By Cath McLean, Segment Manager for glass at Promat UK.
Fire resistant glazing plays a key role in creating buildings that give occupiers or users safe routes of escape in the event of an emergency, But as the spotlight falls on the fundamental question of how effective passive fire protection products actually are, it is vitally important that what we think we know is correct in terms of designing and installing fire resistant glazing.
Standard glass versus fire resistant glass
Fire resistant glass is made using various technologies including, a modified toughening process, intumescent interlayers and intumescent gels to provide tested levels of fire protection. Standard glass, on the other hand, is highly susceptible to heat and provides little protection in the event of a fire breaking out – perhaps as little a few minutes before it breaks and allows the fire, heat and smoke to spread.
Fire resistant glazing will typically provide protection for a period of 30, 60,90, 120 or 180 minutes. This figure will be displayed next to the following types of protection:
- Integrity only (E) – fire glass at its most basic, preventing the flames and hot gases from spreading, but not stopping the heat from penetrating the glass.
- Radiation control (EW) – a step-up from integrity glass, offering a barrier to flames and hot gases, plus some of the fire’s heat.
- Integrity and Insulation (EI) – the highest level of protection, providing heat insulation as well as a barrier to flames and hot gases. It will maintain the temperature on the unexposed side at 140 degrees Celsius for the stated period determined by testing.
So, if the glass is integrity only and provides 30 minutes of protection, it will be classified as E30. An integrity and insulation glass with 60 minutes of protection would be described as EI60.
Too much room for interpretation?
The variety of standards covering fire protection measures in buildings makes it difficult to know if the ultimate installed products will deliver as intended. At the top of the list is Approved Document B which helps to determine where fire protection measures should be incorporated into a building, and the level of protection required. Unfortunately, it is not specific enough to be more than a guide which leaves the fire safety requirements open to interpretation and puts the onus on the specifier to get it right.
When choosing a passive fire resistant glazing system, depending on the type proposed, its configuration and location within the building, you may need to accommodate any combination of the following:
- BS 476 Part 22:1987
- BS EN 1364-1:1999
- For doors: BS EN 1634-1:2014
- BS EN 12600:2002 – Class 1B1 and BS 6206:1981
- CE-marked
- BS 5234-2 1992 (partition loads)
- BS 6180 (barriers in and around buildings)
- EN 12758 (sound reduction/acoustic performance)
Herein lies one of the big issues. Whilst these standards, guidance and legislation are very well-intentioned it has become difficult for all parties in the supply chain to clearly assess if the installed systems will perform as intended in the event of a fire. This situation is exacerbated because there is no requirement for the competency of the installer.
Design and construct as specified
Fire resistant glass is one part of a tested construction, along with the framing materials. It is vital, therefore, that the materials used at the point of installation are exactly those specified and tested together. This is the only way to ensure compatibility for the required performance. Substitution of similar products could lead to the systems being compromised in the event of a fire.
This is why Promat UK provides a 360 degree wheel of assurance approach. This involves working with architects to design and specify systems to the appropriate requirement using tested systems within the Promat SYSTEMGLAS® range, which incorporates steel, timber and calcium silicate products. This ensures control of the supply chain, working with manufacturing partners and approved installers to ensure what is specified is what is delivered. A final inspection completes the wheel with a certificate issued to validate the system.
Aesthetics, light transmission and acoustics
With the right specification, glazed partitions enable designers to balance aesthetics, acoustics, energy efficiency and fire safety. Often there is a desire to increase the natural light levels in areas such as internal office spaces and atria. A butt jointed glazing system is ideal in these situations, and these are available with EI passive fire protection system plus acoustic insulation. Promat SYSTEMGLAS® is one such solution, with combinations of glass available to increase flexibility and incorporate tinted, coated and patterned glasses. Remember too that there are also options to include fire rated glass doors within these glazing systems to complete the package.
Acoustic challenges can also be addressed in combination with light transmission and fire safety. This can easily be achieved using a combination of acoustic and intumescent interlayers with the fire resistant glasses within a system.
