Iain McIlwee explores some of the seemingly small details to consider when it comes to fire door glazing, and why they make such a big difference in the event of a fire
WHILE CONCERNING, the announcement in March from detectives investigating the Grenfell Tower tragedy that a fire door – which was taken from the building and was supposed to resist fire for 30 minutes – was in fact only able to withstand fire for 15 minutes in tests, is sadly not a surprise. Professionals who work in fire and risk management will understand that fire doors play a critical role in protecting occupants, buildings and firefighters.
However, despite the shocking headlines, too many people do not give fire doors a second thought – they forget that the real job of a fire door is to provide a barrier to fire, prevent it from spreading throughout a building, and keep escape and access routes clear. The fire door is about more than just the door – it’s a system of components that must all work together to ensure that the door will perform when needed.
Think of fire doorsets and assemblies as complete product systems – the door leaf, the frame, the ironmongery, the seals and any glazing system or component must work hand in hand to ensure that a fire door will perform when needed. A glazed aperture in a fire door, and fire resistant glazed screens that may surround it, all play an integral role in providing safety and light in everyday use. In the event of a fire, these elements will need to resist it for the specified amount of time, as well as give crucial visibility of escape routes and to the extent of the fire that is being withheld.
Firstly, ensure that your existing or new fire doors are manufactured by a company that holds third party certification for the specific product in question (including any glazing system). The reassurance that this provides is that the manufacturer is audited by an independent third party, which not only checks that a product is tested appropriately, but also that the product is retested on a regular basis. It also checks that the factory production control system (the manufacturing operation) is externally audited, to ensure that the product is manufactured consistently to a tight specification within the limitations of the scope set through the certification process.
Manufacturers are required to undertake regular training, and to make available critical information to support subsequent operations such as glazing, checking compatibility of components and maintaining the scope of certification. How apertures are prepared and doors are glazed is a critical part of certification – for example, when installing fire resistant glazing systems or other components such as letterplates, air transfer grilles and some door furniture.
The other benefit that you have with doors that are manufactured within third party certification is that they should also carry traceability of the product. You can find out if an existing fire door is manufactured by a member of BWF-Certifire by checking the top edge for the ‘badge’ or label/s. These labels identify the manufacturer, the relevant fire door certificate that holds all of the detail related to the specification of the product, and a unique traceability number referring back to production records within the manufacturing facility, and to that specific door.
This means that the original fire certificate and the original specification can be sourced and used to carry out checks on the product which is installed on site, to ensure compliance and that the correct specification is maintained if any components need to be replaced during the lifetime of the door. It can also be used to check whether the door is the correct application or configuration according to the door’s fire test evidence and certificate.
There are various third party certification schemes operating in the UK, but it is estimated that over 75%1 of the certified timber fire doors and doorsets sold in the UK are manufactured by members of the BWF-Certifire Fire Door and Doorset Scheme. Other certification schemes have different labels or plugs that identify the manufacturer and the specification of the product.
Small details, big difference
If you are specifying, fitting, checking or maintaining fire doors and fire resistant glazed screens, it is important to remember that the small details make all the difference and can severely impact performance of the overall fire door. Performance of a glazed aperture is not just about the specification of the glass, it also relates to the preparation of the aperture and the compatibility of the entire system of components (the glazing system).
The specification of all the other elements of this system (such as the bead design and material, bead fixing system, intumescent protection and even the overall size of the aperture that is cut into the doorleaf) impact upon performance. Tolerances are extremely tight, and the level of workmanship needs to be high to ensure performance. There are also strict rules about the compatibility of different glass types and their relevant glazing systems, their location within the doorleaf, and the overall area of glazing in the doorleaf.
It is vital that specialist fire glass is used which will perform effectively in the event of a fire. There are three different classifications of fire resistant glass:
- Integrity only (classification E) glass stops the passage of fire and smoke, but does not stop any radiant heat.
- Radiation (EW) glass also stops the passage of fire and smoke, but in addition offers some reduction in heat transfer to the non fire side of the door.
- Finally, integrity and insulation (EI) glass works in the same way as integrity, but offers significant reduction in heat transfer to the non fire side.
Within these classifications, there are many different products that perform in slightly different ways, and for different periods of time (30 minutes, 60 minutes and so forth), so the specification of specific glass type and classification is a really important decision. Just think about the amount of paperwork that is piled up in an average office – in the event of a fire, heat radiation alone can ignite paper, cloth and other materials at an alarming speed.
Beyond the type of glass used, there is a host of details that make a huge difference when it comes to fire door glazing systems, either because they would invalidate the certification of the door, or because in the event of a fire, they would weaken the performance of the door itself. It is absolutely vital that the correct and compatible system of components is used within the glazing system.
Compatible means that only the correct suite of components – including the bead, fixings and any correct intumescent protection – has been used within the design, in accordance with the third party certification that exists for the specific door in question. Compatible also means that the other limitations of relevant certification, such as the overall size of the aperture cut into the door leaf, the area of the glazed aperture and the location of the glazed aperture within the doorleaf, have also been complied with.
Within the BWF-Certifire scheme, because of the complex system of components required for fire resistant glazing systems and the high level of workmanship required, to maintain third party certification fire doors must be glazed by a trained technician who has been licensed to do that work, and work must be carried out in a factory environment. Any glazing of doors or cutting of apertures for glazing on site is prohibited, and again would mean that certification is broken and there is no guarantee of performance.
If a BWF-Certifire licensed processor fits a vision panel in a fire door, it will attach its own label next to that of the original BWF-Certifire fire door manufacturer, and the traceability of where that glazing took place is maintained. If the glazing was undertaken by the original BWF-Certifire manufacturer, then this scope is recorded in its label trail. If the door has had a fire resistant glazing system fitted by an unlicensed processor, or on site, and does not maintain this label traceability, the door certification is invalidated.
Remember that fire resistant glazing systems are complex systems of components, and that each detail must be correct in order to ensure performance and maintain third party certification. If you require information, you should refer back to the manufacturer and the scope of its certification.
The above guidance applies to FD30 fire doors – those doors designed to withhold a fire for 30 minutes. The use of glazing in FD60 fire doors (designed to last for 60 minutes) is a separate matter, and can be still more complex. Guidance can be found at www.bwfcertifire.org.uk/fire-door-procurement-tool
Fire Door Safety Week
Accuracy of fire door specification is so important because they don’t only protect occupants from fire, but can also act to delay the spread of cold smoke around a building, keeping escape routes clear.
The danger of cold smoke in a fire is the focus of the Fire Door Safety Week 2018 campaign run by the British Woodworking Federation, which takes place during the week starting 24 September.
The British Woodworking Federation has been running the Fire Door Safety Week campaign for seven years to raise awareness of the important role that fire doors play in protecting occupants and those who respond in emergencies, as well as in reducing property damage. Fire related injuries, such as burns, are not the main cause of death in fire related fatalities. In fact, the leading cause of death in fires2
is smoke inhalation.
This year, we will be sharing resources and information for fire and risk professionals, as well as the wider construction industry, concerning the dangers of smoke and the importance of fire doors as a barrier to smoke spreading.
Supporters of our campaign will be getting the word out in the media and online, but for further information about how you can get involved, please visit www.firedoorsafetyweek.co.uk
Five step door check
- Certification – look for a label or plug on top (or occasionally on the side) of the door. You can use the selfie function on your camera phone or a mirror to check. If there is one, that’s good news, otherwise report it to whoever is in charge of your building.
- Gaps – check that the gaps around the top and sides of the door are consistently less than 4mm when closed. You can use a £1 coin to give a feel for scale, this is about 3mm thick. The gap under the door can be slightly larger (up to 8mm is not uncommon), but it does depend on the door. As a rule of thumb, if you can see light under the door, the gap is likely to be too big – if the gaps are too big, smoke and fire could travel through the cracks.
- Seals – look for any intumescent seals around the door or frame. Check they are intact with no sign of damage. These seals are usually vital to the fire door’s performance, expanding if in contact with heat to ensure fire (and in some cases, smoke) can’t move through the cracks.
- Hinges – check all hinges are firmly fixed (three or more of them), with no missing or broken screws. Open the door and take a look at the hinges. Be sure the door is properly maintained and will perform properly in the intensity of a fire.
- Closing properly – check the door closes firmly onto the latch without sticking on the floor or the frame. Open the door about halfway, let go and allow it to close by itself. A fire door only works when it’s closed. A fire door is completely useless if it’s wedged open or can’t close fully.
Iain McIlwee is chief executive officer of the British Woodworking Federation. For more information, view page 5
- the key facts about fire door glazing are explained on this fact card from BWF-CERTIFIRE: www.bwfcertifire.org.uk/assets/bw639-glazing-fc-2.pdf
- The Fire Door Best Practice Guide: www.bwfcertifire.org.uk/assets/bwf-best-practice-guide-2016.pdf
- different glass types are explained here: www.bwfcertifire.org.uk/assets/bwf-best-practice-guide-2016.pdf
- a register of approved fire door installers is available here: www.firedoorinstaller.co.uk/
- more information on best practice in fire glazing can be found at the Glass and Glazing Federation website: www.ggf.org.uk/group/fire-resistant-glazing-group
- this film, produced last year for Fire Door Safety Week, shows the impact of getting the small details right regarding fire door glazing: www.firedoorsafetyweek.co.uk/video-specification-installation/