How to Extend Fence Height UK: Legal & Practical Guide
To extend the height of a fence you can add a trellis topper, fit fence post extenders, or replace the fence with a taller system — but before any of that, check the law. In England you can generally have a fence up to 2 metres on a normal boundary without planning permission, dropping to 1 metre next to a highway, and crucially that limit includes any trellis or extension you add on top. This guide covers the legal limits first, then the practical ways to gain extra height safely and without falling out with the neighbours.
Can You Extend the Height of a Fence?
Yes — but only up to the permitted height before you need planning permission, and only with your neighbour's agreement if it is a shared boundary. The most common reasons to raise a fence are privacy, security, and screening, and there are several practical ways to do it. The mistake people make is adding height first and checking the rules afterwards: an over-height fence can be subject to enforcement action requiring you to take it back down.
Fence Height Law in the UK
Under permitted development rights in England, a fence, wall or gate can be built up to 2 metres in height on most boundaries without planning permission. Where the fence is adjacent to a highway used by vehicles (or the footpath of such a highway), the limit drops to 1 metre. Height is measured from the natural ground level on the side where the fence stands. Anything above these limits needs a planning application to your local authority.
The point that catches people out: a trellis counts towards the total height. Adding a 0.5m trellis to a 2m fence makes a 2.5m structure that exceeds the limit and requires planning permission. There is a common myth that trellis is exempt — it is not. If in doubt, contact your local planning authority or apply for a Certificate of Lawfulness to confirm your specific situation. Rules also differ in Wales, Scotland and Northern Ireland, and may be stricter in conservation areas or for listed buildings.
Do You Need Planning Permission to Extend a Fence?
If the finished height (including any topper) stays at or below 2 metres on a standard boundary, or 1 metre next to a highway, you generally do not need permission. If extending takes you above those limits, you do. You will also need permission regardless of height if your property has an existing planning condition removing permitted development rights, or sits in a conservation area or other designated location. When unsure, the safe route is a quick check with the local planning authority before you buy materials.
How to Extend Fence Height
Trellis Toppers
Fixing a trellis panel along the top of an existing fence is the simplest method — it adds height and privacy while keeping a lighter, more attractive appearance than solid panels, and lets climbing plants soften the boundary. Remember the trellis counts towards the overall height limit. It suits domestic privacy rather than security, as trellis offers little physical deterrent.
Fence Post Extenders and Extension Arms
Post extenders bolt to your existing fence posts to raise the height, giving you a stronger frame to fix additional panels or trellis to. This is the right approach where you want to add solid height rather than open trellis, but the existing posts and their footings must be sound enough to take the extra leverage — a taller fence catches far more wind.
Replacing with a Taller Fence System
Where you need real height and security rather than just privacy, the better long-term answer is often to replace the fence with a taller system designed for the job. For boundaries where security matters — driveways, rear access, commercial perimeters — steel palisade fencing provides genuine deterrence at heights from 1.8m upwards, far beyond what a trellis topper achieves. See our complete palisade fencing guide for heights and specifications.
Neighbour and Boundary Considerations
If the fence sits on a shared boundary, you need your neighbour's agreement before altering it — the fence may legally be theirs, or jointly owned. Even on your own boundary, a sudden tall fence can cause disputes or a complaint to the council. Talk to neighbours first, keep the structure on your side of the line, and make sure footings and fixings are strong enough for the extra wind load. A well-built taller fence is far less likely to cause problems than a flimsy one that leans or blows down.
When to Switch to Security Fencing
Trellis and post extenders solve privacy. They do not solve security. If the real aim is to stop intruders or protect a commercial site, a domestic fence with a topper is the wrong tool — it is easily climbed or pushed through. At that point, switch to a purpose-made security system such as galvanised steel palisade, which is built to BS 1722 Part 12 and designed to resist climbing and forced entry. Use the planning checker in our palisade guide to confirm the height you are allowed before installing.
Buy Fencing at Rackerman
Rackerman supplies galvanised steel palisade fencing for secure boundaries in 1.8m galvanised palisade fencing and 2.0m galvanised palisade fencing heights and above, hot-dip galvanised for decades of outdoor life, plus fencing and wire mesh for a range of boundary needs. All palisade is supplied as complete run kits or individual components.
Browse galvanised palisade fencing at Rackerman →
Frequently Asked Questions
How do you extend the height of a fence?
You can fit a trellis topper for privacy, bolt post extenders to the existing posts to add solid panels, or replace the fence with a taller system. Whichever method you choose, the finished height must stay within permitted development limits unless you obtain planning permission.
How do you add height to a fence?
The simplest way is to fix trellis or additional panels to extenders bolted onto your existing fence posts. Make sure the posts and footings are strong enough for the extra height and wind load, and keep the total height — including the addition — within the legal limit for your boundary.
What is the maximum height of a garden fence in the UK?
2 metres on a normal boundary without planning permission, or 1 metre where the fence is adjacent to a highway used by vehicles or its footpath. Height is measured from natural ground level on the side the fence stands. Anything taller needs a planning application.
What is the legal height of a garden fence?
Under permitted development in England, up to 2 metres on most boundaries and up to 1 metre next to a highway. These are the heights you can build without applying for planning permission; conservation areas, listed buildings and removed permitted development rights can lower them.
Does trellis count towards fence height?
Yes. Trellis added on top of a fence counts towards the overall height limit, despite a common myth that it doesn't. A 2m fence with a 0.5m trellis is a 2.5m structure that exceeds the 2m limit and would need planning permission. Confirm with your local planning authority if unsure.
Do I need planning permission to make my fence taller?
Only if the finished height exceeds 2 metres on a standard boundary or 1 metre next to a highway, or if your property has removed permitted development rights or is in a conservation area. If you stay within the limits, you generally do not need permission.
Can I extend a fence on a shared boundary?
Only with your neighbour's agreement. The fence may be legally theirs or jointly owned, so altering it without consent can cause a dispute. Talk to your neighbour first, keep any structure on your side of the boundary line, and agree the change before starting work.
What is the best way to make a fence taller for security?
For genuine security, replace the fence with a purpose-made system rather than adding trellis. Galvanised steel palisade fencing, built to BS 1722 Part 12, resists climbing and forced entry at heights from 1.8m upwards — far more effective than a topper on a domestic panel fence.