As Featured in PRO INSTALLER Magazine - 10/18
Phil Brown, European regulatory marketing manager at Pilkington United Kingdom Limited, part of the NSG Group, offers his top tips to help installers understand the key regulations when installing security glass.
Security glass means designers don’t have to compromise between protecting buildings and allowing them to be filled with natural light.
It is used in applications where either people or property needs to be protected, whether against manual attack, firearms or explosions.
Here are our top tips for installers working with this product type.
1. Every element matters
The security glazing products on the market today can provide an impressive level of resistance to attacks, whether these are carried out using hands and feet, a tool such as a brick or an axe, or even ballistics or explosives.
However, no matter how effective the glazing might be in standing up to these attacks, its effectiveness will be undermined if the framing and supports keeping it in place do not provide at least the same amount of resistance.
So, any method used to fix security glazing in place must have enough strength to stand up to the anticipated means of attack. This includes any doors or other means of access in which the glass might be installed. If suitably configured, the glass is designed to break but stay in place.
2. Lock in the edges
A 50mm-thick sheet of laminated glass that might be able to stand up to an attack with an axe won’t protect a building if an attacker is able to lever it out of its frame, so ensuring rebates are deep enough to prevent this is essential.
One of the major benefits of appropriately designed laminated glass is that the interlayers retain their integrity even if the glass is fractured, so any would-be intruder won’t be able to enter the building even if they attack the glass hard enough to break it.
Again, though, this benefit only holds true if all edges of the glazing are properly ‘locked’ in place inside the rebates. This can either be done by clamping pressure – usually only in the case of single glazing – or, more likely, by using an appropriate sealant.
Where the lower edge of the glass meets a counter top – as is the case in many applications from banks to convenience stores – the structure connecting the two elements must provide the same level of support as for the other edges of the glass. This includes areas around any apertures intended for transactions or communication.
3. Consider whether the glass is designed to fracture
When laminated security glazing is specified, there are two different approaches to providing the required level of resistance – glass that is designed to break in the event of an impact, while remaining in one piece, or glass that is strong enough to resist fracturing.
Sometimes a specifier will choose glass intended to crack because it offers a more affordable solution while still delivering a high level of access prevention.
Which approach the specifier has taken has an important impact on the framing that must be used to hold the glass in place. This is because a pane that is intended to break will exert less force on its framing than one that is designed to maintain its structural integrity.
For glass that is not intended to break, the fixing design will be significantly more heavy duty, especially if the glass is intended to provide resistance to explosive blasts. In such cases, the forces that will be transferred from the glass to the framing and the whole building structure must be considered by the building’s designer.
Where the glass is intended to fracture, the key is to use rebates that are deep enough to keep a broken pane of glass, held together by its interlayer(s), in place. Ideally, a tested framing system and proven fixing method should be used. In general, increased edge cover may be necessary compared with conventional glazing systems.
4. Get the right support
To ensure the installation will stand up to the specified level of attack, it is important that it is strongly anchored into the building.
Any vertical supports, or mullions, must be securely fixed at ceiling and floor levels, and generally they should be taken through any suspended ceilings and raised floors and fixed to structural elements of the building.
In the same way, horizontal supports, or transoms, should be securely fixed at each junction with the vertical supports and walls where appropriate.
5. Know your standards
Specifications for the security glass that should be used in any given application are laid out in a series of British Standard documents.
It’s worth referring to the relevant standard(s) whenever you set out on a security glazing installation, to ensure all elements comply and to instil confidence in your clients.
For example, in the case of resistance to manual attack the relevant standard for the glass is BS EN 356, for which classifications range from P1A (the lowest) to P8B (the highest). There are equivalent standards for windows and doors, for example BS EN 1627 for burglar resistance. Other standards are available covering ballistics and blast resistance.
The standards are available on the BSI website, www.bsigroup.com.