In conjunction with the Glass and Glazing Federation (GGF), we examine some of the key aspects of fire-resistant glazing.
But fire-resistant glass can only achieve its designed performance when it is part of a complete fire-resistant glazed system. This means that all component parts – such as the glazing seal, beads, fixings and frame material – must be compatible and work together to achieve the required performance, and must be referenced to appropriate and relevant test evidence.
It’s also vital that the fire-resistant glazed system is installed as tested or assessed by a competent authority. The glass must be tested and classified in its proposed end use application, for example as a screen, door, roof, floor or façade in a glazed system appropriate for that application.
Installation must be carried out by competent individuals who can demonstrate the necessary knowledge and skills required through competent person or third party certification schemes.
Types of fire-resistant glazing
Fire-resistant glazing can comprise various types of technology. These include:
- Wired: In a fire, the glass fractures but the wire mesh holds the glass together to maintain integrity.
- Ceramic: The glass has a near-zero thermal expansion coefficient and a very high softening point, which maintains integrity.
- Heat Soaked Modified Thermally Toughened Soda Lime Silicate Safety: The toughening process develops high stresses which retain the integrity of the glass.
- Resin Laminated: Integrity is achieved with a resin-based interlayer which resists fire and flaming.
- Modified Toughened Laminated: The toughening process produces high stresses which retain the integrity of the glass.
- Thermally Toughened Borosilicate Safety: This type of glass remains intact due to its composition and low thermal expansion.
- Laminated Intumescent: These have an intumescent interlayer or interlayers which turn opaque and swell on exposure to fire.
- Gel Laminated: These also have an intumescent interlayer(s) which are formulated to turn opaque and swell on exposure to fire.
Fire-resistant insulating glass units
Insulating glass units do not provide fire-resistance unless they incorporate one of the types of fire-resistant glass shown in the table above, and have been fire performance tested. It’s important to note that:
- The insulting glass unit must have its own fire test or assessment report based on test evidence
- Fire-resistant insulating glass units must be CE marked (or national equivalent) in accordance with EN1279-5
- In some cases, it must be possible to confirm the direction of use before installation
- The components used in the insulating glass unit must be proven by test or assessment; the fire-resistant glazing system must be appropriate for the application of the integrated glass unit.
In all cases, the manufacturer or supplier must be consulted for evidence in support of the fire-resistant glazed system. Special glass units containing integral Venetian blinds may also be available as fire rated.
Horizontal and inclined glazing systems
Most fire-resistant glazed systems are installed vertically, but there are some specialist approvals for sloped and horizontal orientations.
Decorative treatments
Some types of glass can be decorated with surface treatments such as sandblasting and screen printing without reducing their fire resisting performance, but others cannot be. In all cases, the advice of the manufacturer or supplier must be obtained to ensure the treatment is appropriate and that evidence of performance is available.
Combined performance requirements
Other performance characteristics – such as thermal insulation, safety and security or privacy – can be combined with fire-resistant glazing without compromising its performance. Impact safety and manifestation (to minimise the risk of people accidentally walking into a glass partition) can be important additional requirements.
Classifications of fire resistance for UK Building Regulations
Integrity: Integrity glass has the ability to withstand exposure to fire on one side while preventing flames and hot gasses from penetrating through to the unexposed side. Alternatively, integrity may be referred to as non-insulating.
Insulation: In addition to the characteristics of integrity, insulation also limits heat transfer due to conduction, convection or radiation from the exposed to the unexposed face.
Approved Document B defines performance in terms of integrity only, or integrity and insulation, for a standard test time period and provides guidance according to the type of building, the application (e.g. walls, doors, floors) and the location of the glazing.
Specifying fire-resistant glass and glazing on-site
As well as paying attention to the correct design and specification of fire-resistant glazing systems, it is vital to check that everything is on order once on-site. This includes:
- Official evidence from a competent authority demonstrating the fire-resistant performance of the glazing system used
- Evidence of installer competence (e.g. from a UKAS-accredited certification body or competent person scheme)
- A permanent stamp on the glass that indicates, as a minimum, the name of the glass product and the manufacturer/supplier and ideally the fire performance rating (the stamp must be visible and readable after glazing)
- Marking of the impact performance class (i.e. class 1, 2 or 3 according to BS 6262 part 4 and EN 12600) where applicable
- Appropriate and proper storage of glass types and availability of appropriate handling equipment
- Full understanding and appreciation of health and safety aspects by those handling and installing fire-resistant glazing systems
A quick reference guide to the key factors to be considered in specifying fire-resistant glazing and appointing a glazing contractor
The GGF – with its new training partner Total Support Training – is working on producing fire-resistant glazing installation training courses.
This article is based on extracts from A Guide to Best Practice in the Specification and Use of Fire-resistant Glazed Systems by the Glass and Glazing Federation (GGF). Produced by the GGF Fire-resistant Glazing Group (specialist companies and professional experts), the Guide covers how fire-resistant glazing systems are used to control and contain the spread of fire and smoke, which allows enough time for a safe escape as well as safe access for fire services. This fourth revision tracks recent changes in legislation and incorporates updates in line with constant product development undertaken by the construction industry.