and boundaries also vary by municipality; check before you build, not after a complaint.
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Brace gate posts properly

A gate hangs its whole weight on one post, twisting it constantly. Give gate posts a bigger section (min 100×100 mm), a deeper and wider footing, and ideally a diagonal brace or a paired post.
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Don't hang a gate on a standard post

The most common fence repair is a leaning gate post six months in. It is far cheaper to over-build it on day one.

Fences as Fall Protection & Glass

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Treat guard fences as safety builds

A fence at the top of a retaining wall, slope or terrace edge is a guard, not a garden fence: at least ~1.0 m high, vertical infill with gaps under ~100 mm, posts anchored to take a real impact.
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Don't use climbable designs at a drop

Horizontal boards, rope or wire infill make a ladder exactly where a child shouldn't climb. Most building rules reject them as fall protection — save the horizontal look for the flat garden boundary.
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Use certified safety glass in real clamps

Glass rails use laminated, certified safety glass sized by the manufacturer, held in the manufacturer's clamps or channel, with a top rail. Buy the panel and fixing as a system.
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Don't improvise with glass

Window glass, unknown second-hand panes or home-made fixings can shatter or let go as one piece. Broken glass at a drop is a double accident.
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When to call a professional: any fence or railing whose job is to stop a fall of roughly 500 mm or more — get the design and fixing verified by a qualified builder. Also call for help when the line crosses unknown buried services, on steep slopes and retaining walls, or when the neighbour dispute is already warm: a surveyor is cheaper than a lawyer.
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Ordinary garden fences on flat ground are a safe and satisfying DIY job. It's the drops, gates and boundaries that deserve extra respect.

Draw Your Fence, Count Every Post

Trace your boundary in the Home Planner — posts, boards, concrete bags and screws are counted from the actual drawn line, corners included.

Open the Home PlannerFence Calculator

Frequently asked questions

Why do fence posts lean after a few winters?

Almost always frost heave from posts set too shallow, or water collecting in the post hole. Set posts below local frost depth with gravel in the base of the hole, and taper the concrete to shed water.

Concrete or steel spikes for fence posts?

Concrete for fences over 1.2 m, gates and windy sites. Steel spikes suit low, light fences in firm soil — and keep the post out of soil contact so it can’t rot at the base.

Can I build a fence on the boundary line?

Rules vary. Confirm the legal boundary from the title plan first, and either keep the fence on your own side or make a written agreement with your neighbour. A fence that encroaches can legally have to be removed.

Can any fence act as fall protection?

No. A fence guarding a drop of roughly 0.5 m or more is a guard rail: at least ~1.0 m high, non-climbable infill with gaps under ~100 mm, and impact-rated fixing. Have it verified by a qualified builder.

Boundary rules, height limits and guard requirements vary by country and municipality — the figures here are common EU/US practice, not your local code. Fall-protection fences and railings should be verified by a qualified professional.Last reviewed: July 2026