GRP Standards: Palisade, Mesh and Frangible
More Than Just a Fence
Fencing, at its most basic, defines a boundary and deters unauthorised access. But in the sectors where GRP fencing is specified — railways, electrical substations, airports, water treatment works, defence installations, and chemical plants — a fence must do significantly more than keep people out. It must be electrically non-conductive. It must not corrode. It must not interfere with radar or navigation systems. In some applications, it must break away on impact without harming an aircraft. And in all applications, it must demonstrably meet the relevant British Standard.
GRP fencing addresses every one of these requirements. It is the only fencing material that is simultaneously strong, corrosion-proof, electrically non-conductive, electromagnetically transparent, non-magnetic, and lightweight. No steel fence, no aluminium fence, and no timber fence can make all of those claims.
But here is the critical point for this article: not all GRP fencing is tested. Not all GRP fencing complies with BS 1722-12. Not all GRP fencing has been independently verified. Engineered Composites’ GRP palisade fencing system is the only system in the UK that has been independently laboratory tested and certified to BS 1722-12:2016, including full pull-out testing. That is not a marketing claim — it is a verifiable fact, and it matters.
1. Three Types of GRP Fencing: Know What You Are Buying
GRP fencing is not a single product. There are three distinct types, each designed for different applications and governed by different standards.| Type | Construction | Primary Applications |
| Palisade | Vertical pales (W or D profile) passing through horizontal rails, mounted on posts at 2.75m centres. Heights 1.2m to 3.0m. | Substations, railways, water treatment, industrial sites, MOD, general perimeter security |
| Mesh | Welded or woven GRP mesh panels mounted in GRP frames on posts. Dense mesh options available for small animal exclusion. | Airports, radar installations, substations requiring visibility, animal exclusion requirements |
| Frangible | Designed to fail safely under specified impact loads. Frangible posts or breakaway connections allow the fence to collapse without creating secondary hazards. | Airports — within ICAO frangibility zones (60m of runway/taxiway centrelines) |
CHOOSING THE RIGHT TYPE
Palisade provides the highest physical security and is the standard choice for perimeter protection. Mesh provides visibility and radar transparency whilst maintaining security. Frangible is a specialist product for airports where ICAO Annex 14 requires structures to break away under aircraft impact. If you need a general-purpose security fence for a substation, railway, or industrial site, palisade is almost certainly the correct choice.
2. The Standard: BS 1722-12:2016
BS 1722-12:2016 is the British Standard for steel palisade fencing. There is, at present, no dedicated British Standard for GRP palisade fencing. This creates a question that buyers rightly ask: if the standard is written for steel, what does GRP compliance with it actually mean?
The answer is that BS 1722-12:2016 defines the performance requirements — dimensions, pale spacing, post centres, structural integrity, and resistance to removal — that any palisade fence must meet regardless of material. A GRP palisade system that has been independently tested and certified to BS 1722-12:2016 has been proven to deliver the same structural and security performance as a steel system that meets the same standard.
2.1 What BS 1722-12:2016 Covers
- Fence classifications: General Purpose (standard security) and Security (enhanced).
- Heights: Standard heights from 1.0m to 3.0m.
- Post centres: 2.75m maximum for standard panels.
- Pale profiles: W-section and D-section pale options with specified top configurations (triple point, single point, round and notch).
- Pull-out resistance: The critical test. Pales must resist a specified force before they can be removed from the horizontal rails. This is the primary security metric.
- Gate specifications: Single and double gates with standard widths and locking requirements.
2.2 The Pull-Out Test: Why It Matters
The pull-out test is the single most important test for palisade fencing security. It measures how much force is required to remove a pale from the horizontal rails. If a pale can be pulled out easily, an intruder can create a gap in the fence wide enough to pass through. The entire security function of palisade fencing depends on pull-out resistance.
Our GRP palisade system has been independently tested and complies with the pull-out test requirements of BS 1722-12:2016. This means that our pales resist removal with the same effectiveness as steel pales tested to the same standard. No other UK GRP palisade manufacturer has this independent laboratory verification.
3. Why GRP Fencing: The Properties That Steel Cannot Match
| Property | GRP Palisade | Steel Palisade |
| Electrical conductivity | Non-conductive — inherent insulator. Eliminates touch voltage and step potential risks entirely. | Highly conductive — requires earthing. Can transfer fault voltages across entire perimeter. |
| Corrosion | Immune — does not corrode in any environment | Corrodes — requires galvanising and/or painting. Coastal and chemical environments accelerate failure. |
| Electromagnetic transparency | Fully transparent — does not reflect radar, does not interfere with navigation aids, does not cause ILS beam bending | Reflects radar signals. Creates false returns. Causes ILS interference. Must be charted as obstacle. |
| Magnetic properties | Non-magnetic — no compass deviation, no interference with sensitive detection equipment | Ferromagnetic — affects compass navigation, interferes with detection equipment |
| Weight | Less than 40kg per panel — manual handling by two people, no crane required | 80–100kg per panel — mechanical handling required on most sites |
| Scrap value | Zero — no incentive for theft | High scrap metal value — frequent theft target on railways and utilities |
| Maintenance | None — no painting, no anti-corrosion treatment, ever | Regular repainting required. Galvanising has finite life. |
| Design life | 30+ years, no degradation | 15–25 years before corrosion affects integrity (less in aggressive environments) |
4. Sector by Sector: Where GRP Fencing Is the Only Sensible Choice
4.1 Electrical Substations
This is the application where GRP fencing delivers its most compelling safety advantage.
When an electrical fault occurs at a substation, Earth Potential Rise (EPR) can transfer dangerous voltages across any conductive material connected to the earth grid — including steel fencing. A person touching a steel fence during an EPR event can receive a lethal electric shock. This is not a theoretical risk; it has caused fatalities.
GRP fencing eliminates this risk completely. It is electrically non-conductive. It cannot transfer fault voltages. There is no touch voltage hazard and no step potential risk. It does not need earthing because there is nothing to earth.
For Distribution Network Operators (DNOs) specifying perimeter fencing for 11kV, 33kV, 66kV, and 132kV substations, GRP palisade fencing is the only material that eliminates the EPR touch voltage hazard by design.
4.2 Railways
The UK railway network operates at 750V DC (third rail) and 25kV AC (overhead line electrification). Steel fencing within the railway environment creates two specific risks: electrical conduction if the fence comes into contact with the electrification system, and theft of the fencing itself for scrap metal value.
GRP fencing eliminates both risks. It is non-conductive, so inadvertent contact with the electrification system does not create a hazard. And it has zero scrap metal value, so there is no incentive for theft. Our GRP palisade fencing is widely installed across the Network Rail estate and is trusted by rail contractors and TOCs throughout the UK.
4.3 Airports
Airports present unique fencing challenges that no other material can address as effectively as GRP:
- Radar transparency: GRP is fully transparent to radio frequency signals across all aviation bands. Steel fencing reflects radar signals, creating false returns and clutter on Airport Surveillance Radar (ASR) screens. Steel near Instrument Landing System (ILS) installations causes beam bending and course deviation, which is a direct flight safety hazard.
- Navigation aid protection: VHF Omnidirectional Range (VOR) and Distance Measuring Equipment (DME) sites require non-metallic, non-magnetic perimeter protection. GRP is invisible to these systems.
- ICAO Annex 14 frangibility: Within 60 metres of runway and taxiway centrelines, ICAO requires that obstacles must break away under aircraft impact without causing secondary damage. Our GRP frangible fencing system is specifically designed to meet this requirement, failing safely under impact loads exceeding 55kJ.
GRP fencing is installed at over 100 airports worldwide, including major international hubs.
4.4 Water and Wastewater Treatment
Water treatment facilities present aggressive corrosion environments: constant moisture, hydrogen sulphide (H₂S) gas from sewage processes, chlorine dosing chemicals, and in coastal locations, salt-laden air. Steel fencing in these environments requires frequent maintenance and has a significantly reduced life. GRP fencing is immune to all of these corrosion mechanisms and will maintain its structural integrity and appearance for the full design life of the installation with zero maintenance.
4.5 Defence and Military
Military installations housing radar, communications, and electronic warfare equipment require perimeter fencing that is electromagnetically transparent, non-magnetic, and does not create a detectable thermal signature. GRP palisade fencing meets all of these requirements. It cannot be detected by metal detectors from outside the perimeter, and it does not interfere with sensitive detection, surveillance, or communications equipment within the installation.
4.6 Chemical and Industrial
Chemical plants, fertiliser works, offshore installations, and heavy industrial sites expose fencing to acids, alkalis, solvents, and aggressive atmospheres. Steel fencing life in these environments can be as low as 5–10 years. GRP fencing is chemically inert and will outlast steel by a factor of three to ten in aggressive chemical environments.
5. Product Specifications: What You Should Be Receiving
| Parameter | Specification |
| Standard heights | 1.2m, 1.5m, 1.8m, 2.4m, and 3.0m. Custom heights to 3.6m available. |
| Post centres | 2.75m standard, matching BS 1722-12:2016 requirements |
| Pale type | W-profile and D-profile pales, 65–75mm wide, with triple point, single point, or round and notch tops |
| Panel weight | Less than 40kg per assembled panel (vs 80–100kg for equivalent steel) |
| Post type | Embedded (concrete or driven) or surface-mounted (base plate with stainless steel fixings) |
| Material | Pultruded GRP: E-glass fibre reinforcement, isophthalic polyester resin, fire retardant |
| EN 13706 grade | E17 or E23 depending on application |
| Fire performance | BS 476 Part 7 Class 1 and Class 2 available. EN 13501-1 classification B-s1, d0 on profiles. |
| Operating temperature | -40°C to +120°C |
| UV resistance | UV stabilised resin with polyester surface veil on all external surfaces |
| Colours | Grey (RAL 7001) and Yellow (RAL 1004) as standard. Bespoke colours on project quantities. |
| Gates | Single gates: 900mm and 1200mm wide. Double gates: 4000mm and 6000mm wide. Heights to match fence. Surface or embedded mounting. |
| Supply format | Pre-drilled kit form — all components supplied ready for assembly, reducing installation time by up to 50% vs steel |
6. The Testing Question: Independently Verified or Marketing Claims?
This is the section that differentiates a credible GRP fencing supplier from one that is not.
There are GRP fencing products available in the UK market that carry no independent test certification whatsoever. They may state ‘designed to BS 1722-12’ or ‘compliant with BS 1722-12’, but without an independent laboratory test report, these are statements of intent, not evidence of compliance.
The difference matters. BS 1722-12:2016 specifies pull-out test requirements. The only way to verify pull-out resistance is to test it. Pales must resist a defined force before they can be removed from the horizontal rails. Without that test, you are installing a fence whose security performance is assumed, not proven.
Engineered Composites’ GRP palisade system has been independently laboratory tested and certified to BS 1722-12:2016, including full pull-out testing. We are the only UK GRP palisade manufacturer that can provide this independent verification. We have been supplying this product for over 20 years to Network Rail, power utilities, water companies, and Ministry of Defence sites across the UK.
WHAT TO ASK EVERY SUPPLIER
Can you provide an independent laboratory test report confirming compliance with BS 1722-12:2016, including pull-out test results? If the answer is no, you are buying an untested product. The fence may look identical. The difference is that one has been proven to resist forced entry, and the other has not.
7. The Cost Conversation: Think About the Problem You Are Solving
7.1 Why Is GRP Being Specified?
GRP fencing is not specified as a like-for-like replacement for steel. It is specified because steel cannot be used. If the site is an electrical substation, steel fencing creates a touch voltage hazard. If the site is near a radar installation, steel creates signal interference. If the environment is chemically aggressive, steel will corrode and require replacement.
In these applications, the relevant comparison is not ‘GRP vs steel’ but ‘GRP vs the cost of managing the problems that steel creates.’
7.2 Installation Savings
GRP panels weigh less than half of steel equivalents. They can be handled manually without mechanical lifting equipment. They arrive pre-drilled in kit form. Installation is typically 50% faster than steel. On sites with restricted access — railway trackside, rooftops, confined substations, remote locations — the handling advantage translates directly into reduced labour cost and shorter possession times.
7.3 Lifetime Cost
Steel fencing requires repainting every 7–15 years depending on environment. Galvanising has a finite life. In aggressive environments, steel fencing may need full replacement within 15–25 years. GRP fencing requires no maintenance and no replacement for 30+ years. Over a 30-year period, the total cost of ownership for GRP is typically lower than steel in any environment where corrosion or repainting is a factor.
8. Installation: Lightweight, Fast, and No Hot Works
GRP fencing installation has significant practical advantages over steel:
- No hot works: GRP components are connected with stainless steel bolts, not welding. No hot work permits required. Critical advantage on live railway possessions, substations, and chemical plants.
- Manual handling: Panels under 40kg can be carried by two people. No crane, no MEWP, no mechanical lifting on most installations.
- Pre-drilled kit form: All holes pre-drilled, all components supplied to length. Assembly is straightforward with basic hand tools.
- Cutting on site: If required, GRP can be cut with a diamond blade or fine-tooth saw. No oxy-acetylene, no hot sparks.
- Foundation options: Embedded posts (concrete or driven) or surface-mounted base plates with stainless steel anchor bolts. Surface mounting eliminates excavation on existing hardstanding.
- Slope accommodation: Panels can be raked (angled) to follow ground slopes without bespoke manufacturing.
9. The Buyer’s Checklist: 12 Questions for GRP Fencing
| # | Question | Good Answer | Red Flag |
| 1 | Has the system been independently tested to BS 1722-12:2016? | Yes — lab test report available | ‘Designed to’ or ‘meets’ |
| 2 | Can you provide the pull-out test report? | Independent lab report provided | ‘Not tested’ or ‘not required’ |
| 3 | How long has this product been in the UK market? | 10+ years with references | ‘New to market’ |
| 4 | Can you provide references from Network Rail, DNOs, or MOD sites? | Named projects and contacts | ‘Confidential’ |
| 5 | What is the declared design life? | 30+ years with supporting data | ‘Long lasting’ |
| 6 | What resin system — isophthalic polyester or other? | Isophthalic polyester, fire retardant | Unspecified or orthophthalic |
| 7 | What fire classification — BS 476 and/or EN 13501-1? | Both stated with test data | ‘Fire retardant’ only |
| 8 | Are gate systems tested and included in the BS 1722-12 certification? | Yes — gates included | Gates from different supplier |
| 9 | Is the product genuinely non-conductive including all fixings? | Stainless fixings, GRP structure | Galvanised or mild steel fixings |
| 10 | Is surface mounting available (base plate option)? | Yes — with SS anchor bolts | Embedded posts only |
| 11 | Are components supplied pre-drilled in kit form? | Yes — ready for assembly | Site drilling required |
| 12 | Can you provide an electrical resistivity certificate? | Surface/volume resistivity data | ‘It’s non-conductive’ |
10. The Bottom Line
GRP fencing is a specialist product for specialist applications. It is not the cheapest perimeter fence you can buy, and it is not intended to be. It is the only perimeter fence that is simultaneously non-conductive, corrosion-proof, electromagnetically transparent, non-magnetic, lightweight, and independently tested to BS 1722-12:2016.
In electrical substations, it eliminates touch voltage hazards that steel creates. On railways, it removes the theft incentive and the electrical safety risk. At airports, it protects radar and navigation systems from interference. In water treatment, chemical plants, and aggressive environments, it outlasts steel by a factor of three to ten.
And critically, our system is the only GRP palisade fencing in the UK that has been independently laboratory tested and certified to the British Standard. Over 20 years of installations across Network Rail, power utilities, water companies, and MOD sites confirm its performance in the field.
