Perimeter Intrusion Detection For Warehouses

Your warehouse perimeter is the line between the public and everything you’re responsible for, from the stock on racks to trailers parked up in your yard overnight (often loaded and ready to go).

And for most of the night, nobody’s standing at it, or even watching it.

That’s why warehouse security often starts at your fence, and why perimeter intrusion detection is usually one of the first things you should think about when reviewing your warehouse perimeter security.

But choosing between fence sensors, smart cameras, or even manned guards or patrols isn’t simple.

Choosing between the technologies available is only half the decision you have to make so this guide should make it easier for your to understand how to effectively protect your warehouse perimeter.

How Perimeter Intrusion Detection Works On A Warehouse Site

A perimeter intrusion detection system (PIDS) is a network of sensors around your warehouse’s perimeter that raises an alarm when intruders try to cross it, reducing the risk of theft and vandalism by alerting you sooner to any potential threats.

The National Protective Security Authority (NPSA) describes PIDS as “giving the earliest possible warning of an intrusion attempt”, so a control room can respond early.

It’s not the same as physical barriers and it’s not going to slow anyone down by putting an obstacle in front of them (it works best when you combine it with security fencing or gatehouse security) but it’s an early warning system when someone tries to get on your site who shouldn’t be there.

For a warehouse, we find it helps to think of detection in four layers:

• The boundary fence, your first line of defence and the place to detect cutting or climbing
• The yard and trailer park, including any “sterile zone” (a clear strip between two fences where nobody should be), where detection picks up movement inside the line
• The building shell, meaning the roller shutters, dock doors, fire exits and your roof
• Inside your building, which tells you someone has got through everything else

The Main Types Of Perimeter Detection And Where Each Fits In Your Warehouse

There’s no single best type of perimeter detection.

In our experience, most warehouses end up with a mix.

NPSA groups perimeter detection systems by where they sit (on the barrier, in the ground or free-standing above it).

Fence-Mounted Sensors

Fence-mounted (or “barrier-mounted”) sensors attach to your perimeter fence and pick up vibrations of anyone cutting through or trying to climb over it.

It’s important your sensor matches your fence type because otherwise you’ll end up dealing with dozens of false alarms if your fence is too flexible for a sensitive system and goes off whenever the wind blows, or it won’t go off at all if the fence is too rigid and doesn’t vibrate enough.

Ground-Based Sensors

Ground-based sensors are buried along your perimeter and detect pressure or vibration from footsteps and vehicles.

They’re not going to give you any physical deterrent (because they’re not visible) and they can be expensive because of the work you need to install them underground.

Also, once they’re in, you can’t move them – at least not easily – so they’re usually better on a site where you know the perimeter won’t move for a long time or at least where the ground is easier to dig up.

Video Analytics & Detection-Led CCTV

Video analytics turns your CCTV cameras into detectors, flagging when a person or vehicle crosses a line, or picking up body heat in the dark.

The advantage of these is that the camera raising the alarm also shows an operator what caused it, so detection and verification come from one device rather than having someone try and flick between two things when a security incident has kicked off.

The potential downside is cameras need power and a clear view.

For an unpowered compound or a temporary need (a yard extension, for example), a self-contained VPOD alarm gives you photo-verified detection without needing a mains supply, connected to our National Operations Centre (NOC), where SIA-licensed operatives oversee your system 24/7.

Intruder Detection At Your Building’s Shell

Perimeter detection can buy you time to raise an alarm with the right people (or the emergency services), but you shouldn’t think of it as a replacement for your building’s alarm.

The perimeter detection tells you someone’s on your site when they maybe shouldn’t be, whereas the building alarm tells you they’re trying to get in.

On most warehouses where we do a risk assessment, the weak points tend to be the same.

Roller shutters, dock doors at your loading bays, side doors and fire exits, and the roof and skylights are possible entry points for an intruder.

And each needs its own detection.

That could be guards on doors and exits, detectors or sensors on shutters, beams across loading bays and PIR detectors inside, where they work.

That’s the difference between a perimeter security alarm and a warehouse alarm system.

One watches your boundary, the other protects your building and its contents.

Most sites we work with need both.

We wouldn’t say this is just a peace of mind issue either.

Chances are your insurer is likely to have a view.

Intruder alarms are graded one to four under BS EN 50131, with higher grades for higher-risk premises.

If you don’t know which is right, insurers usually tell you which grade they want.

A police response sets the bar higher again, because the National Police Chiefs’ Council (NPCC) policy says an alarm must be “confirmed” before it qualifies and a newly installed system has to meet PD 6662:2017 and BS 8243 and be installed and maintained by an approved company.

We’d advise checking that any provider can work to those standards, or look at our intruder alarms systems to see how our solutions work.

Why Every Alarm Needs Verifying

No system is infallible, especially when it’s around a warehouse where you’ve got people, wildlife, foliage and weather to deal with. We’ll say now false alarms are inevitable with any system.

If you’re wondering how many false alarms are acceptable for an intrusion detection system, the NPSA says 5 false alarms a day are acceptable for every kilometre of perimeter in good weather, rising in bad weather.

On a warehouse, the usual issues are wind rattling a loose fence panel, vegetation growing into your fence line, foxes and birds, or packaging blown across your yard.

What you need to make sure of is your system remains trusted and doesn’t become a source of annoyance that staff think they can ignore because “it’ll just be another false alarm”.

NPSA recommends setting detection up in zones so an alarm’s location is known straight away, with cameras covering each zone and perimeter lighting so operators can see what’s there.

A monitored control room (like our National Operations Centre) then makes the call on whether it’s a real intruder or nothing to worry about before anyone’s sent to look, which is exactly the job of CCTV monitoring (ours is NSI Gold approved).

What Happens After An Alarm Triggers

It’s sometimes argued or suggested to us on calls that a good enough perimeter system can replace patrols and people on site.

It’s not an unreasonable view, because sensors monitor your whole fence at once and don’t need a shift rota or a break.

What we would say though, is a sensor only tells you something has happened.

It can’t decide whether the alarm is real and it can’t secure your site.

Whether or not your detection system works depends on what happens when it detects something.

Here’s our recommendation for how that should work:

1. A sensor triggers and the alarm comes into the control room (our NOC) with the zone attached.
2. An operator brings up the camera for that zone and checks what caused it.
3. If it’s real, a keyholding or response officer is dispatched, or the police are called where the alarm qualifies for a police response.
4. Your site is checked and secured and you get a report of what happened and what was done about it.

Our alarm response officers can cover you on the last bit when they’re brought in alongside intrusion detection.

In practice, not having that physical presence sitting alongside your alarms means you’re in a position where you find out faster that someone is trying to get on to your site, but you can’t react quickly enough to do anything about it.

Choosing The Right Combination For Your Warehouse

Picking the right security depends on what’s going on on your site and where the risks are coming from, so it makes sense to start from an assessment rather than picking products.

These are what we usually recommend people focus on:

• How long your perimeter is, and what your fence is made of
• Whether your yard is busy overnight with shunting and deliveries, or empty and locked.
• The value of the stock you hold, and how exposed it is.
• Whether there’s power where you need to set up monitoring systems.
• What your insurer asks you for.
• Your budget and whether you need cover now or for the long term.

We’d advise a site assessment before you buy any equipment so you understand where your weak points are, which will guide on what security systems will offer the best protection.

For the wider picture of keeping your warehouse secure, from the gatehouse to the goods-in door, it’s worth looking beyond the perimeter too.

Layered Perimeter Security For Warehouses With ProFM Group

It’s important to consider that detecting an intruder and stopping one are two different jobs.

But that doesn’t mean you need two providers.

There’s no point choosing a CCTV installation company if they can’t provide anyone to watch the cameras they install (and you don’t have the manpower).

Similarly, it doesn’t work to have someone watching your cameras without them being able to alert security personnel on the ground if they see something happening.

This is where our all-in-one solution works.

Our NOC monitors your CCTV round the clock and our self-contained VPODs can cover sites without power.

As an SIA Approved Contractor covering more than 400 intruder alarms for clients 24/7, we make sure the people answering your alarm are vetted and licensed.

You can read how this approach to perimeter security systems works in the real world in our case study with Lloyds Transport and Warehousing, where we provide 24/7 security.

If you’re reviewing your warehouse security, we’d be glad to talk it through and give you a free, no-obligation quote.

Call 0808 501 5332 or get in touch through our contact page.