General Purpose to Extra High Security Fence – Welded Wire/Expanded Metal
The secure level of mesh fence:
According to the secure level, open mesh steel panel fences (welded wire fence and expanded metal fence) are divided into four categories:
- General purpose fences up to 2400 mm high. The general purpose fence is intended for use as a boundary marker or for those locations where it is deemed necessary merely to deter the casual intruder or trespasser. For example, roll top fencing.
- Security fences at least 2400 mm high. The security fence is designed for use in areas where greater protection is required from vandalism or trespass, and can be considered suitable for use for general industrial security such as for industrial estates, airfields and oil installations. For example, clear view fence, expanded metal security fences.
- High security fences at least 3000 mm high. The high security fence is designed for areas where protection against determined intrusion is required. However, it should be appreciated that it is not possible to install a fence that cannot be negotiated by a determined intruder given adequate time, freedom from observation and suitable climbing aids or tools for forcing an entry. For example, 3D security fence.
- Extra high security fences at least 3000 mm high. The extra high security fence does not permit finger holds and therefore cannot be scaled without climbing aids. For example, anti climb fence, 358 mesh fence, 3510 mesh fencing.
Choosing a fence is affected by factors such as the intended purpose, desired service life, aesthetic consideration and availability of components.
|Fence category||Fence height
(excluding topping) (mm)
|Typical expanded metal specifications|
|BS 405 reference||LWM (mm)||SWM (mm)||Strand||Mass||Solidity
|General purpose fences||Max. 2400||Special||76||64||2.00||2.00||0.96||1.056||12|
|Security fences||Min. 2400||Special||76||64||3.00||3.00||2.21||2.431||14|
|High security fences||Min. 3000||EX44||100||50||3.00||5.03||4.66||5.126||20|
|Extra high security fences||Min. 3000||Special: aperture finger grip proof||70||10||3.00||5.50 Main strand||9.00||9.90||38|
|Fence Category||Fence height
|Typical welded mesh specifications|
|Vertical mesh spacing
|Horizontal mesh spacing
|Vertical wire diameter
|Horizontal wire diameter
|General purpose boundary fence||Max. 2400||200||50||5||7||14|
|200||50||6||double 8 mm horizontal wire||16|
|12.5 & 50||12.5 & 50||3||3||20|
|Security fence||Min. 2400||75||75||3||3||16|
|High security fence||Min. 3000||50||50||4||4||16|
|Extra high Security fence||Min. 3000
(Aperture finger grip proof)
OSF-01: Example of typical expanded mesh, see Table 1 above for characteristics of expanded metal for panel fences.
OSF-02: Examples of typical welded mesh for general purpose fences, security fences.
OSF-03: Examples of typical welded mesh for high security fences, extra high security fences.
- Post section moment of inertia
- at least 5.4 cm4 for fences up to 1800 mm high.
- 12.5 cm4 for fences over 1800 mm high.
- Post wall thickness:
- At least 2.5 mm for general purpose fences.
- 3.5 mm for high and maximum security Fences.
- Posts space not more than 3000 mm.
|Depth in ground
|Hole size (min.)|
Fence topping: barbed wire, barbed tape, razor concertina wire, and rotating deterrents.
- Barbed wire lines not less than three.
- The lowest line shall be not more than 150 mm from the top of the fence panel and the other lines shall be spaced at not more than 200 mm below the top of the extension arm.
Security against burrowing
If burrowing is a risk, one of the following measures shall be used:
- A concrete sill shall be provided.
- The panels shall be extended by 150 mm and embedded in the concrete sill.
- The panels shall be extended by 300 mm and buried in the ground.
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