Fire Resistant Glass FAQ
All your Fire Resistant Glass questions answered
Q1. Where must fire-resistant glass be used?
Fire-resistant glass is normally used to prevent fire spread and to provide a safe
escape route and safe access for fire-fighters. The national documents providing
guidance on how to meet Building Regulations (e.g. Approved Document B for
England and Wales) show where fire-resistant barriers are required. If an alternative approach has been taken to demonstrate compliance with Building Regulations, such as a fire safety engineering design study, then the applications for fire-resistant glass must be specified in the appropriate design report.
Q2. When must the glass be integrity-only and when must it have insulation performance?
The areas of application for integrity-only or integrity and insulation performance
are given in the appropriate guidance to the Regulations, or in the appropriate design report if the building is subject to a fire safety engineering study.
Q3. How can it be ensured that the specified system is appropriate for the application?
The specified glazed system must have appropriate evidence of performance based
on appropriate test information. This evidence may be provided either in a test
report, or in an assessment report or by third party certification. The test evidence that is provided must be appropriate to both the application and the specific glazed system that is to be installed.
Q4. Is it possible to obtain a fire certificate for installed fire-resistant glass products?
Fire certificates are provided by the Fire Service to approve certain premises and
are not applicable to individual products, systems, assemblies or installations.
Under new Regulations, fire certificates are to be phased out during 2006 and
replaced by making the Responsible Person, i.e. the building or business owner,
responsible for ensuring that appropriate fire precautions and safety measures are
in place. Product certificates may be referred to in the context of third-party
certification schemes, but these are voluntary and not obligatory. The appropriate
evidence of performance for a fire-resistant glazed system is normally a test or an
assessment report, which must be provided by the supplier on request.
Q5. Why can’t toughened glass be used for fire-resistant applications?
Standard toughened glass is not able to withstand the thermal shock generated
during a fire and it must not be used where fire-resistant barriers are required.
There are a number of specially modified toughened soda-lime glass types available for fire-resistant applications in very specific framing systems, or special glass
compositions such as toughened borosilicates that can be used, but both types are strictly subject to manufacturers’ specific guidance on their use.
Q6. Can it be assumed that a fire-resistant glass successfully tested in single glazing will give the same performance in an IGU?
Never make assumptions. In all cases appropriate proof of performance must be
available related to appropriate test evidence.
Q7. What is the biggest pane size that can be used?
The pane size will vary according to the glass and framing system, always subject to
the availability of appropriate test evidence. In every case, contact the glass
manufacturer or supplier for the maximum glass sizes tested and the associated framing system details.
Q8. What edge cover should I use when glazing fire-resistant glass?
Different glass types will require different amounts of edge cover according to their
individual requirements. Manufacturers/suppliers will provide appropriate guidance,
which must be followed. Modified toughened soda-lime glasses are particularly
sensitive to edge cover which is generally a maximum of 10mm cover. If the edge
cover is too great for this type of glass then premature failure is far more likely.
Q9. When glazing must I allow for expansion of the fire-resistant glass?
Normal glazing codes of practice must be followed. Glass in any application must
never be glazed tightly. Expansion allowances can be especially critical for modified toughened soda-lime glass types. The glass manufacturer/supplier will define
expansion allowance required.
Q10. Can PVB laminated glass be used for fire-resistant applications, as it is a safety glass?
PVB laminated safety glass does not have any fire-resistant properties and it must
not be used in fire-resistant applications. Safety glass types with fire-resistant properties are available, based upon special inter-layers.
Q11. Can the maximum pane size be increased beyond what was tested?
Only limited increases in tested pane sizes are allowed, according to assessment. The evidence provided by the glass manufacturer/supplier will provide the maximum pane size allowed for each particular system.
Q12. Can the pane height be increased while reducing the width, keeping the same area?
This is only possible if there is test evidence that the modified dimension meets the
fire-resistance performance. Details will be made available by the glass manufacturer/
Q13. What size and shape of glazing bead can be used?
This information can only be identified by reference to the approved glazing systems, and the size of bead will vary according to the glass and system chosen.
Q14. Can the tested gasket or seal be exchanged for an alternative?
This may be possible but only if the alternative has documented evidence showing that it can be used with the glass and framing system. If this evidence is not available, contact the gasket or seal supplier for confirmation of acceptability.
Q15. What glazing seals must be used?
The glazing seal has to be appropriate for the chosen system based on test evidence. Standard glazing seals must not be used for fire-resistant glazing.
Q16. How big a piece of glass can be installed into a timber fire door leaf?
This depends on the door leaf being used, as each door manufacturer will have tested different sizes of glass with their door leaf types. Maximum glass size can also depend on the glazing system being used in the door. The test or assessment information for the specific door leaf and glazed system will dictate the allowable maximum glass size and glass aspect ratio. It should be noted, that great care needs to be taken when cutting apertures into door leaves because this can adversely affect the fire-resistance performance of the door and this must only be done according to the door manufacturer’s guidance and instruction. Impact safety may also limit maximum glass size: if the glass has a class C impact safety rating then glazed door panels are limited to a maximum of 900mm.
Q17. What shapes of vision panel can be used in a timber door leaf?
Various shapes are possible but the types and sizes will depend upon the evidence available for the door leaf and the glazing system. If the evidence is unavailable for the required shape, then the shape must not be used. It should be noted that great care needs to be taken when cutting apertures into door leaves because this can adversely affect the fire-resistance performance of the door.
Q18. What happens if a different species of timber is used?
Different timbers have different burning characteristics and can influence the performance of the door or framing system. An alternative timber should not be used unless there is appropriate fire test evidence.
Q19. What is the minimum frame section that may be used in a timber glazed system?
The minimum section will be the size that can be demonstrated to work with the chosen fire-resistant glass. This can be identified by reference to fire test report. Contact the glass manufacturer/supplier for the appropriate information.
Q20. Can square timber beads be used for fire-resistant glazing?
Yes, in certain cases. For insulation glass types, in particular, square beads present few problems but integrity-only glass types require more detailed consideration as transferred heat can lead to bead ignition on the protected face. Partial insulation glass types may also allow the use of square beads, subject to appropriate evidence of performance based on tests.
Q21. Can fire-resistant glass be installed into metal frames?
Steel and aluminium framing systems may be used but only if the frame is specifically designed as part of an approved fire-resistant glazed system. Standard steel or aluminium framing systems are not suitable for fire-resistant applications.
Q22. Can fire-resistant glass be installed into frameless systems?
Yes, by using specialist glass and glazing systems that have the appropriate fire test evidence. Contact the glass manufacturer/supplier for the appropriate information.
Q23. Is it possible to have glass supplied for installers to fit within their own frames?
All glass types are available on a supply-only basis but it must always be fitted into a frame that has the appropriate test evidence, using the glazing seals and bead types that are approved for that particular glazed system. Competent persons who have the relevant specialist knowledge must always carry out the installation of the glazed system, according to the construction and components given in the accompanying evidence of performance. Fire-resistant glass must only be used as part of an appropriately approved glazed system.
Q24. The glass in an existing aperture must be replaced, can a suitable glass be supplied?
All fire resistant glass types may be used in refurbishment glazing but the glass and seals must be replaced on a like-for –like basis in the existing frame according to the original evidence of performance provided for the particular glazed as installed. When carrying out any replacement glazing, the frame must be checked to ensure that it is in a suitable condition for re-glazing to be carried out. In all cases, the replacement must be and approved fire-resistant glazed system with appropriate evidence of performance, and the performance rating of that system must be appropriate to the latest guidelines, for example as given in the latest version of Approved Document B (England and Wales). If there is any uncertainty about any of the components that have to be replaced, or uncertainty about the performance rating that is required, then expert guidance must be sought from a member of the GGF’s Fire Resistant Glazing Group.