Two Layers of Fencing - Why and When

Why and when it makes sense

Installing two layers of fencing, one in front of the other, is more common than many people realise. In some cases it is carefully designed and delivers real benefits. In many others it is added later to fix a problem that the original fence was meant to solve but has not.

This blog looks first at the most common reasons why a second fence is added after the event, before covering the situations where two layers of fencing are genuinely the right solution.

When a fence is not doing its job

In most cases a fence is installed for security. When that fence fails to provide the required level of protection, the quickest solution is often to add another fence rather than address the root cause.

Security fencing that is easy to breach

One of the most common examples is triple point palisade fencing. Read our blog on whether Triple Point Palisade is a security fence. Most of the time where this fencing fails, it is because pales have simply been removed. Once a weakness like this is discovered, instead of upgrading the specification or repairing the issue properly, a second fence is often installed in front.

Hopefully lessons have been learned and a better fence is installed. If not, while this may slow access,  it usually means the original problem still exists. The site now has two fences, both of which may still be vulnerable in different ways.

The image above shows where a Triple Point Palisade fence has failed.  To stop access, another Triple Point Palisade fence has been installed behind but unfortunately, the pales have also been removed from that fence, allowing access.  

When privacy becomes a requirement

Another frequent scenario is where a security fence has been installed but privacy is later required. For example, a mesh fence may meet the security brief, but overlooking or visual screening becomes an issue once the site is operational. In recent years mesh security fencing with privacy features has become a popular choice for schools; it creates an environment that feels safe for pupils, prevents distractions from outside the site, and reduces the risk of pupils interacting with people beyond the school grounds.

Instead of installing a combined system such as a mesh fence with privacy panels from the outset, a second fence is installed behind. This is often a close board fence added purely for screening.

Privacy pales can sometimes be retrofitted to mesh fencing, but this can introduce new problems. Increased wind loading and additional weight can cause the fence to fail if it was not designed to carry these forces.  Read our blog on whether you can add timber slats to an existing V mesh Fence.

In the image above a mesh security fence has been installed. The fence cannot provide the strength needed to support retrofitted battens, therefore a new Closeboard fence has been added inside the boundary to provide privacy.

Valid reasons for two layers of fencing

While many examples are reactive, there are situations where installing two fences is sensible and well planned.

New developments alongside existing boundaries

On commercial developments, contractors will often install a new fence in front of an existing boundary fence. This is commonly done to avoid disputes with neighbours or to prevent disturbance to an established boundary line.

Removing the old fence can cause issues with access, responsibility or ownership. Installing a new fence just inside the site boundary allows the development to move forward quickly while keeping neighbours on side.

The example above shows an old wire mesh fence with a new Closeboard fence installed behind it. The contractor did not want to disturb the old fence, therefore the simplest and safest approach was to install a new fence. This does create a gap that often becomes difficult to manage because of foliage and weeds.

High security sites and layered defence

On high security sites, two layers of fencing can form part of a layered defence strategy. This approach is often designed by a security consultant to meet specific risk profiles or fence ratings.

Multiple barriers reduce the speed of an attempted breach and increase detection time. In some cases, the space between the fences is deliberately designed to be wide enough for patrols. Manned security teams can walk the perimeter while being protected by a layer of fencing on both sides.

Controlled access and zoning

Two fences can also be used to create controlled zones. For example, an outer fence may define the site boundary while an inner fence protects sensitive assets such as plant, storage or data infrastructure.

This allows access to be managed more effectively without restricting movement across the whole site.

The downsides of unplanned double fencing

Where two fences are installed without proper planning, they often create more problems than they solve.

The space between fences quickly becomes difficult to maintain. Weeds, brambles and self seeded trees can establish themselves and are almost impossible to deal with safely or effectively.

Rubbish is easily trapped between the fences and remains there, creating an untidy appearance and ongoing maintenance issues. These areas can also provide shelter for vermin, particularly where there is regular waste build up.

From an operational point of view, inspection and repair become more complex and costly when access is restricted.

Final thoughts

Two layers of fencing can be the right solution, but only when they are planned with a clear purpose. When added as a quick fix, they often mask underlying problems such as poor specification, incorrect installation or changing site requirements and can take valuable space.

Before installing a second fence, it is always worth asking whether the original fence could be upgraded, repaired or replaced with a system designed to meet all requirements from the outset.

Done properly, layered fencing improves security and site management. Done reactively, it can create long term maintenance issues and unnecessary cost.